2013 Avoiding Defects Book

Avoiding Defects

REVISION D - July 2013

To be the most respected business in the industry requires us to deliver on every promise we make to our customers. This includes the delivery of a quality product that is free from defects.

The variety of work we undertake presents a number of technical and personal challenges to the achievement of this objective, especially given the high quality and often high value developments we are delivering across the whole of the UK and overseas locations within which we operate.

To help the business in the successful achievement of this critical task – to deliver at practical completion with zero defects – we have broadened the scope of the Target Zero Defects booklet, and now incorporates input from the Infrastructure as well as the Building elements of the business. This is the first publication of the booklet since this integrated approach, and demonstrates how we can easily and quickly achieve consistency across the whole of our Construction Division.

I hope you find the document of benefit: use it alongside our business management system, contract documents and specifications to ensure we design, procure and deliver to our contracted customer requirements.

And finally, I urge you to get involved. If you have new lessons learned, feed them into your BMS Managers or Business Improvement Managers to drive continuous improvement and ensure we delight our customers.

Steve Bowcott Chief Operating Officer Kier Group

Purpose The purpose of the Avoiding Defects booklet is to provide an easy to read aide memoire for use in the review of design, scoping of work packages, production of orders and the management of construction activities.

Its principle aim is to assist in ensuring work is built “right first time”, that the required quality is achieved and that our projects are handed to our clients with zero defects.

The booklet captures lessons learnt and key points gained from years of experience, over a wide variety of construction projects.

It has been contributed to by Kier personnel as well as subcontractors and supply partners.

Scope The Avoiding Defects booklet is to be used by all trading divisions with the Construction Division of Kier and covers the key work activities undertaken.

The booklet has two parts; the first part explains the approach to be taken and the second part contains helpful hints grouped by package.

Pocket sized hard copies have been produced for ease of reference on sites. An electronic version is also available to all staff.

Suggestions for improvement or addition can be made by via one of the contacts at the back of the booklet.

Key Generic Lessons: • Fire risk assessment for build methodology • Understand and comply with life cycle requirements

Updates & revisions This Avoiding Defects Booklet will be reviewed periodically in line with technical developments and lessons learnt. An electronic copy can be found on KIERdoc (MyKier).

Avoiding Defects - Revision D – July 2013

Revision D incorporates contributions from : Julian Barnett Matt Billiard Robert Blackwell Matt Bott Alan Burgess Robert Cameron James Carpenter Jason Chong Dion Collier Louise Cupac Brian Forsyth Tony Gaffney Matt Grimes Gerry Harkins Steve Harris Phil Lavelle Jai Wen Lee Neil Mellor Keith Mills Jeff Nelson Bob Nickless Steve Oxby Darren Pitts Rory Pollock Daniel Reece Paul Scoging Mark Simmonite Rob Stanton Ben Stevenson Rob Todd Tony Walters Chris White Rob Wilson Paul Wilson Ryan Wood Changes since the last revision are shown in red font.

The editorial contributions.

team

wishes

to

thank

all

contributors

Avoiding Defects – Revision D – July 2013

for

their

Relationship to other Documentation It is important that the Avoiding Defects booklet is used in conjunction with other technical guidance and reference documents.

Kier Technical Guidance can be found in the Kier Construction Technical Library.

Further (Inter)national technical standards can be obtained via ihs.com. The hierarchy of technical quality documentation is shown in the diagram below:

Hierarchy of Technical Quality Documentation

Avoiding Defects - Revision D – July 2013

Achieving Zero Defects – The Golden Rules • Check the specification and contract documents to ensure conformance to all requirements can be proven.

• Produce inspection and test plans (ITP) for all permanent work activities and that these reflect all the requirements and acceptance criteria of the specifications and drawings.

• Ensure detailed method statements and risk assessments have been received, reviewed and approved.

• Ensure personnel approving ITPs. and those carrying out tests and inspections are competent to do so.

• Ensure ITPs identify hold points for quality critical elements and that these include third party inspections where required.

• Ensure ITPs address interface products and components.

issues

between

trades,

• Include inspection and testing of products prior to delivery to site in ITP to ensure quality standards are being met for prefabricated components or to confirm performance.

• Use samples where possible both for client approval and as a benchmark for acceptable standard of workmanship.

• Record all incidents of sub-standard or incorrect work, obtain approval for rectification if required, ensure re-work is reinspected and records kept.

• Retain all completed records of inspections and tests.

• Ensure as-built information is obtained in the required format and check that it fully reflects what was actually built, including any changes or amendments.

Avoiding Defects – Revision D – July 2013

Contents 1.0

Levelling & Setting Out ....................................................... 11

2.0

Earthworks ....................................................................... 13

Soil Stabilisation ...................................................................... 14 3.0

Demolition........................................................................ 17

4.0

Piling ............................................................................... 19

Piling and Ground Improvement ................................................. 19 Piling Mat ............................................................................... 21 Bentonite................................................................................ 21 Retention Systems ................................................................... 23 Vibro-Compaction .................................................................... 23 Vibro Stone or Concrete Columns ............................................... 24 Dynamic Deep Compaction ........................................................ 24 Soil Mixing .............................................................................. 25 Anchors .................................................................................. 25 Piling - General ........................................................................ 26 Reinforcement cages, test holes & ground loops ........................... 27 Testing ................................................................................... 28 Driven Piles............................................................................. 28 Bored Piles.............................................................................. 28 Minipiles ................................................................................. 29 Continuous Flight Auger (CFA) Piles ............................................ 29 5.0

Deep Walling .................................................................... 30

Sheet Piling............................................................................. 30 Contiguous Piles ...................................................................... 30 Secant Piles ............................................................................ 30 Diaphragm Walling ................................................................... 31 6.0

Drainage .......................................................................... 34

7.0

Reinforced Concrete ........................................................... 37

8.0

Slipforming ....................................................................... 45

9.0

Pre-Cast Concrete/Casting Yard Operations ........................... 49

Planks / Hollowcore .................................................................. 49 Building / Structure .................................................................. 50 Stairs ..................................................................................... 51 Casting Yard Operations............................................................ 52 Avoiding Defects - Revision D – July 2013

10.0 Screed – Cement / Sand ..................................................... 53 Granolithic .............................................................................. 54 Under Floor Heating ................................................................. 55 11.0 Screed – Flowing (Pumped)................................................. 56 12.0 Temporary Works/Scaffolding .............................................. 58 13.0 Structural Steelwork .......................................................... 61 14.0 Metal Decking ................................................................... 65 15.0 Fire Protection .................................................................. 68 16.0 Swimming Pools ................................................................ 71 17.0 Grouting / Drypack ............................................................ 73 18.0 Brickwork / Masonry/Breather Membrane .............................. 75 19.0 Roofing ............................................................................ 79 Rooflights ............................................................................... 79 ETFE Roofs ............................................................................. 80 Metal Panel Roofs .................................................................... 81 Flat Roof – Asphalt / Single Ply .................................................. 81 20.0 Curtain Walling ................................................................. 84 Unitised Glazing ....................................................................... 88 21.0 Cladding .......................................................................... 90 22.0 Air Permeability ................................................................. 94 23.0 Cleaning Cradles / Maintenance Units ................................... 96 24.0 Plastering ......................................................................... 99 25.0 Plasterboard Partitions ..................................................... 101 26.0 Floor Finishes .................................................................. 105 27.0 Internal Render ............................................................... 108 28.0 External Render .............................................................. 109 29.0 Tiling – Floor & Wall ......................................................... 111 30.0 Suspended Ceilings .......................................................... 114 31.0 Painting and Decorating.................................................... 116 Wallcoverings ........................................................................ 117 32.0 Secondary Steelwork ....................................................... 118 33.0 Paint Finishes on Metalwork .............................................. 120 34.0 Carpentry / Joinery .......................................................... 121 35.0 Road / Hardstanding – Concrete ........................................ 124 36.0 Road / Hardstanding – Asphalt .......................................... 126 Avoiding Defects – Revision D – July 2013

37.0 Soft Landscaping ............................................................. 128 38.0 Sports Pitches ................................................................. 129 39.0 Raised Access Flooring ..................................................... 130 40.0 Acoustics........................................................................ 132 41.0 Furniture, Fittings & Equipment ......................................... 136 42.0 School Kitchens ............................................................... 142 School Food Technology .......................................................... 146 43.0 Lifts............................................................................... 148 Lift Shaft .............................................................................. 148 44.0 Utilities .......................................................................... 151 Electricity (MV–Medium Voltage LV – Low Voltage) ...................... 151 Telecommunications ............................................................... 154 Gas ..................................................................................... 155 Water .................................................................................. 156 45.0 Mechanical Services ......................................................... 158 Trench Heating ...................................................................... 159 Mechanical Installation ........................................................... 161 Building Management System .................................................. 162 Air Conditioning Units ............................................................. 163 Water Heaters ....................................................................... 164 Boilers ................................................................................. 164 Biomass Boilers ..................................................................... 165 Boiler Flues ........................................................................... 166 Radiators .............................................................................. 167 Sprinklers ............................................................................. 167 Smoke Ventilation .................................................................. 169 Attenuators ........................................................................... 170 Ductwork .............................................................................. 170 Grilles and Diffusers ............................................................... 171 Air Handling Unit ................................................................... 172 Fan Coil Units ........................................................................ 172 Fans .................................................................................... 173 Pumps / Booster Sets ............................................................. 175 Chillers................................................................................. 175 Insulation of pipework ............................................................ 176 Avoiding Defects - Revision D – July 2013

Underfloor heating ................................................................. 176 Chilled Beams ....................................................................... 178 Ground Source Heat Pumps .................................................. 178 Water Storage ....................................................................... 180 46.0 Electrical Services............................................................ 180 Electrical Services .................................................................. 180 Fire Alarm System ................................................................. 181 CCTV System ........................................................................ 183 Access Control ....................................................................... 183 General ................................................................................ 184 Electrical Procurement ............................................................ 185 Electrical Design .................................................................... 185 Installation/QA ...................................................................... 187 47.0 Commissioning ................................................................ 188 Water Systems ...................................................................... 190 Balancing and Commissioning .................................................. 192 Air Systems - Balancing and Commissioning .............................. 193 Electrical Testing.................................................................... 193 General Requirements ............................................................ 193 Required Competence ............................................................. 194 Fire Alarm / Life Safety / Cause and Effect ................................. 196 48.0 O & M Manuals ................................................................ 197 49.0 Working in Special Environments ....................................... 200 Rail ...................................................................................... 200 Nuclear ................................................................................ 201 Marine Environments .............................................................. 203 Cofferdams ........................................................................... 203 Tunnelling............................................................................. 205 Sprayed Concrete Lining (SCL)................................................. 205 Tunnel Boring Machines (TBM) ................................................. 205 Bridges and Bearings .............................................................. 206

Avoiding Defects – Revision D – July 2013

1.0 Levelling & Setting Out Most hire companies provide free training on the use of instruments.

They will also supply software which allows surveys to be downloaded to the computer; as-built drawings can then be overlaid on CAD for accurate records. Contact Kier IT to install software and KC Eng. on any CAD queries.

• Check the specification and contract documents Pre-construction • Ensure that both the national grid co-ordinates and the local grid are understood. Confirm that this has been used by the design team for the setting out information.

• Ensure your sub-contractor engineers conform to Kier standard for calibration of measuring & test equipment as a minimum, include requirements in the sub-contractor scope of works.

• Check that setting out information from different sources agrees. If not, clarify with designers.

• Ensure you clearly instruct in writing setting out information that sub-contractors can use i.e. drawings for construction.

• Make clear on inspection & test plan what surveys we expect subcontractors to carry out.

• Understand the tolerance involved in the survey/setting out and the interfaces of materials and their installation.

• Understand the accuracies of the instrument that is being used and whether compatible with the task being carried out.

• Investigate the use of new technology e.g. robotic EDMs & GPS which can negate the need for a chainman.

Construction • Follow only ‘For Construction’ contractors also comply.

drawings

–

ensure

sub-

• Maintain an up to-date drawing showing all primary control setting out data and locations.

• Regularly check primary controls positions.

Avoiding Defects - Revision D – July 2013

Page 11

• As-Built drawings must be made after every as-built survey and should be recorded in a folder (and saved on KIERdoc/MyKier).

• Main control datums should be used whenever possible for levelling works.

• Once master site datums are established these should always be referred to for the production of any secondary datums.

• Establish a secondary datum which is always checked back to a point of known level.

• When transferring datums from the main control points to secondary datums on or near to the building, where possible carry out a return traverse with equal fore and back sights.

• Rocking the levelling staff is a common method of ensuring the staff is plumb without a plumbing bubble. The lowest reading should be used. (This is when the staff is vertical).

• Another common way of ensuring the staff is plumb is to stand at the side of the staff and line it up with a known plumb object such as a column or corner of a wall. The engineer can direct the chainman to plumb the staff in the other direction (sideways) while looking through the level eyepiece.

• When setting out co-ordinated points or lines, always take the time to rough check with a tape measure, if possible, to an adjacent existing part of the building which you know is right.

Also take the time to make sure results ‘look right’ before releasing for use.

• Use the total station as a theodolite to set out columns and sight straight lines/offsets, instead of setting out individual column centre coordinates which invariably produces a row of columns which is not straight.

• Understand tolerances and fit. If a wall line is between two columns this is normally more critical than the exact dimensions. If you are not sure – ASK. • Digital machines can produce very accurate as-built drawings when linked to the correct software.

Reference documents: CIRIA C709 - Setting-Out Procedures for Built Environment

Page 12

Avoiding Defects - Revision D – July 2013

2.0

Earthworks

• Check the specification and contract documents • Consider and plan temporary works requirements Pre-construction • Agree with sub-contractor the site grid of existing levels before works start.

• Consider contours to reduce off site material – KC Eng can do 3D or 4D model including sequencing.

• Cut and fill exercises should consider using arisings from other excavations including foundations, service installations, piling etc when planning cut and fill activities. Consider an independent check of cut and fill model e.g. by KC Eng. • Consider breaking services, adjoining

site clearance, removing trees, undergrowth, out existing substructures, paving, drainage, live isolation, protection, monitoring movement of property/land.

• Do the site investigations apply to the whole site and provide sufficient information for the job to be priced / designed?

• Does the site investigation adequately quantify contaminated materials, type & extent of contaminants and whether the material can be kept on site?

• Does the site investigation consider the potential for UXO (Unexploded Ordinance) • Check waste tips are bona fide and check location and distance of tips.

• Clarify if materials arising from excavations or other activities can be used on site - weather is critical to this decision as the moisture content can be critical to compaction achieved.

• Consider management of ground water. Are temporary land drains to dewater required and can they be left in place after completion?

• If the ground is considered contaminated has a COSSH risk assessment with appropriate control measure been put into place? e.g. Has the use appropriate protective clothing/masks etc. been determined?

Avoiding Defects - Revision D – July 2013

Page 13

• If you are Storing Topsoil there is a specification required for the stockpile (Max 2m height / drained) • If the topsoil is to be sold on or removed at no cost from site it must meet the specification – Do you need to apply herbicide?

• Consider effect of vibration on existing structures.

• Plan logistics, pedestrian segregation and good haul roads.

• Resolve Road sweeping and wheel washing issues.

• Earthwork support required/approved by KC Eng. • Review requirements for edge protection and access.

• Ensure workspace around excavation is considered.

• Consider lime modification / stabilisation with specialist input.

Construction • Large plant fitted with CCTV cameras for rear visibility while maneuvering MUST be considered.

• Have permit to digs been issued following a review of working area?

• Ensure that you control and minimise Dust.

• Stop blocks must be added adjacent to excavations etc.

• Avoid work near the excavation surcharging it’s edge.

• Materials used within 450mm of finished level landscaping may be required to be frost resistant.

of hard

• Generally leave excavation 300mm above formation until immediately prior to blinding. Final formation should be cut with a ditching (not toothed) bucket.

• Consider use of geotextiles on formation prior to filling.

• Imported recycled material must comply with the WRAP Protocol and records of compliance obtained.

• Materials must be tested to confirm compliance with the specification.

Soil Stabilisation • Consider re-engineering soil when there is an imbalance with the cut and fill model and when existing site conditions don’t easily support high volumes of heavy plant movement.

• It is crucial from the outset to get the designers input.

Page 14

Avoiding Defects - Revision D – July 2013

• Ensure that the designers understand the reasons for and approve the use of stabilized materials.

• The designers can incorporate the treatment into their design to help make savings by reducing the specifications of roads and ground bearing slabs.

• Some Key factors to be considered before deciding on this solution are o What is the makeup of ground conditions o Are the soil reports accurate o Are there sulphates in the soil o What level of organic material is in the sub strata and how deep does it penetrate.

• A full suite of soils testing should be carried out.

• 6 weeks should be allowed for testing to ensure that soak/swell tests can be carried out over a 28 day period.

• Testing should be carried out for each 2500M3.

• All samples need to be representative of the level that is to be excavated ie. If the cut to the site is 1.5m samples need to be taken from this level.

• Ensure that the works are scoped correctly and performance criteria matching the specifics of use are set out from the onset to ensure that the engineered material performs correctly.

• Areas need to be specifically identified for Piling Mats, Haul Roads, and Hard standings and suitable performance criteria set to each individually • In sensitive areas stabilising machines with integral hoppers are used to reduce dust further.

• Compaction should take place within necessary moisture content range.

Avoiding Defects - Revision D – July 2013

Page 15

• Timing is crucial. Sufficient time needs to be allowed once the works have been completed before any trafficking of the surface is permitted.

• The quality checks need to align with the ITP’s. Below is a typical table of key compliance testing requirements.

Frequency of Sampling and Testing per layer a) Soil Suitability Checks and OMC b) Natural shear strength and CBR via hand held equipment c) Available Lime Report d) Lime and Cement Spread Checks e) Depth Checks f) MCV/m.c. Checks (final mix) g) Pulverisation Checks (final checks) h) Compaction Checks i) Soaked CBR / Total Sulphate / Sulphur j) Frost Resistance k) Insitu CBR

Sample Test layer Prior Testing Every 500m2

Frequency

per

By supplier Every 500m2 Every 1000m2 Every 1000m2 Every 1000m2 Every 1000m2 Every 1000m2 Prior Testing (1 sample) Every 1000m2

• A maintenance regime needs to be identified from the onset of the works. Key things that need to be reviewed are: o Drainage strategy o Compaction to capping layer o Levels of the underlying surface ensuring they are graded to falls to allow surface water run off. o Removing slurry and replacing the capping layer.

• Winter working conditions can be vastly improved on wet sites.

Reference documents: Eurocode 7 Geotechnical Design BS 5930 - Site Investigations BS 8004 - Foundation Design

Page 16

Avoiding Defects - Revision D – July 2013

3.0 Demolition Pre demolition • Before demolition ensure that Kier have been issued with relevant information including existing drawings, existing services drawings, service incomers from outside the site boundary and risk register.

• Review locations of services. Service diversions often require long lead times.

• Ensure that Kier obtains the latest Asbestos survey report.

When is the next survey due?

• If asbestos removal is indicated then there will need to be a formal notification to the relevant authorities and the approval period should be allowed for.

• A clean air certificate must be issued by the asbestos remover before any other works are undertaken.

• Ensure that you have confirmation from the sub-contractor that all the waste certification is in place and has been copied to site. The contractor must also supply details to Kier of the exact tips/waste stations so that these can be reviewed/inspected by Kier.

• Check whether surveys for Bats, Birds, Amphibians e.t.c are required. These requirements are often part of the planning conditions.

• Obtain and review existing information on water courses, obtain any details of local water extraction.

• Have all survey’s been completed for adjacent properties and public area i.e. structural survey, dilapidation survey, photographic survey.

• Review existing drainage information and confirm whether this is to be filled, removed or capped. Define strategy for this • Ensure that the full scope of works is agreed between the client and Kier.

• Remember that a discharge license and testing is required if water is to be removed from site.

• Formal notification is to be given for the commencement of the demolition operations and the approval period should be allowed for.

Avoiding Defects - Revision D – July 2013

Page 17

• Certificates for existing services to confirm they have been decommissioned are required prior to any works being undertaken.

• Confirmation required on restrictions for working hours, may be covered in the planning conditions.

• Method statement and risk assessment for all works must be approved by Kier and any party that requires this information, e.g. planning conditions can request this information.

• Ensure Temporary Works procedures have been approved by Kier Construction Engineering.

• If the demolition has a structural element has the demolition sequence been approved by the structural engineer and been checked by Kier Construction Engineering?

• Ensure that there is a waste strategy including material segregation and materials recycling for use on site / by 3rd party. e.g Concrete crushing / timber reclamation.

• It is essential to agree a strategy to ensure that the demolition area is segregated from plant or pedestrian access and the public. This must be integrated with the traffic management plan.

• Ensure that there are strategies for the control of dust and noise.

• Ensure that there is a strategy for the control of vibration.

• Arrange for the emergency services to meet on site to review access and emergency procedures.

• Check potential for re-use of existing foundations in new development.

• Ensure relevant party wall agreements are in place.

Page 18

Avoiding Defects - Revision D – July 2013

4.0 Piling • Check the specification and contract documents.

• Consider and plan temporary works requirements.

Piling and Ground Improvement There are many different forms of Piling and Ground Improvement.

Generally ground improvement is undertaken to improve the load bearing capacity of the existing ground whereas piling transfers the loads through the ground for end bearing in a competent stratum and/or generating shaft friction from the ground it passes through.

Deep walls to support loads and/or form ground retaining structures for basements can be formed from piles constructed adjacent to each other (contiguous piled walls),overlapping (secant pile walls) or continuous walls (diaphragm walls) the choice depending on a number of factors, but in particular the ground conditions.

Preconstruction • Is the site investigation adequate for pile design?

• Is pile probing required?

• Who is responsible for the pile design?

• Is design provided indicative? What is the basis for the design? Has the design been approved?

• Is there the potential for a more competitive foundation solution? (contact KCE) • Consider contract conditions and determine best way to procure piling sub-contract.

• Does the design require a test pile load test? If yes, this needs to be installed, cured and tested prior to commencing remaining piles.

• Review the test specification to ensure that the tests are effective especially deflection and recovery times. What is the frequency of subsequent tests. (ICE Specification for Piling) • Ensure that the testing requirements and arrangements are understood. Will they form part of the works?

• Agree with Designer/Building Control early, what percentage of piles will require testing and by what method.

Avoiding Defects - Revision D – July 2013

Page 19

• Who is to test the piles? (Must be BS/EN/ISO 17025 Certified by a UKAS accredited organization).

• Is the method of piling suitable for location/environment ground conditions?

• Have the requirements for a piled tower crane base been considered at pile design stage? (Contact KC Eng.) • Ensure subcontractor visits site well in advance of start to discuss access and storage. They may have requirements which require a specific build sequence.

• Check and comply with noise/vibration restrictions.

• Is there sufficient room for the piling rig around the perimeter of site particularly with regards to overhead restrictions and at site perimeter?

• Check piling rig movements for potential clashes with adjacent buildings / oversailing of other areas.

• Has space been allocated for the support crane, if required.

• Who is responsible for setting out the piles? be checked?

How many will

• If possible the setting out should be confirmed once the auger or pile is positioned?

• What positional accuracy is required for plan and verticality.

• Ensure that there is an adequate supply of materials including water supply.

• How will pile arisings be disposed of? Will they need treatment?

• Ensure piling logs completed and submitted on time.

• How will piles be broken down to required level? Consider use of proprietary bond breakers. Who is responsible for this?

• Who is responsible for any remedial measures required?

• Who is responsible if a pile becomes damaged or there are integrity problems? – Identify who to contact and who is to call the integrity tester to site as this can significantly delay the project particularly if they require a notification period. Is there a requirement for minimum number of tests/piles per visit?

Page 20

Avoiding Defects - Revision D – July 2013

Construction Preparation Piling Mat • Is pile probing required?

• Ensure the Piling mat design is considered early as complex piling mats can add considerable cost.

• Consider how the piling rig is to access the platform, (Check maximum gradient).

• KCEng. should be involved in the design or check of all piling mats.

• Upon completion a FPS working platform certificate will be required. Who maintains the platform?

• Has the piling platform level been determined to allow adequate reinforcement anchorage into foundations?

• Ensure that the mat material is as specified. Not all suppliers comply with the intent of the specification even though the test certificate may indicate compliance.

• A piling mat is a structure and must be constructed in the layers and to the levels specified in the design. Therefore ensure that the mat design is read and understood.

• Do not assume that because this is a similar mat to elsewhere that the construction is the same.

• Ensure water table is where the design has allowed for it.

• Ensure piling mat is well drained.

• Plan to bury key services in the mat such as power and bentonite supply lines to improve site access. Ensure routes of these are clearly marked at all times.

Bentonite Bentonite is a type of liquefied clay which is used to support piling and diaphragm wall panel excavations. The storage, use, treatment and ultimate disposal needs careful consideration during planning.

• Consider carefully the location of the bentonite plant in order to prevent the need to relocate as the works progresses.

• Consider carefully the recording of reconditioning requirements for the bentonite.

• Plan fixed bentonite lines early and incorporate into piling mat / trenches to minimise safety/ environmental concerns.

Avoiding Defects - Revision D – July 2013

Page 21

• Plan to ensure watercourses.

Bentonite

does

not

enter

identified

• Maximum time that bentonite may be left prior to concreting is 24 hrs. Where Bentonite has been in place for a considerable time and a crust is forming on the walls of the excavation consider reaming out excavation prior to concreting.

Construction • Establish responsibility for assessment of concrete quality.

• No in-situ piling to be carried out unless cube tank on site and working, or a fail-safe method for storage and collection is established.

• Ensure S/C is taking sufficient cubes. Ensure cube results are sent direct from testing laboratory checked, accepted or resolved and filed in QA file. Comply with the Concrete - Kier Technical Guide as a minimum.

• Can individual concrete deliveries be traced to particular piles and parts of pile if large diameter?

• Has a concrete back up plant been arranged and approved?

• Obtain cube results for any pre-cast piles.

• Obtain piling logs from sub-contractor daily.

• Carry out random checks, particularly on depth of pile. (Keep records).

• Ensure a daily work log is maintained and marked up on a drawing to minimise the risk of missing piles.

• Keep records of all piling activities including delays such as mechanical faults, concrete, follow on trades, material delivery, obstructions, etc.

The picture below illustrates shows the room piling rigs can take.

Page 22

Avoiding Defects - Revision D – July 2013

Retention Systems Drilled, pushed, vibrated or driven support systems (steel sheeting, soldier piles and lagging, tangent pile walls) cantilevered, braced or tied-back, installed in all types of soil to provide horizontal and vertical restraint of adjacent property during excavation and construction of below grade facilities.

Vibro-Compaction A site improvement technique for granular material, Vibro- Compaction uses proprietary designed probe-type vibrators to improve the density of soils to depths of up to 40 meters. VibroCompaction increases bearing capacity mainly to enable the use of shallowfooting construction, reduce settlements and mitigates liquefaction potential in seismic areas.

Avoiding Defects - Revision D – July 2013

Page 23

Vibro Stone or Concrete Columns Very weak, cohesive and organic soils that are not suitable for standard Vibro techniques can be improved by the installation of Vibro Stone or Concrete Columns. Beneath large area loads such columns can reduce settlement, increase bearing capacity, and increase slope stability.

Dynamic Deep Compaction Dynamic Deep Compaction is an economic site improvement technique used to treat a range of porous soil types and permit shallow, spread footing construction. Soil density is improved at depth by the controlled impact of a cranehoisted heavyweight (15-35 tons) on the ground surface in a pre-determined grid pattern.

Dynamic Deep Compaction is also successful in improving the properties of landfill material for such uses as highway construction or recreational landscaping.

Page 24

Avoiding Defects - Revision D – July 2013

Soil Mixing Typically used in soft soils, soil mixing is the introduction of an engineered grout material to either create a soil-cement matrix for soil stabilization, or to form subsurface structural elements to improve the ground to facilitate tunneling or support building loads.

Soil mixing can be accomplished by many methods, with a wide range of mixing tools and tool configurations available.

Special considerations for Soil Mixing • It is difficult to predict the final result of the mixing in specific areas. Trial bores which are then dug out and tested may be required in order to ascertain the correct controlling parameters to be used.

• The composition of returning spoil is only a partial indication of the effectiveness of the soil mixing.

• Once parameters are ascertained they need to be closely controlled particularly in the case of the back pressure values.

• There is a high degree of reliance on operator necessitating the need for training, experience independent observation and verification.

skill and

Anchors Rock and soil anchors offer an economical solution to temporary or permanent stability or support requirements. Designed to withstand lateral and/or uplift forces, these structural members are typically used with temporary, deep excavation support systems, as a part of permanent retaining walls, for dam stabilization, or to resist wind-produced uplift forces.

Avoiding Defects - Revision D – July 2013

Page 25

Soil Nails When soil nails, usually relatively short steel bars, are inserted into the face of a soil slope, and the surface is then sprayed with gconcrete (shotcrete) with or without additional geo textile and a zone of stabilized earth is produced. This zone performs like a gravity retaining wall to support the unreinforced ground behind. Soil nail walls are used for embankment stabilization, or for excavation support.

The design and construction of such walls is a specialist activity. The particular maintenance requirements also need to be determined and agreed with the ultimate client.

Piling - General • Do mixes comply with specification – mix, minimum cement content, sulphates etc? (keep records). Has the mix design been approved?

• Ensure that plumb of the piles is checked / maintained.

• Survey as-built ‘ground level’ pile positions within 48 hours – Produce as built drawings for all piles.

• If applicable be aware of lightning protection path via a dedicated bar (painted to identify its use) or via the cage.

Ensure column, cap and pile are linked.

• Do we have an adequate method statement for cutting down piles? Ring muncher / hydraulic splitter / Elliott Method to be utilised rather than manual breaking with a jack hammer.

(HAVS) • If the ‘Elliott method’ or equivalent has been considered for cutting down the piles it requires sleeves on reinforcement, so groundworker and piler must agree before start. Be aware of the Elliott patent.

• Consider blinding around all piles before cut down.

• As-builts - weekly joint review subcontractor is recommended.

Page 26

of

Avoiding Defects - Revision D – July 2013

piles

by

Kier

and

• Check all piles have been cast.

• Check specification pile position tolerance (usually +/- 75mm).

• Check whether the construction of guidewalls is required.

• Ensure guidewalls are properly surveyed and QA complete before use.

• Ensure that guidewalls are backfilled as soon as possible after construction to remove a possible safety hazard.

Reinforcement cages, test holes & ground loops • Check reinforcement cage is as per design.

• Ensure sufficient spacers on pile cage.

• Check that spacers will give the full coverage required and are not bent or damaged.

• Consider methods to avoid cage float/sink within the piles e.g. extra “feet” added to the cages.

• Use of proprietary couplers e.g. “lenton” to join multiple cages requires good positional accuracy to be maintained at the ends of the cage in order for the cages to join easily.

• Where cages are delivered in multiple sections consider the construction and use of a “rat hole” (dummy dig) in order to preassemble the cages – especially where space / time is tight.

• Ensure cage can be lifted without deformation. Strengthen if necessary.

• If tubing for geothermal or tests are required check test requirements e.g. for ultrasonic testing ensure that these are considered in the design of the cage.

• Do not skimp on the tube joining methods as the tube needs to be watertight and stop concrete ingress (consider using tube fittings / threaded pipes.

• Protect the working end of the tube while concreting.

• Allow sufficient time for ground loops to be installed and secured to the cage.

• Ensure both ends of the ground loop are capped/protected during the concreting process.

Avoiding Defects - Revision D – July 2013

Page 27

Testing • Determine testing requirements early as method of testing may require additional modifications or attachments to the reinforcement.

• Ensure all piles are checked/tested as required and report accepted prior to pile cap installation.

• Agree notification period for tester well in advance.

• Ensure that the test report reaches a conclusion on the pile acceptability.

• Understand testers requirements – some tests require access to water and power to be available.

Driven Piles Friction and end-bearing piles ranging from lightly-loaded wood piles to high-capacity, concrete- filled steel pipe and H-piles driven in all types of soil to depths up to 50 meters, to provide foundations for building and infrastructure projects.

The lack of arisings make this particularly attractive as an option.

Bored Piles Bored piles use augers to create a void which is then filled reinforced concrete.

The void must be supported during drilling and an oversize casing is often installed ahead of the auger in order to provide this. Alternatively Bentonite is sometimes used as a support fluid. The choice depends on the ground conditions.

Page 28

Avoiding Defects - Revision D – July 2013

Minipiles A type of bored or driven pile for low headroom applications. They are often used for underpinning of settling or deteriorating foundations and support of footings for increased capacity. Minipiles are particularly useful where headroom is limited or access restricted. These small diameter, friction and/or end bearing elements can support ultimate loads of up to 350 tons in a competent stratum.

Special considerations for Bored / minipiles • Review method for casing removal (if applicable) with H&S Manager.

Continuous Flight Auger (CFA) Piles The CFA system provides a quiet, low vibration form of piling which is ideal in built-up areas and is quick to install. CFA can be used in most soils.

Constant monitoring is essential to the success of the system.

Special Considerations for CFA Piles • Ensure positive pressure while concreting to maintain pile profile.

• If cases are used deep cases usually require vibrating.

• The reinforcement cage is plunged into the recently pumped high slump concrete rather than the other way around – Avoiding Defects - Revision D – July 2013

Page 29

therefore check that the cage is sufficiently robust to withstand these construction forces.

5.0 Deep Walling General Considerations • Is there a need for a guide wall to be installed?

• Has the design been checked for the short-term temporary condition prior to commencing excavation?

Sheet Piling Drilled or driven support systems (steel sheeting, soldier piles and lagging, tangent pile walls) can be cantilevered, braced or tied-back and are installed in all types of soil to provide horizontal restraint of adjacent ground during excavation and construction of below ground facilities.

Special consideration for sheet piling • Do sheet piles require an approved welding methodology and testing procedure.

Contiguous Piles Contiguous piles is the name given to standard piles installed close enough together to form a retaining wall. The gap between the piles is dependant on the ground conditions, water table and retention needed.

Special consideration for contiguous piling • Contiguous piling does not impede water flow from permeable ground.

• Do contiguous piled walls require temporary propping during construction? Consider position of walers – can capping beam be used?

Secant Piles Secant piles are piles installed in such a way as to form a continuous watertight wall. First the Female piles are installed and then the male piles are installed in such a way that Page 30

Avoiding Defects - Revision D – July 2013

they bite into and join the adjoining female piles turning the female pile into a secant shape. Reinforcement requirements differ depending on the scheme chosen and can involve use of cages for the male pile only or both male and female piles, the latter commonly using steel column sections as reinforcement.

Diaphragm Walling Diaphragm walling is a type of piling construction creating reinforced concrete panels in the ground by using a using a grab to dig a trench between guide walls. Bentonite is used as the support medium during the dig. Stop ends and maybe a waterbar are then installed at the ends of the trench, the reinforcement cage installed and the trench is

then filled with concrete tremied in the bottom displacing the bentonite as the pour proceeds.

Diaphragm walls have much the same considerations as Piling so it is recommended that the section on piling is also consulted.

Special Considerations for Diaphragm Walling Design • Ensure there are plenty of “starter” and “end” panels to ensure flexibility.

• Carefully review drawings for construction practicality including consideration of lap lengths, cage joining process and positioning of ancilliaries such as sonic log tubes and thermal exchange tubing.

• Challenge any overcongestion of reinforcement – it may be possible to reduce this e.g. by increasing wall thickness while being more economical.

• Ensure that there is a large enough uncongested area in the reinforcement to fit a tremie pipe.

Avoiding Defects - Revision D – July 2013

Page 31

• Liaise with the designer with regard to stopend and waterbar details. Note that it is impossible to take the stopend/waterbar to the bottom of the pile without overdig due to grab bucket swing radius.

• Liaise with designer to ensure that the optimum panel length is chosen.

• Consider how rebar cages are to be joined. Beware of a design stating “or similar” for jointing systems.

Construction • Plan for two shift operation – often a panel will take longer to complete than a standard shift.

• Ensure all obstructions are removed and if in doubt probe.

• Ensure debonding requirements are clear from start.

• Protecting starter bars in the wall with box outs is a good idea but make sure that these can be removed when necessary.

• Often rebar cages are very large – consider their lay down requirements.

• Ensure cages are sufficiently robust to withstand lifting into position.

• Consider safe methods of joining cages.

• Consider jointing of sonic tubing. Ideally joints should be threaded.

• Trenching plant will need to be commissioned before use. Allow for this in terms of space and time.

• If geothermal pipework is required in the design be aware that this can take a while to install.

• Always arrange for cages to be inspected before delivery to site.

• Consider lifting points in the design.

• Consider requesting that the cages are “preslung” to avoid working at height issues on delivery.

• Ensure good communications with concrete supplier to ensure concrete supply is continuous.

• Review tremie embedment results and ensure contractor frequently “splits” the tremie.

Page 32

Avoiding Defects - Revision D – July 2013

Reference documents: ICE Specification for Piling & Embedded Retaining Walls (SPERW) Concrete – Kier Technical Guidance Note TGN 5 – Concrete Advisory Service TGN 9 - Preparing, curing & Testing Cubes TGN10 – Recording Concrete Cubes Correctly TGN 10 Form 2515a – Concrete Cube Results Analysis Example

Avoiding Defects - Revision D – July 2013

Page 33

6.0 Drainage • Check the specification and contract documents.

• Consider and plan temporary works requirements.

Pre-construction • Prior to commencing works, obtain permission as required, for discharge into existing drains for both temporary and permanent discharge. Discharge into the public sewer will require a licence to be bought from the Local water company, this requires a cheque to be raised and application form to be completed (normally by the designer).

• Be aware of inspection, test and witnessing requirements from Client/Building Control / Adoption Authority.

• Ensure Pipes / joints do not clash with Foundations / rebar / other services. Falls must be maintained.

• Rockers/puddle flanges should be detailed at structures and manholes?

• Ensure the manholes are large enough for the number of branches detailed.

• Co-ordinate manholes with external hard and soft landscaping.

• Check the drawing details are compatible with Local/Water Authority Requirements.

• Consider implications of paper hand towels at schools and size of pipes.

• Check the Local/Water Authority details are compatible with drawings.

• Check invert levels of all outfalls before design/work starts.

• Downpipes must include adequate provision for expansions.

• Review drainage design (for compatibility between the Architect and the Structural Engineers drawings. Pay particular attention to manhole covers, gulleys and surface drains as these may affect the final floor finish.

Construction • Keep written records of all equipment provided, particularly service/calibration records.

• Keep written records of the training of all staff involved.

Page 34

Avoiding Defects - Revision D – July 2013

• Ensure that method statement/entry procedures is suitable for confined spaces. All personnel entering the confined space must be confined spaces trained.

• Ensure that the orientation of the manhole is correct including step irons (If allowed) in relation to kerbs and cover (e.g.

Paving).

• Is type and thickness of pipe bedding correct?

• Check that run is straight, horizontally and vertically.

• Does the bedding material require special measures because of weak support? (e.g peat) • Ensure trench backfill material and method of compaction is to required specification.

• Take pipe wall thickness and collar size into account when calculating dig levels, especially for large diameter concrete pipes.

• Ensure trench widths do not exceed design assumptions, comply with Temp Works procedures.

• Ensure articulated joints in concrete surrounds are accurately formed and all round the pipe.

• Ensure that all runs, manholes and gullies are kept clean and protected from debris.

• Are pipes and manholes recommendations?

installed

to

manufacturer’s

• Ensure correct manhole covers are installed (load, finish & seal).

• Ensure that invert levels are checked and recorded before backfill.

• Carry out specified test (air/water) before and after backfill. & record / get signed off.

• Be aware when backfilling trenches that lumps of concrete / hardcore are not allowed to fall onto the pipes or are in close proximity as they may cause the drains to fracture.

• Bench manholes before putting covers on thus reducing confined space access requirements.

• In very shallow gradients, settlement will create ponding at the bottom of the pipe. Use a drain laser for accuracy.

Avoiding Defects - Revision D – July 2013

Page 35

• Any change in direction (particularly pumped systems) must have an adequate thrust block. Ensure these are cast against firm ground.

• Do not pump silty water into drainage systems.Use settling tanks or other methods to remove silt. (Obtain approval for any water discharge into drainage systems). The SHE department will advise.

• For gullies that have to be cast in with the concrete slab and no box out formed consider how these are to be held secure and who is to ensure that they are?? The groundworker usually installs the gully; the concrete frame contractor places the concrete so who checks that they are in the correct location and to the correct datum?

• Install gullies 5-10mm low and dish around to ensure the gully is located in a low area. Where possible create box outs and install gullys during finishing works.

• Always ensure open ended pipes are capped (water tight) to prevent debris entering the drainage system, particulary cementitious slurry screed.

• Ensure CCTV surveys are carried out and checked for compliance at completion of the sub-contractors works and prior to handover.(This must allow for undertaking any remedial work and resurvey).

Page 36

Avoiding Defects - Revision D – July 2013

7.0 Reinforced Concrete • Check the specification and contract documents.

Pre-construction • Ensure a full specification has been issued.

• Any opportunity with Group trading agreements e.g. concrete supply?

• Bending schedules are often omitted from Engineers services – check who is providing them.

• Ensure anti-crack bars are detailed to each void - ideally not as a ‘typical’ detail unless it is repetitive.

• Eurocode 2 requires different lap lengths to BS8110. Ensure these are provided as specified by the designer.

• Have mix designs been submitted and approved by structural engineer and designer?

• Do we have a back up plant? (Keep records.)

• Review and agree tower crane allocation. Ensure crane size, specification, durations,location, working hours, banksmen and slingers are all clear and specified in contracts.

• Ensure Tower crane duties are compliant with the weight of concrete skip proposed, o

1m3 skip approx. 3.2t

o

2m3 skip approx. 6t.

• Check travel time to site from batching plant especially in rush hour traffic.

• Ensure an adequate clean storage area is available before reinforcement is delivered.

• Check that the reinforcement supplier has a CARES certificate for all the types of reinforcement being supplied and that the delivered reinforcement complies.

• Beware of rebar deliveries in bulk / FIBCs/tote bags (RED TOP).

• Schedule the rebar to allow prefabrication (Especially on walls) if practicable in order to reduce working at height issues and make programme gains (RED TOP).

Avoiding Defects - Revision D – July 2013

Page 37

• If prefabbed rebar is to be lifted who carries out the assessment on whether it is safe to lift? The Engineer and AP must agree the lifting points, structural ties and method of lifting, the steel fixing foreman must ensure each cage is constructed to the design.

• Consider access for vertical elements with regards to fixing rebar, fixing cast-in items and concreting. Is a proprietary system available i.e. GASS/DOKA and will this be acceptable for all requirements?

• Is the cube curing tank on site and operational, if required for identity testing? Check availability of all other test equipment • Is cube shed heated? Low 7 day results will be obtained if the cubes are not protected from low temperatures in the first 24 hours.

• Is the cube tank large enough for all the cubes.

• The preference for concrete testing is for an independent test house to be used, If the concrete supplier is used then the supplier must be examined to ensure that they have robust procedures for this activity.

• All cube tests must be carried out by a test house / facility accredited by UKAS to BS/EN/ISO 17025.

• Is there an opportunity to use group trading agreements? E.g. concrete supply.

• Is the pour thick/deep? (>1 metre) Consult K C Eng. For advice on control of heat of hydration.

• Has consideration been given for concreting in cold or very hot weather? (YELLOW TOP) • Check on requirements for formed finishes.

• Finishes A & B in BS 8110 are very subjective. (Usually an additional narrative is required to define fully). Construct a sample panel or refer to regional samples. Check the sample panel is not over the requirements of the specification and represents the minimum acceptable standard.

• Make sure any agreed standard is maintained.

• For fair-faced concrete identify what spacer blocks are specified. Tricktrack (plastic spacer bar) is not usually acceptable and concrete blocks have to be used.

• Upstand beams do not hinder table forms, downstand beams do.

Page 38

Avoiding Defects - Revision D – July 2013

• Opt to use pre-cast or steel for stair construction rather than in-situ concrete.

• Cement with a high content of PFA (Pulverised Fly Ash) will have a delayed cure.

• Test a sample of the dust sealer/inhibitor prior to its application. Some types emphasise making good.

• Do not underestimate the time it takes to co- ordinate and install M&E and cast-in items within the pour and at what stage. Do they require just the bottom mat to be fixed to install large items/floor boxes or to thread large sections of conduit?

• Assess access requirements during construction at an early stage particularly with complex structures.

• Ensure adequate working space to the outside face of the perimeter wall when construction basements. A metal shutter can be used and bolted/secured from inside the structure if there is restricted access.

• Consider using Expament as a stop end. If this is used consider having spare stock on site to form a temporary stop end if there is a problem during the pour Prepour • Has temporary edge protection fixing requirements been resolved. Consider proprietary systems e.g. Combisafe or KGuard.

• Consider movement and deflection of finished beam. Is there a need to precamber?

• Review/approve layouts for day joints, expansion joints, board layouts, dywidag holes and dywidag hole finish (flush/recessed).

• Have pour joints, flying starters, corner bar, couplers and postfixed starters been agreed?

• Ensure the stop-end is located at a sufficient distance from the end of the rebar to allow the specified lap. Stop end location to be agreed with Engineer – normally it is required at 1/3 span.

• Check the finish to be applied to the concrete – i.e. if a bond test is specified for the concrete then laitance on the concrete will have to be removed. Who is to do this operation?

Avoiding Defects - Revision D – July 2013

Page 39

• Check on any subsequent finish to be applied to slabs before pouring. Most screeds require a flat finish to the concrete, e.g. skip float.

• Do not overwork power floated finishes. Is a skip float finish acceptable?

• If power floating consider noise levels.

• Have adequate spacers / chairs been detailed (within the bending schedule) to support top mat, especially on deep beams and slabs.

• Is the pour to level or thickness?

• Has propping and back propping been provided in accordance with the formwork design and in line with temporary work procedure (permit to load / strike).

• The concrete pump has significant ground loadings has the ground bearing capacity been assessed? Also refer to the Specialist Procedure regarding concrete pumping.

• Ensure service ducts and openings in slabs are co- ordinated and built in.

• Is there a requirement for cast in fixings e.g. lift shaft guards.

Concreting • Ensure a pre pour check is carried out to include formwork, falsework, spacers / chairs,any cast in items, lightning protection and joint preparation.

• Check release agents are compatible with required finishes.

Must be neutral pH. • Beware over application of release agent on formwork.

• Check correct spacers / cover requirements have been used and that the steel will not move or spacers become displaced during the pour.

• Particular care should be taken to check that the reinforcement conforms to the details and that the cover, lap lengths, and starters are correct.

• Ensure all delivery tickets are checked against requirements before the concrete is placed in the pour. The ticket must state conformity to either BS 8500 or BS206-1 to be valid.

• Give each mix a unique reference number to aid checking.

Page 40

Avoiding Defects - Revision D – July 2013

• Establish and maintain a regime for checking consistency. It is no good checking consistency half way through a pour.

• Where the measured consistency is outside the permissible ranges and if it is permitted an agreed and controlled amount of water may be added to the concrete prior to discharge. The water addition must be recorded on the delivery ticket, the mix remixed thoroughly and the concrete sampled for strength identity testing. Any water added shall not result in the maximum water/cement ratio being exceeded.

(Note : Addition of water invalidates the supplier’s certification on the delivery note.)

• Where required by the specification, the concrete should be sampled, cubes made and cured to specification. Where early striking is required, additional cubes should be made and match cured in the same conditions as the pour. (Keep records). Note : refer to KC Eng. for Kier best practice advice on concrete sampling, this often exceeds the specification.

• Do not move concrete with a vibrator.

• Avoid burn marks by not resting a vibrator on formwork.

• Consider method of joint preparation as scabbling has issues with HAVS. – look at alternatives.

• Joint preparation is very important and should be carried out with equipment suitable for the age of concrete.

• Joint preparation should be done across the whole section (except possibly the outer 15-20mm).

Post Pour • All concrete must be cured properly. Ensure that curing concrete is protected from adverse weather conditions at all times.

• Carry out regular coverage checks on spray-applied membranes.

• Ensure that post pour surveys are carried out to include dimension, level, flatness, starter bar positions, remedials, curing and cold weather protection . if appropriate. Surveys to be carried out within 48 hours.

• Remedial work required must be agreed with the specifier (Refer to NCR procedure) and then carried out as soon as practicable.

Avoiding Defects - Revision D – July 2013

Page 41

• Closely monitor concrete test results for compliance. (Within 5 days of test age.) Take early action where non compliance is indicated.

• Ensure that 28 day test results are formally issued by the test house on letterheaded Paper complete with signature.

• Protect/cover fair faced concrete to prevent rust staining from rebar.

• Limit the amount of time fair faced boards and rebar are exposed to the elements prior to pouring and prevent foot traffic over soffit boards.

• Pour on a Friday rather than leaving it over the weekend to rust and stain the boards.

Post-Tensioned Concrete • Make cubes and match cure on site adjacent to the pour. This is often a mandatory requirement from post tension installers.

Waterproof Concrete • Has the type of waterstop been specified and accepted?

• Does the basement need to be vapour proof?

• Has sufficient ventilation been designed?

• Determine whether damp patches are acceptable?

• Do not assume that ground water will stay as it was before construction.

• Bituthene or similar needs perfect conditions for application.

Beware of creases and joints and protect before backfilling.

This must be kept under load to work long term.

• Consider bentonite based systems.

• Waterproofing systems which are not held in place by water pressure rarely work properly.

• Consider High Performance Plasticisers.

• Consider cement replacement to minimize use of CEM 1.

• Ground granulated blastfurnace slag (GGBS) reduces hydration heat thus reducing cracking BUT has a lower tensile strength.

• If 400kg or more of cement is used on a one sided wall of 500mm or more, monitor heat in first pour – K C Eng. will advise.

Page 42

Avoiding Defects - Revision D – July 2013

• With liquid applied membranes ensure that the preparation, thickness, penetration details, corner details, protection are as detailed.

• Ensure that the method statement for making good bolt holes is adequate. Consider shutter ties.

• Check manufacturer’s recommendations re: sustainability and installation.

• Do not store applied materials, liquids or otherwise, in cold conditions.

• Ensure size of pour is compatible with amount of reinforcement detailed.

• To minimise shrinkage, wall bays should be limited in size and cast sequentially to a plan.

• Consider using thermocouples to monitor temperature and so avoid thermal shock.

• Insulation may be required to control temperature differential.

• Shutters must be grout tight. Dampen joints before concrete pour.

• Good compaction is essential for watertight concrete – check spec.

• Hydrophilic waterbars will not perform fixed to a rough surface they should ideally be placed in small rebates, or applied to a smooth trowelled margin in the centre of the section and fixed to manufacturer’s recommendations.

• Any honeycombing, even if slight makes the waterbar useless.

• Take care not to damage waterbars when striking formwork or preparing joints.

• Good curing is essential.

• Check Laps lengths are as required.

Reference documents: BS EN 206: Part 1:2004 Table A.13 Concrete Mix Designs BS 5328: Part 1:1997 Concrete Cube Testing Requirements BS 8110: Part 1:1197 Minimum Cover to Reinforcement Concrete – Kier Technical Guidance Note TGN 5 – Concrete Advisory Service Avoiding Defects - Revision D – July 2013

Page 43

TGN 9 - Preparing, curing & Testing Cubes TGN10 – Recording Concrete Cubes Correctly TGN10 - Form 2515a – Concrete Cube Results Analysis Example

Page 44

Avoiding Defects - Revision D – July 2013

8.0 Slipforming Check the specification and contract documents Consider and plan temporary works requirements Preconstruction • Check the specification and contract documents • Inform and involve designers in use of Slipforming at an early stage; avoid adaptions to the form where possible and standardise the form, openings, embedment’s etc to make the operation smoother (avoid walls under 200mm thick) Can the core be enlarged to take in additional walls?

• Does the designers programme coincide with the use of slipform?

• Full height core information should be issued circa 12 weeks prior to the start of the slip, including all tie in’s.

• Are there any restrictions on working hours and noise? (Noise monitoring required for out of hours working?)

• Have the various concrete mix designs been approved by the structural engineer and designer?

• Carry out a site test to determine performance in current conditions (Do not rely on previous mix performance results).

• Agree the concrete quality with the sub-contractor / architect (will not be Type B) • Has the tower crane allocation during the slipform been reviewed and agreed? Ensure crane size, specification, durations, location, working hours, banksmen & slingers are all sufficient.

• Consider the use of a pump and placing boom to free up cranes for other site activities (Can this be used out of hours or is it too noisy?)

• Ensure the sub-contractor has a robust repairs procedure in place before commencing; repairs can take place from hanging deck but the window of opportunity will be small.

• If 24hr Slipforming ensure there is a back-up concrete supplier in place.

• Consider access / egress from the slipform and logistics surrounding it. A passenger / goods hoist is strongly Avoiding Defects - Revision D – July 2013

Page 45

recommended. (Haki stair case as secondary means of escape.)

• Has pre-fabricating formwork off site been considered to further reduce programme?

• Temporary stability of the core needs to be confirmed - If temporary bracing is required this will need to be designed by the temporary works engineer & may require cast in embedment plates (KCEng. will normally only comment, not sign off).

• Have you considered allowance for 24hr attendance / call-out of an electrician?

• Consider separate power supplies for the slipform rig and any powered access and ensure there is a back-up generator in place.

• Agree a stringent form & deck cleaning regime to be agreed prior to start.

• Expect lots of visitors. How will this be managed? Group sizes?

Frequency?

Construction • Has the commencement date of the slip form been considered properly?

• Allow time to install the hanging deck and plan so that it will be installed during the day shift.

• Agree the tolerances for the starting position of the formwork between the designer, engineer and sub-contractor; this may have to be more stringent than the vertical tolerance allowed in the specification as the slipform tolerances have to be taken into consideration.

• Maintain an exclusion zone around the perimeter of the slipform and provide covered access for slipform engineers to access auto plumb points.

• Consider involving engineers and management within the company with previous slipform experience.

• Has the control of quality been considered? Plan the ITP early to cover several full checks per shift and ensure that any subcontractor is doing the same.

• Prepare as-builts all door openings, embedments, penetrations etc from the hanging deck; this will allow planning of any Page 46

Avoiding Defects - Revision D – July 2013

necessary changes / repairs which will need to take place well in advance of reaching that level with the intermittent slabs.

• Review how the flow of materials is to be managed. This should be done in such a way that there is always sufficient materials on the rig, yet not enough to impede work due to the limited space.

• Avoid back to back reinforcement continuity strip if possible; if required ensure special slim strips are scheduled & that minimum cover will be achievable on both faces of the wall.

• Concrete should be placed in the shutters in no more than 300mm layers.

• Have you considered the lighting and power requirements for the rig?

• Ensure no materials / rubbish are stored below the slipform as they are a fire hazard; debris netting, Monoflex (Kier marketing opportunity) etc should all be fire rated.

• Consider ply hoarding to working platform in lieu of scaffold handrail & monoflex.

• Consider use of hydraulic cutters for rebar to reduce hot works.

• Rebar drawings will need to be scheduled / rescheduled to suit the slipform operation (staggered 6m long vertical rebar, corner details, positioning of the yokes etc).

• Rebar drawings are drawn per floor but only around 1m of horizontal rebar will be available for inspection. The best way to ensure all horizontal members are included is to make sure vertical spacing is not exceeded.

• Does cover to rebar change at different levels?

• Ensure drag spacers are changed to suit and removed and cleaned regularly to avoid vertical streaking.

• Are cast in plates to support steel work present? How will these be supported? (Manual handling.)

• Ensure all non-standard embedded items are on site, checked, formally handed over and stored properly in advance of being needed.

• It is very difficult to maintain the quality of cast in halfen channels, conduit etc due to the moving shutter.

Avoiding Defects - Revision D – July 2013

Page 47

• Have staffing arrangements been considered? Consideration should be given to shift patterns, management, engineers, tower crane drivers, banksman, the European directive on working hours and the labour split for day / night shift.

• Will public transport affect the ability of labour to get to site for shift changes? (Sunday / Bank Holiday transport.)

• Access between decks is via ladder; ensure trapdoors are fitted, have self-closers on them and are maintained.

• Have you considered the disassembly of the rig? How will the last operatives get down? How will edge protection be maintained?

• Due to the large exclusion zone required disassembly is recommended to be programmed to take place on a weekend so as not to affect other site activities.

Reference Documents: The Concrete Society – Slipforming for vertical structures (2008) Avoiding Defects - Chapter 7.0 - Reinforced Concrete Kier Doc – One Reading Central Slipform Evaluation (2008)

Page 48

Avoiding Defects - Revision D – July 2013

9.0 Pre-Cast Concrete/Casting Yard Operations • Check the specification and contract documents Planks / Hollowcore Pre-construction • All planks acting as temporary formwork are temporary works and must comply with the Kier Temporary Works Procedure.

• Be clear about extent of design responsibilities including mix designs etc.

• Have builder’s work holes been detailed?

• What finish is required to top of slabs? Composite slabs will require a bond between the plank and the topping.

• What camber will the beams / slabs have? Does this allow sufficient thickness of finish if camber does not come out?

• Ensure lifting points are design and agreed.

• What placing tolerance has been allowed for in lengths of units?

• What about nets, airbags etc?

Construction • Ensure hollow core planks are dry and not holding water, make sure weep holes have been detailed and are clear to let water out.

• Positioning of lifting points may have closed part of the core preventing water getting into the weep hole.

• What soffit to the slab is required? Is it exposed or not?

• When placing slabs onto masonry, use sand / cement bedding to allow for unevenness in the level of the support.

• Avoid impact damage to slab or support.

• Are there other minimum dimensions required as well as bearing e.g. gap between units etc?

• Ensure gaps between bottom edges of units are sealed/grouted before concreting, and that the correct concrete is used to fill the space.

• Ensure minimum bearing condition are met as build-up of tolerance and support position tolerance can reduce the achievable bearing.

Avoiding Defects - Revision D – July 2013

Page 49

• Structural topping requires careful curing due to thin concrete section.

• Planks should be pre-soaked prior to placing concrete topping.

• Ensure grouting to the end of the planks is done correctly.

Poorly executed grouting can allow water to get to the core.

• Ensure back propping has been considered when placing the planks and structural topping. Back props should not be removed until the structural topping has reached the designed strength.

Building / Structure Pre-construction • Allow time from completion of groundworks (ground beams) to allow for survey and setting out to be completed.

• Make sure power and water are supplied to the slab or ground beam area prior to the build starting.

• How will the subcontractor order be placed; design, supply and erect or design and erect only?

• Ensure specification for finish is in place i.e. type C. • Produce sample panels for sign-off prior to commencing full production.

• Ensure precast manufacturer is aware of quality required as struck and any subsequent finishing works • Continually monitor off-site production. Expect quality to improve during the process.

• Check colour consistency.

• Be aware of curing procedure and storage requirements at the factory.

• Consider buying moulds when sufficient quantities to benefit.

• Ensure casting moulds are replaced when they become worn.

• If design includes repetitive modules, consider producing a full mock-up including fit-out, in order that design or detailing errors are highlighted.

• Consider who is to supply and install cast in items.

• Fully understand the manufacturing tolerance of cast-in items and how this affects the cast surface.

Page 50

Avoiding Defects - Revision D – July 2013

• Ensure adjacent cast items are aligned as they may require holding in a jig during casting. Shutter magnets can allow slight rotation.

• Consider effects of any finishing processes on cast in items. e.g. effect of acid etching chemicals.

• Ensure builders work drawings are available prior to M & E installation due to lead-in period.

• Check that dowel bars cast into the foundations are correctly positioned and of the correct length. Tolerance requirements can be tight to correspond with tight factory tolerances on the pre-cast.

• Co-ordinate future fixing works with pre-cast panel ties. These cannot be cut so if incorrect, they need to be repositioned.

• Underfloor heating tails must be correctly positioned within the pre-cast element. Therefore ensure heating specialist has an attendance at pre-cast yard.

• Is there an interface with M&E design to avoid drilling and cutting works later? Can all details or items be cast in?

• Consider on-site propping method and location to avoid services e.g. underfloor heating pipes.

• Where possible ensure edge protection is fitted to floors and stairs prior to lifting.

• Consider if there are any special delivery requirements.

• How is the finished works to be protected?

• How are the units to be stored off site?

• Set up and agree a sample finished room/area Stairs • Ensure Stairs are bought early and installed with frame.

• Understood the required finishes. e.g. anti-slip.

• Are stair nosings required to be cast in?

• Is trace heating required for external stairs?

• Do you need nosings cast in?

• Consider how handrail is fixed.

• Can temporary handrails be installed with the stair (or brackets for permanent)?

Avoiding Defects - Revision D – July 2013

Page 51

• Do you need temporary protection (must be fire rated & anti slip).

• Is the soffit to be seen or exposed?

Casting Yard Operations • Plan Casting Yard operations for minimal breaks in production.

• If moulds are used allow for a significant bedding in period before production starts.

• The layout of the casting yard can be critical – plan early.

• Review cast identification requirements at an early stage as these may require metal to be added/taken off the moulds.

• Ensure that the concrete process has been stabilised is “in control” and the mix is accepted.

• Consider curing/striking times and storage requirements when designing plant.

• Consider lifting requirements in the design of the plant.

• Review cubemaking and testing requirements early.

Reference Documents: Concrete – Kier Technical Guidance Note TGN 5 – Concrete Advisory Service TGN 9 - Preparing, curing & Testing Cubes TGN 10 – Recording Concrete Cubes Correctly TGN 10 Form 2515a – Concrete Cube Results Analysis Example BS EN 206: Part 1:2004 Table A.13 Concrete Mix Designs BS 5328: Part 1:1997 Concrete Cube Testing Requirements BS 8110: Part 1:1997 Minimum Cover to Reinforcement

Page 52

Avoiding Defects - Revision D – July 2013

10.0

Screed – Cement / Sand

Check the specification and contract documents Preconstruction • Consider joints between heated and unheated areas.

• Where under floor heating is present look to combine the package to avoid issues of responsibility for joint, sequencing, etc.

• Look to minimize steps in the screed wherever possible.

• Ensure the MEPH designer’s heat loss / gain report is included in the order.

• Ensure sufficient falls to drains on details. e.g.walk in showers.

• Arrange for testing as per specification and if necessary arrange a review of the screed design by Sandberg or similar.

• When doing a wet room, do the whole room as fall to the gully where possible.

• Check who is specifying the gullies.

Construction • Check work area is adequately protected from wind, rain and cold weather. Water that has penetrated or is lying around insulation is impossible to remove.

• If bonded screed (25-40mm) is required, ensure that base is thoroughly prepared, cleaned and slurry coat applied at correct time.

• If unbonded screed (min 50mm, not nominal) is required, ensure base is flat and dpm/separating layer is properly laid.

• Where site mixed screed is used the cement / sand is to be gauged (bucket /box) and mixed in a forced action mixer.

• Carry out a level check to ensure minimum thickness.

• If screed is thicker than 50mm it should be laid in 2 layers.

• When laying two layers the top layer should be laid and hand compacted as soon as possible after scarifying the bottom layer.

• Screed to be compacted by roller / hand rammer.

• Mesh should be laid in centre of screed.

• Chicken wire serves no purpose.

Avoiding Defects - Revision D – July 2013

Page 53

• Mesh should be used in heated screeds, floating screeds, and in unbonded screeds which receive rigid finishes.

• Screed to be cured by laying polythene ( Fire Retardant LPS 1207) on surface and trapping it down at edges. Minimum 7 days for bonded and 24 days for unbonded or follow supplier’s recommendations.

• Protect from the effects of cold weather.

• Ensure any previous day’s screed cleaned back to sound vertical day joint.

• New screed must be protected from traffic for a minimum of 7 days.

• Consider use of rapid hardening screed to enable foot traffic at earliest opportunity.

• Be aware that all screeds crack.

• Construction joints in concrete will show through screed.

• Whilst current thinking is to screed as large bays as possible, consideration must be given to the applied finish, and joint positions adjusted to suit. Plan the joint positions.

• Cracks are caused particularly by sudden change in section, especially at corners.

• Ensure movement joints are continued through screeds and floor finish.

Granolithic • Ensure bay sizes and grano thickness is controlled.

• Thickness 20-40mm with bay sizes 25-15mm respectively for bonded construction.

• Base concrete must be fully prepared and aggregate exposed. following confirmation of agreement by structural engineer.

• Ensure the concrete is thoroughly pre-wetted before laying grano.

• Curing must be a minimum of 7 days with close fitting polythene.

• Ensure movement joints are continued through screeds and floor finish.

• Consider joints between heated and unheated areas.

Page 54

Avoiding Defects - Revision D – July 2013

Under Floor Heating • Seek specialist advice underfloor heating.

to

programme

commissioning

of

• Avoid “cooking” the screed by limiting daily temperature rise.

• Is temporary heating required?

Reference documents: Kier Technical Guide – Floor Screeds TGN 4 – Quality of Floor Screeds TGN 4 - BRE Drop Hammer Test Readings Quality of Floor Screeds Attachment BS 8204: Part 1 - Screeds, Bases & In-situ Floorings – Concrete Bases & Cementitious Screed to Receive Floorings BS 8204: Part 3 - Screeds, Bases & In-situ Floorings – Polymer Modified Levelling & Wearing Screeds

Avoiding Defects - Revision D – July 2013

Page 55

11.0

Screed – Flowing (Pumped)

Check the specification and contract documents.

Preconstruction • Check compatibility of levelling adhesives – are primers required?

compounds

and

flooring

• Ensure movement joints are continued through screed and floor finish.

• Consider joints between heated and unheated areas.

• Plan for a SLOW Drying time.

• To be efficient BIG areas need to be available daily.

• Ensure minimum thickness over underfloor heating pipes or conduits has been achieved in accordance with the relevant BS. Construction • Check weather conditions will not affect construction.

• Check base levels to ensure minimum thickness.

• Ensure separating membrane is intact – these screeds are gypsum based and the sulphates can adversely react with cementitious materials.

• Beware of delays between loads – wet edges that are starting to go off can cause ‘flash’ setting of the new material with expansion and possible disruption of joint.

• Consider using temporary vertical stop ends.

• If insulation is specified, ensure it is continuous and the correct type.

• Ensure perimeter soft joints are fully stuck to insulation and watertight.

• This type of screed degrades and soften with water. This effect should reverse when the screed dries out.

• These types of screed can be difficult to assess for subsequent finishes as moisture content varies.

• Consider shape of pours, long pours can crack.

Reference documents: Page 56

Avoiding Defects - Revision D – July 2013

Kier Technical Guide – Floor Screeds TGN 4 – Quality of Floor Screeds TGN 4 - BRE Drop Hammer Test Readings - Quality of Floor Screeds Attachment BS 8204: Part 7 - Screeds, Bases & In-situ Floorings – Pumpable Self-smoothing Screeds

Avoiding Defects - Revision D – July 2013

Page 57

12.0

Temporary Works/Scaffolding

Check the specification and contract documents Preconstruction • Comply with Kier Temporary Works procedures.

• Determine whether traditional tube and fitting scaffold, a system scaffold, cherry pickers, scissor lifts or mast climbers are the best access options.

• Hire periods to commence only when scaffold is first available for use after erection and shall terminate on the date on which instructions are given to dismantle.

• Agree maximum period for scaffold strike to be undertaken following notification from Kier. Inform scaffold company that costs will be contra-charged to them past this date.

• Extra hire rates to be pro rata to the amount of scaffolding standing on expiry of the minimum hire period. Agree buffer period for extended hire free of charge.

• Agree credit to be given if scaffolding off-hired earlier than quoted duration.

• What operations is the scaffold to be designed for?

• Which elevations require debris netting?

• How many lifts are required and at what centres?

• Establish board with of working platform.

• Establish number of lifts to be fully boarded at any one time.

• Consider proprietary systems such as Combisafe or KGuard for brick guards and/or double guardrails.

• Consider access to scaffold. Is this to be ladders, ladder towers (‘Haki’ stair towers) or passenger hoists?

• Are fans required to be erected to protect public?

• Ensure that public protection walkway have the first lift double boarded with a plastic membrane between the boards, standards are painted and all covers and protectors are in place i.e. threads on clips, plastic end caps.

• Consider who is responsible for lighting of scaffolding on public highway.

• A scaffold license is required from Local Authority before erection on or above public highway.

Page 58

Avoiding Defects - Revision D – July 2013

• An additional licence from the local authority is required for a protective fan.

• Obtain necessary temporary pavement or street closures and ensure provision of signs and diversions to keep public away from vicinity.

• If the scaffold is “weatherproofed” a temporary works design is required and the material used must be LPS 1207 flame retardant.

• Ensure galvanised tube is used to avoid rust staining to structure.

• Consider use of telescopic transoms.

• Plan edge protection to slabs, staircase handrails, roof edges.

• If work on roofs is fire escape provided?

• Is the supply of the hoist itself included in the hoist tower supply.

• What type of hoist is needed – goods, passenger, single or twin cage, gantry hoist. Check SWL required. Is it tied to structure?

Construction • Use only competent scaffolders (NASC qualified).

• Netting installation to be undertaken by FASET certified operatives only.

• Ensure a weekly inspection regime by a competent person, is in place.

• Ensure particular attention is paid to the foundations / soleplates • A handover certificate must be in place as well as the statutory register.

• Warning signs (“Not in Use” or similar) to be displayed when scaffold being erected / adapted or dismantled.

• Consider the loading platforms, are they to be erected progressively? What will they be used for? (Check size and strength) • Are gates to loading platform swing up design? These are strong but light enough to be operated safely.

• A sign advising safe working load is to be fitted to the front of the platform gate.

Avoiding Defects - Revision D – July 2013

Page 59

• Is there access for a forklift truck to the access platform?

Pedestrian barriers required to cordon-off area below loading platform. KC Eng standard design to be used.

• Consider the progressive erection progressive strip and adaption.

and,

if

necessary,

• Ladders are to be made inaccessible when site is closed.

• Changes to scaffolding are to only be carried out as approved by competent designers/ scaffold suppliers.

Reference documents: Kier Group SHEMS SG14 Scaffold Guidance Refer to the RED TOPS

Page 60

Avoiding Defects - Revision D – July 2013

13.0

Structural Steelwork

N.B. All metal decking acting as temporary formwork is temporary works and must comply with the Kier Temporary Works procedure.

Check the specification and contract document Pre-construction • Edge protection should be designed in. (RED TOP) • Hold design co-ordination meetings walling/cladding & other interface trades.

with

curtain

• Who will do purlins / cladding / rails / windposts?

• Has all secondary steel for cladding, masonry support etc been bought?

• Are rolling tolerances compatible with finished requirements?

• Should the primaries/secondaries be precambered to allow for deflection when concreting?

• Steelwork designed to be composite may need propping.

• Who is responsible for design and specification of connections?

• Are HSFG (High Strength Friction Grip) bolts required?

• Has the size and grade of holding down bolt been checked?

• Who supplies the holding down bolts?

• Is the holding down bolting adequately detailed to allow installation? Or are they post drilled.

• Is temporary bracing required and who is designing it? Who is responsible for temporary stability?

• Steel frames have collapsed during erection so ensure that the proposal is understood. e.g. turfers through metal decking.

• Does the installation sequence allow for the temporary bracing to be effective?

• Have measures been adopted to restrict temporary deflection and rotation?

• Connection surface must be unpainted where decking is to be studwelded.

• Are full builders’ works details available before manufacture?

Avoiding Defects - Revision D – July 2013

Page 61

• Is the paint to specification and compatible with finishes or will steel be supplied unpainted. (Think about protection or touch up).

• Can we benefit from any group agreements?

• Where possible ensure all trimming steel has been considered and is in place prior to cutting holes though deck.

• Avoid retrofit at height.

• Ensure edge protection (e.g. easi-edge) caters for phased handovers as well as final case.

Pre Erection • Ensure ground conditions are suitable for the craneage / cherry pickers used. Comply with Kier Craneage procedures.

• Ensure erection method statement details measures to prevent damage to coatings, especially during handling.

• The method of making good any paint damage needs to be considered especially where access is difficult.

• Has a method statement been prepared for grouting base plates?

• Has the grout material been specified for base plates?

• Ensure bolt holes are cleaned out or brushed out for resin, including any hole formers, and the base concrete has been sufficiently pre-wetted.

• Are nets being used? If so have they been properly inspected by a competent / trained person? Has a check certificate been obtained?

• Have net fixing points been designed in?

• Ensure holding down bolts are moved after striking template, when concrete has hardened sufficiently the next morning, to free them.

• It is good practice to put Denso tape on the bolt head to protect threads.

• Where possible site measure components fitted directly to the steel frame due to the large tolerances.

• Survey positions / height of holding down bolts and level of concrete within 48 hours.

• Is the top of foundation suitable (level, reasonably smooth) before erection?

Page 62

Avoiding Defects - Revision D – July 2013

• Is the steel from an approved source and CE marked?

• Ensure origin and quality of steel is acceptable, especially if imported. (Keep records.)

• Are lifting beams required?

• A surveillance visit to the suppliers works by a competent person is mandatory. (See Divisional standard –Procurement of Steelworks) • Are all tolerances compatible – lift shafts, secondary steelwork, cladding, false ceilings etc?

• Agree checking regime for bolts in frame (including size and grade) and ensure compliance. (Torque settings).

• There should be no site welding unless approved by consultant / designer.

• Site welders must be properly coded.

• Ensure welding rods suit grade and finish of steelwork.

• Is preheating monitored?

required–if

so,

how

will

temperature

be

• Check and comply with testing requirements.

• Burning of holes is not allowed.

• On site welding may need a 415V 3 Phase electrical supply.

Construction • It is good practice to grease the threads when replacing nuts.

• Ensure sub-contractor has checked the frame for level and plumb before final check by Kier.(Do not do work that we have paid someone else to do!)

• Ensure lightning protection is continuous from foundation to steel (if required).

Reference documents: NSSS National Structural Steelwork Specification -Section 8 – Erection tolerance, Section 9 Workmanship BS/EN 10034 Steel Fabrication Tolerances UB & UC BS/EN 10056-2 RSE Steel Fabrication Tolerances BS/EN 10210-2 Hot Finished RHS SHS & CHS Sections Avoiding Defects - Revision D – July 2013

Page 63

BS/EN/ISO 12944: Part 2 & ISO 9223 Steelwork Durability Exposure Conditions to Corrosive Environments

Page 64

Avoiding Defects - Revision D – July 2013

14.0

Metal Decking

Check the specification and contract documents Consider and plan temporary works requirements Pre-construction • Check the specification and structural engineer’s information is adequate for sub-contractor.

• Check span of metal decking against manufacturers literature for allowable deflection.

• Ensure gauge of decking is specified or confirmed as subcontractor design with approval.

• Check that all vertical shuttering requirements to the decking are contained within the design and scope of works.

• Consider and plan temporary works requirements with site temporary works co-ordinator/ sub-contractor and obtain approval from the structural engineer and Kier Engineering services.

• Check all electrical requirements for stud welding and access restrictions are contained within the sub-contractor package.

• Check testing regime for studs is included in scope of works.

• Is the contractor required to provide a grout tight deck? If not, ensure that the concrete contractor is required to clean the works beneath the deck.

• Ensure design is in place for protection of builders work openings and that the design has been approved by KC Eng. • Ensure that all design openings have been included on the drawings and that the locations have been approved by all design teams.

• Ensure sheeting is programmed to be lifted into position as frame is constructed or within the frame package.

• Consider sequence of loading out packs to facilitate the erection sequence and has structural engineer agreed loading positions for the frame in the temporary condition.

• Check testing regime for studs is included in scope of works.

• Ensure beams are installed correctly without a paint finish on the top surface.

Avoiding Defects - Revision D – July 2013

Page 65

• If service penetrations are required through the slab they are likely to be large and require approval by structural engineer so consider these early.

• Consider use of lytag mixes to reduce load on metal deck from wet concrete.

• Consider how interface between edge trim and edge protection will be managed.

• Install edge protection to beams prior to metal decking start.

Construction • Are sequence drawings agreed and all drawings approved for installation before start?

• Have full installation method statement and risk assessments been signed off for the following: o Installation of edge protection. o Installation of netting. o Installation of access stairs. o Installation of decking and up stands. o Installation of temporary propping. o Installation of concrete floor and reinforcement.

•

Has edge protection/netting been provided? (see also section on Temporary Works)

•

When nets are used, ensure that the ties do not hapmer the deck installation by tying over beams – Use proprietary clips instead.

• Ensure deck suppliers issue drawing for sign off of temporary propping to decking or beams. Refer to Kier Temporary Works procedures and ensure competent person issues a permit to load prior to concrete being placed.

• Is the deflection of metal deck after concrete pour within design criteria? If not propping will be required.

• Where slabs are being cast to depth not level, consider whether the end product will be within specification and whether sufficient allowances have been made for floor finishing / leveling works.

•

Page 66

Safety nets must be removed prior to stud welding. Any cutting with grinders must not take place near netting.

Avoiding Defects - Revision D – July 2013

•

Consider means of access and logistics plan with regard to preloading of mesh.

• Understand and agree any elements that need to be left out or removed to allow other trades to complete their works e.g. installation of plant, planks etc.

• Has the design of temporary construction joints been agreed with the structural engineer to accommodate sections being cast at a later date.

•

Are edge trim details as specified tie-backs in position and the correct size and spacing, formed holes, overhangs correct size and location etc.

• Consider risk of fire during stud welding operations.

• Protect finished surfaces below (i.e. cladding, glass) prior to stud welding and concreting operations.

• It is usual to have a test requirement for stud welds. Confrim this with structural engineer.

• Consider the profile of the deck. Does this reduce/increase the required amount of Concrete?

• Consider requirements for upstands, is the heights of upstand achievable.

• Are tolerance requirements for slab edges achievable?

• Ensure that the edge trims are installed prior to stud welding operations.

• Consider halfen support for cladding at slb edges where this may clash with rebar/ studs.

• The thin concrete slabs used are especially vulnerable to cold weather – Take necessary precautions (YELLOW TOP) Reference documents: Concrete – Kier Technical Guidance Note TGN 5 – Concrete Advisory Service TGN 9 - Preparing, curing & Testing Cubes TGN 10 – Recording Concrete Cubes Correctly TGN 10 Form 2515a – Concrete Cube Results Analysis Example BS/EN 206: Part 1:2004 - Table A.13 Concrete Mix Designs BS 5328: Part 1:1997 - Concrete Cube Testing Requirements BS 8110: Part 1:1997 – Minimum Cover to Reinforcement Avoiding Defects - Revision D – July 2013

Page 67

15.0

Fire Protection

Check the specification and contract documents Pre-construction • Are the fire requirements properly specified and understood?

• Ensure labelling is bought & installed.

• Ensure any fire resistant spray is compatible with the steelwork finish and that the applied finish is suitable for the section of steelwork.

• If the finish is exposed is it acceptable?

• Can intumescent paint be applied to the existing finish on the steelwork? Is it compatible? Is a sealer required? (What protection is required prior to application?).

• Has fire stopping been detailed between cladding and frame?

Probably required at 20m vertical intervals.

• Has fire stopping been detailed within large areas of raised flooring or suspended ceilings? Probably required at 20m intervals.

• Consider Manufacturer guarantees.

inspections

and

insurance

backed

• Who is responsible for fire stopping? (M&E) o From opening to service sleeve o Within service cleeve/cable tray • Are fire dampers provided if required? Are they accessible for maintenance purposes and supported correctly?

• Has the use of contractors accredited considered for thickness testing?

by

FIRAS

been

• Manufacturers details should be sought with regard to certain fire stopping installations, such as the passage of plastic pipes, ducts (the incorporation of dampers where necessary) and services insulated with non-fire rated insulation.

• Identify requirements for the masking of adjacent surfaces from overspray drift early.

• Ensure that if intumescent cladding is to be applied to steelwork that sufficient space is allowed for the intumescent paint to thicken and provide the required protection. Or (alternatively) consider using the cladding as the fire Page 68

Avoiding Defects - Revision D – July 2013

protection and omit the paint – this will require approval of the structural engineer (and possibly others).

Construction • If a spray on fire protection is required to ceilings ensure all necessary fixings / drop rods have been installed for M and E services.

• Ensure ambient conditions, especially surface temperature of steel, are suitable for application of intumescent paint.

• Aim to use water based (rather than solvent based) intumescent spray. Solvent based intumescent sprays, if required, should only be used in controlled environments.(COSHH).

• Ensure thickness of intumescent paint protection is checked and recorded before application of top coat. Agree at which locations it is to be tested and check, approve and record wet / dry film thickness.

• Check that the width and depth of intumescent mastic gives the required protection. (Check & Record).

• Ensure that intumescent mastic is applied behind any masonry or other fixings. Beware of gaps in mastic.

• Check that any making good or joint filling to fire boards is acceptable. Joints between boards should be smoke tight.

• Can joints in the fire board be butted, or should they be staggered?

• Ensure that fire protection is continuous around service penetrations.

• Is the material being used as fire protection suitable?

• Check loading of structural fire stopping in risers.

• If holes are required in structural fire stopping ensure that integrity is checked before cutting out.

• Check any requirements for fire stops in cavities.

• Ensure that all adhesives used are compatible with the substrate.

• Is the correct fire certificate available for doors, including the door frames?

Avoiding Defects - Revision D – July 2013

Page 69

• Are vision panels fitted to fire doors the same size as tested?

If not, check with supplier and obtain a further assessment or test.

• Is the fire door marked correctly?

• Check that smoke and intumescent seals on doors have been fitted as required.

• Have all gaps around the door frames been properly sealed?

Is the material used suitable?

Reference documents: Building Regulations Resistance

Page 70

Approved

Document

Avoiding Defects - Revision D – July 2013

B

2007

-

Fire

16.0

Swimming Pools

Check the specification and contract documents Consider and plan temporary works requirements Refer to section on Reinforced Concrete for general advice.

Construction • Seek specialist technical advice early.

• Avoid excessive heat build-up during curing by using mix with moderate cement content.

• Follow concrete guidance (see concrete section of Target Zero Defects booklet).

• Carry our slump test just prior to placement and reject if not compliant.

• Ensure good compaction without excessive vibration which can cause laitance on surface.

• Protect from frost and drying effects of sun or wind.

• Ensure sufficient setting out points are available and sight lines are clear as these are critical to achieving tolerances required for compliance.

• Avoid adjustments such as jack hammering or additional render as these can compromise the water resistant structure.

• Ensure the amount of concrete cover is well controlled to avoid cracking.

• Consider cutting a slot and securing hydrophilic strips in place when preparing the day joint prior to pour. Agree this with designer in advance.

• Agree maximum pour sizes to avoid excessive expansion / shrinkage.

• Kickers should be poured ‘monolithic’ to prevent problematic corner joints.

• Create shape for box outs to suit proper compaction of concrete when fixture is cast in e.g. a box out in a wall should have a sloping soffit to ensure concrete can be properly compacted.

• Apply rough finish or proprietary primer to flanges to ensure good seal.

Avoiding Defects - Revision D – July 2013

Page 71

• Ensure waterproof concrete is continuous up to and beyond splash zone and around channel and grating.

• U-value of basin (floor & walls) must not be less than 0.25 W/m² as calculated according to BS EN ISO 13370 • Check leak test requirements for basin.

• Swimming pools are highly corrosive environments, check anti-corrosion requirements and properties of all fixtures and fitting.

• Review lighting levels for risk of glare.

• Check ventilation requirements and ensure adequate for comfort and efficiency.

• Check slip resistance requirements of tiling.

• Ensure tiles are fully ‘back buttered’ and correct comb is used for adhesive on render.

• Joinery must be resistant to high humidity levels.

• Pay special attention to cut outs and screw holes to avoid moisture getting into door core.

• Check acoustic requirements including reverberation times.

Page 72

Avoiding Defects - Revision D – July 2013

17.0

Grouting / Drypack

Check the specification and contract documents Pre-construction • Ensure design allows for air holes.

• Is there a requirement for cubes?

• Who is responsible Groundworker, Kier).

for

the

grouting?

(Steel

Erector,

• Can the base plate be designed with a hole for pouring grout?

The shutter will then be tight to the base plate on all sides.

• Allow enough time for grout to go off before applying additional load ie, concreting slab.

Construction • Before grouting has the steelwork frame been lined, levelled and approved?

• If a grout hole is not possible, grout base plates by shuttering tight along the 2 longer sides and then grouting from one end only. Ensure base is pre wetted.

• Check that the grout/dry pack has not date expired before use.

• Mix all types of grouts mechanically following the supplier’s recommendations.

• Do not exceed the water content recommended by the manufacturer.

• Is there a minimum dimension under the base plate?

• Drypack generally needs to be rammed into place to achieve the required strength as per supplier’s instructions.

• Ensure that any base concrete is at least 48 (preferably 72) hours old before drypacking above (Underpinning, etc).

• If temporary jacks are used to support structure, agree strength of drypack required before releasing the jacks, or consider an epoxy grout.

• Ensure a methodology is in place for drypacking against a soffit especially if it is at height.

Avoiding Defects - Revision D – July 2013

Page 73

Post Construction • Record when each location has been completed.

Page 74

Avoiding Defects - Revision D – July 2013

18.0

Brickwork / Masonry/Breather Membrane

Check the specification and contract documents Consider and plan temporary works requirements Preconstruction • Beware if detail design shows flashings in same joint as DPC Seek advice and a designed solution.

• Make sure sample panel is representative of the standard of intended work. Whenever possible the panel should be constructed by a bricklayer to the intended minimum acceptable standard. This should be recorded and signed off with copy included in the QA file.

• Where Type 2 breather membranes are specified eg Sisalkraft 40, check against construction sequencing. Type 2 membranes are more susceptible to tearing when left exposed to the elements and are to only be installed immediately prior to external cladding installation. In cases where external finishes or cladding will take longer, consider the use of a Type 1 membrane eg Tyvek Housewrap • Ensure that on-site silos are safely erected and used. (RED TOP) • Consider responsibility for brickwork support and windposts and that lead time for this is understood.

• Establish maximum height of lift per day (normally 1.5m) but beware effects of wind on new work and take precautions against collapse (check spec and consider implications of retarded mortar).

• Has spacing of movement joints been approved and checked?

• Wind loading of internal walls must be allowed for if being built prior to completion of external envelope.

• Consider cleaning regime thoroughly especially with regard to chemical damage to all surfaces Construction • Logistics - refer to Telehandler / Silos / Scaffolding / Loading Bays (RED TOP) • Ensure that on site mixing equipment has been approved and in suitable location.

• Ensure blockwork is kept dry before and during construction.

Avoiding Defects - Revision D – July 2013

Page 75

• New brickwork must be protected from rain and frost to avoid lime staining and/or mortar strength loss.

• Ensure procedures for hot and cold weather working are detailed and agreed.

• Ensure loading bays are large enough to mix bricks/blocks from several pallets (RED TOP).

• If mortar is mixed on site the sand and cement must be gauged (bucket/box) • Take mortar cubes as per specification • Ensure mortar mixes are suitable for the specified brick/block and required durability.

• Mortar strength should generally be less than brick / block strength.

• Mortar must be of a uniform colour and consistency with all materials coming from the same source – variations in colour and texture are NOT acceptable.

• Check bricks and blocks are to specification including colour (blocks are normally colour coded).

• Check dense concrete block 140mm and above, due to Health and Safety restrictions, on weight of blocks.

• Always keep blocks dry as wet blocks are heavier.

• Has the work been detailed to ‘brick’ size?

• What measures are required to ensure the temporary stability of the wall during construction? Use temporary propping if required.

• Cast in brickwork supports if possible.

• New masonry may overload lintels, Do they need temporary propping?

• Check that lintels are installed correct way up (if applicable).

• Consider mechanical hoisting for lintels.

• If catnic type lintels are specified which also act as drip trays, ensure proprietary stop ends are used.

• Ensure padstones have been properly specified by designer.

• Review all builders work requirements.

• Are dummy frames required? There is a cost but it is cheaper than rectifying inaccurate brickwork.

Page 76

Avoiding Defects - Revision D – July 2013

• On large openings torque steel wires around opening.

• Consider who is going to be responsible for DPM/waterproofing below ground to allow backfilling at earliest opportunity • DPC/Tray to be correctly fixed/jointed (check required lap) Bitumen DPC with torched joint is best.

• Support must be provided to all DPC trays.

• DPC / Tray to be laid on full bed as per specification.

• Weep holes should be installed above trays according to specification.

• Gauge inner and outer skins correctly, use gauge rods / datums.

• For partial cavity fill, build inner leaf first, and leave out leaf below top of insulation (resistant clips).

• For full cavity fill, build outer leaf first, and fully flush all joints on inner face before fixing insulation. Leave inner Leaf below top of insulation.

• Ensure insulation is installed sufficiently below ground level to avoid condensation.

• All cavities and edge of insulation to be kept clean.

• Use battens or other system. It may be difficult but is critical.

• Where possible, always screw fix ties to steelwork but shot firing may be acceptable. Obtain ‘gun’ supplier’s advice and carry out tests and training.

• Ties must slope outwards and be level or sloping on the outside and be embedded a minimum of 50mm min.

• Ensure ties are installed the right way up.

• Check tie centres required for insulation.

• Ensure correct type of tie at movement joints.

• Ties at reveals / movement joint are at specified distances.

• Ensure type of tie is suitable for height of masonry.

• Check distance of ties required adjacent to stainless steel support angles.

• If stainless steel supports angles are not continuous ensure there is a vertical movement joint where it stops.

• HOLD POINT: check all support angles prior to loading.

Avoiding Defects - Revision D – July 2013

Page 77

• Ensure perps are fully filled.

• Leadwork trays are normally bedded by the bricklayer, but dressed by the plumber.

• Brickwork laid on a support must not overhang by more than one third.

• Beware of concrete tolerances or out of line masonry affecting support design.

• If a masonry joint must be ground or raked out, e.g.To allow a single ply membrane to be pointed into the joint, ensure care is taken not to damage the DPM. • It is better to ensure the bricklayer leaves a gap for membranes to be installed rather than raking out later.

• Note: To establish if drips are correctly located, assume internal face of external skin is always wet.

Specialist advice can be obtained from KC Eng. and Supply Chain.

•

Brick Suppliers (R Geddes/Hanson/Ibstock)

•

Catnic, IG Lintels, Birtley, Hendricks

Reference documents: BS 8103 Part 1 - Straps for Masonry BS 5628 Part 1 - 2005 Mortar Mixes for Masonry BS 5268 Part 3 - Durability & Fire Resistance Guidance BS 8000 Part 3 – Workmanship on Building Sites BS 5977 - Lintel Design – Load Assessment S 6178 Supreme Concrete Lintels (2008) - Lintel Design Table

Page 78

Avoiding Defects - Revision D – July 2013

19.0

Roofing

Check the specification and contract documents Consider and plan installation access requirements Rooflights • Check requirement for structural support steelwork.

• Ensure support steelwork is designed to falls should this be required.

• Ensure necessary free area for ventilation is achieved.

• Review interface with air seal line.

• Review requirement for integral upstands versus framed upstands.

• Discuss type of actuators and opening capabilities.

• Consider cabling and wireway requirements for actuators.

• Agree trade work split between Electrical and Rooflight subcontractor.

• Discuss method of operation (manual/automatic).

• Consider permanent access strategy. Is there a requirement for fall protection to perimeter.

• Ensure fragility classification is requirements agreed – CWCT or ACR?

defined

and

testing

• Where possible fragility should be eliminated in accordance with CDM Regulations.

• Bespoke /Non-proprietary rooflights will require testing to determine their classification – ensure cost of testing is included.

• Ensure U-value performance is specified as an average weighted value for the entire rooflight assembly not just the glass.

• NB: Glass u-values figures are quoted for glass pane in the vertical plane. BRE 443 Convention for U-value calculation specifies correction factors for sloping glass where this is not included otherwise in a specific calculation.

Avoiding Defects - Revision D – July 2013

Page 79

• Ensure pitch of rooflight provides adequate drainage, will the glass self clean or is there a risk of staining due to water ponding?

• Ensure solar gain (G-values) are specified for rooflight glass.

• Are internal blinds required for glare control?

ETFE Roofs • As the roof is likely be installed long before the power-on date, consider providing temporary power supply to maintain the pressure in the cushions. This will also require the pump unit being installed relatively early and this may need to be moved around to accommodate later installation of roof finishes.

• Confirm location of pump unit on drawings.

• Consider temporary air hoses from pump to cushions and coordination of these with curtain walling. There may need temp fixing points as roof will go on before curtain walling is installed.

• Procure remote monitoring of the system during construction phase. If the cushions deflate (due to power outage) and there is high winds, the cushions are prone to damage.

• Ensure correct detailing of interface flashings with curtain walling to ETFE. This will require coordination between ETFE subcontractor and curtain walling subcontractor and should be placed with the most suitable.

• Consider access regime (including management of unauthorised access) onto roof at design stage. Confirm man safe and maintenance access requirements.

• Bird protection required on extrusions.

• Consider who supplies the gutters.

• Is a walk-in gutter with hand rail or mansafe suitable? This can remove the need for the separate access gantry.

• Purchase support steel in ETFE package to prevent tolerance issues.

• Consider if variable solar control system is required • How will materials be lifted to the roof? ETFE will come to site in ‘coffins’. These need to be craned into the vicinity of the roof and given a suitable storage area until installation is complete.

• Arrange for maintenance / cleaning access to underside of cushions Page 80

Avoiding Defects - Revision D – July 2013

Metal Panel Roofs • Ensure finish to underside is coordinated (if required).

• Ensure continuation of air seal line is fully addressed.

• Review acoustic performance criteria.

• Check any requirement for radiuses – substrate needs to be level to avoid the formation of hips/valleys.

• Ensure tapered radiuses are bought in main order if required.

Flat Roof – Asphalt / Single Ply Pre-construction • Plan to get water off the roof early. Install downpipes early or fit temporary downpipes.

• Check minimum fall requirement (including allowances) complies with British Standards.

tolerance

• Does base have suitable levels and flatness for finish. Get S/C approval before work starts.

• Are handrails detailed weathered?

on raised

upstands

that

can be

• Check upstands are a minimum of 150mm above finished level.

• Are there requirements for mansafe systems?

• IKO (supply chain company) produce collars/shrouds ‘to order’ dependant on type of penetration – one offs are available.

Construction • Carry out a thorough inspection with S/C and get their approval before roof covering is overlaid.

• Ensure gullies have a flange compatible with the finish to ensure seal.

• Check parapet details (dpc/tray / flashing / coping) are installed correctly.

• Ensure any vapour barriers are correctly and completely installed, with all joints sealed. Pay particular attention around penetrations and install as shown on drawings.

• Establish system for working on roof as early as possible to protect the finished roof from following trades.

• Check detailing for lightning protection if required.

Avoiding Defects - Revision D – July 2013

Page 81

• Water ingress into a built up roofing system must be avoided as it can lead to thermal and structural integrity being compromised. Ensure that day joints and ensure night seals are installed in line with requirements of the system.

• If the seal has failed then the system will require lifting back until the affected area has been removed and replacing with new materials.

• Make sure fitting gangs working on price work fit an adequate night seal before ending works for the day.

• Ensure all insulation is covered whilst being stored outside before usage.

• Only allow fitting of glue down systems in dry weather.

• Once work has started the flat roof areas must be well managed by being kept well drained and pumped if needed (especially over weekends) as excess water will find the weakest point in the seals and soak into the roofing system.

Asphalt or Equivalent • If asphalt is laid on screed, it will generally need permavents to allow moisture that has been taken up by screed to dry.

• It is often better to lay concrete to falls and then asphalt after approx 7 days on top of felt.

• Ensure movement joints are detailed properly and then work to the detailed design.

• Ensure that asphalt is held against upstands using primer / expamet, depending on bond to substrate and is prevented from ‘rolling’ out of any rebates by sealing with a cement / sand fillet incorporating an SBR additive.

• The asphalt should lap with any DPC / tray above but use caution if cutting rebates in brickwork after laying. A better solution is to install DPC / tray one course above and use a counter flashing.

• It is possible that asphalt can suffer ‘thermal shock’ in cold weather.

• Ensure that specified solar reflective paint /chippings are applied in good time.

• Ensure that asphalt design reviews and installation inspections are by a ‘MAC’ (Mastic Asphalt Council) approved inspector.

Page 82

Avoiding Defects - Revision D – July 2013

Single Ply • Ensure that the method that the single ply material copes with upstands/internal angles is understood.

Ensure all requirements are strictly adhered to and that all joints are fully bonded together.

• Have walkways detailed on single ply roofs?

• Consider the use of ‘electronic’ testing of all single ply roofs.

Check specification for requirements.

• Ensure adequate controls and protection for access are in place. Even foot traffic can cause damage but a nail hole can cause a significant (but unfindable) leak.

• Ensure good housekeeping at all times.

• Avoid use in plant rooms or heavily trafficked areas.

• Is edge protection / netting required? If so training is required to issue Kier check certificate.

• Anchor points for netting need to be considered in the design.

• Pay close attention to protection of roof material if M&E installation to be carried out after single ply installation (swarf, screws, tools, damage etc).

• If a masonry joint needs to be ground or raked out to allow the single ply membrane to be pointed into the joint, take care around the DPC to prevent damage.

• Ensure that the gap for the membrane is left by the bricklayer rather than raking out later.

• Check construction of plant bases and feet of vibrating equipment e.g. chiller bases.

• There needs to be a minimum fall 1:80 at any point for single ply.

• Aim to install rain water pipe (temporary or permanent) at vapour membrane level then raise to finish level as roof is completed.

• Ensure when doing cut to fall that you consider the edge protection requirements.

• If the air seal line is in the decking butyl tape must be used.

Avoiding Defects - Revision D – July 2013

Page 83

20.0

Curtain Walling

Consider use of a façade consultant throughout the design, tender, appointment, sub-contractor, design, manufacture and installation process. At the time of writing we have worked well with Arup Façade Engineering.

Preconstruction • Is the glass proposed demonstrated to comply with the specification?

• Has overhead glazing been designed in accordance with CIRIA Guidance on glazing at Heights, (Guidance for sloping facades, glass roofs and canopies) and CWCT – Standard for slope glazing systems (Use of glass overhead) • Has the structural engineer identified the points on the building to which the cladding can be fixed, and defined maximum load values at those points.

• Are there likely to be movement or deflection issues.

• Will the design and installation allow for all building tolerances and have these been incorporated into the overall building design.

• Ensure that the fixings back to the structure are adequate and suitable.

• Ensure that builder’s work (mostly services and structural penetrations) is incorporated into design and manufacture to avoid on-site cutting and sealing.

• Review the design to check that there are at least 2 lines of defence against water ingress and that there are paths for water to escape.

• Ensure the architect has marked sections and plans with airtightness and insulation lines. (See section on airtightness) • If package includes rooflights, ensure specification includes the phrase ‘non-fragile as defined by CWCT guidance’ (currently TN66/67 and supporting TN92).

• Specify which rooflight class applies – Class 0, 1 or 2?

• Does anything warrant the CWCT testing suite i.e. is the façade certified? If there are any bespoke or specially-designed elements then testing may be required.

Page 84

Avoiding Defects - Revision D – July 2013

• Toughened glass should always have a kite-mark in a visible place unless special dispensation is given by Building Control.

• Have interfaces with alternative materials been designed clearly.

• Ensure thermal calculations are checked.

• Review if the glass is required to be toughened to ‘suit’ and comply with Building Regulations.

• Ensure that details specify precautions to prevent bimetallic corrosion.

• The interfaces must be designed and installed properly to prevent air leakage.

• Consider Part L audit and testing of air tightness and refer to Kier Group agreement with Wintech Engineering or Arup Façade Engineering.

• Agree with all parties’ location of all tests prior to commencing.

• Is on-site/off-site weather testing available / required?

• Has independent off-site testing of finishes been specified?

• Metallic paint is impossible to touch up.

• Consider if parapet can be designed 1100m high to avoiding temporary handrails? Allowance needs to be made for tolerances – if FFL is high by 20mm then parapet will be less than 1100mm • Think about structural movement joints and how these are reflected in the façade.

• Make sure everyone understands which face of glass is which.

Face 1 is the outer face of the outer panel i.e. the face the sun’s light hits first.

• Consider thermal shock – do bulkheads have to be vented to prevent heat build-up. Are there constraints placed on blind or curtain colour and gaps.

• Beware structural steelwork and curtain walling do not have comparable construction tolerances and deflections.

• Contact the procurement team for Standard Scopes and Supply Chain members.

• Manifestation will be required at GF level unless there is a mid rail.

Avoiding Defects - Revision D – July 2013

Page 85

• Consider a CP clarification that only standard spot manifestation transfers are allowed for, otherwise they become subject to debate.

• Do any internal partitions meet the curtain walling? Consider deflection, acoustics at the interface.

• Is fire stopping required at floor level?

• Has toughened glass been heat-soaked.

• Should laminated glass be detailed in critical locations instead?

• Understand tolerances fixing/backgrounds.

for

both

the

system

and

• Agree QCAS hold points and inspection prior to start on site.

• Water testing is recommended even when not specified.

• Review factory test requirements early.

• Has glass replacement strategy been designed in accordance with the building layout?

• Has access been designed maintenance regime.

to

allow

the

cleaning

and

• Ensure water proof details at the head of all openings are coordinated and detailed with both the structure and cladding systems.

• Do samples require testing under BRE conditions.

• Can panels be modified on site or do they require a return to the manufacturer.

• Fully understand how damaged materials are to be replaced once the system has been installed.

• Hold points may be required to sign off specific areas as installed.

• Has the design clearly demonstrated that all “cold bridging” has been eliminated?

• Ensure that the provider of secondary steelwork is identified.

• Ensure that the structural movement and tolerance report/constraints are included in the subcontractor/designer’s order.

• Ensure that the thermal performance subcontractor/designer’s order.

Page 86

Avoiding Defects - Revision D – July 2013

report

is

in

the

• Ensure that the acoustic performance subcontractor/designer’s order.

• Ensure that the Part L subcontractor/designer’s order.

report

constraints

are

is

in in

the the

• Be clear which requirement takes precedence in the event of a discrepancy e.g. structural vs architectural, architectural spec vs acoustic spec.

• Where appropriate, use a façade consultant to write the curtain walling/cladding/envelope specification.

Construction • Check whether the slab has to be loaded, de-propped etc before installing brackets and cladding.

• Can cladding be installed by crane from floor above rather than top floor (if crane required). This is less likely to be winded off.

• Ensure adequate and clean storage facilities are available for all materials.

• Has the building been surveyed prior to the works starting on site and undertaken early enough for the design team and subcontractor to incorporate the findings into the final design.

• Has the method statement highlighted the specific requirements for lifting of all the materials, specifically for such items as glass, large panels , stillage’s and stick systems.

• Have all system fixings been designed and approved for connection to the main structural members and inspection hold point agreed.

• Be aware of temperature, moisture and all other technical data for the application of bonding and sealing.

• Ensure that the sub-contractor and Kier team fully understand the cutting and fitting requirements for the system’s gaskets ( shrinkage and pressure plate application).

• Verify that all of the sub-contractors installation team are approved installers of the materials being used.

• Understand the cutting regime for the materials and what remedial have to be carried out to protect exposed edges.

• Establish what the requirement from both the client and manufacturer is for testing the completed works i.e. air test, water test.

Avoiding Defects - Revision D – July 2013

Page 87

• Has the method statement covered the installation of the system materials in the temporary condition for such items as wind loading, stacking, and minimum number of fixings to be applied if working area has not been completed during each working shift.

• Identify permanent access systems to roof areas and ensure closure details are complete.

• Has a ‘glass risk assessment’ been carried out?

• Use caution with labels stuck to glass and the use of low tack tap on extrusions as these may leave permanent marks.

• Remove all labels whilst access is available.

• Ensure drainage channels are completed to detail and not blocked.

• Check movement joints and slots are incorporated and not blocked by temporary packers and misplaced shims.

Unitised Glazing • Ensure unitised panel design calculations are compatible with the building structure, pay attention to loadings and expansion movement.

• Be aware that payment before delivery to site may be required as often manufacture will be well ahead of installation. If so ensure that the material is properly vested.

• Is off site weather testing of panels within the specification?

• Is on site hose testing to CWCT standards available/required?

• Is sufficient tolerance built in to panel brackets for interface with cast in channels?

• Check specification of bracket fixings.

• Establish responsibility for product interfaces.

• Check thermal insulation U values are appropriate.

• Check required noise (Db) levels are specified and the design and sub-contractors proposed systems are compliant.

• Carry out regular factory visits to check on quality and progress to avoid delays on site.

• Can all components be fitted to the panels prior to installation i.e. terracotta tiles, brise soliel?

• Check compliance of glass specification.

Page 88

Avoiding Defects - Revision D – July 2013

• Has independent off-site testing of finishes been specified • How will panels be delivered to site, offloaded and distributed.

• Consider utilizing just in time deliveries, unitised panels will take up a lot of floor space.

• How will the panels be installed, check weights and loadings of floor cranes.

• Ensure glass and panels are clean and label free prior to installation.

• Who is responsible for temporary protection to finished surfaces?

• Ensure operatives are leading edge trained.

• Have you been fully briefed by the supplier on the method of installation, QA procedure, inspection test plan, checks and hold points?

• Ensure labels are fitted on Teleflex.

• Ensure all gaskets are installed in the correct way around.

•

Are the spacers for the glass fitted all the way around and the correct size?

Reference documents: Centre for Windows & Cladding Technology Publications & Guidance BS/ EN 410 : Glass in Buildings – Determination of Luminous & Solar Characteristics of Glazing BS

14170

:

Glass

in

Building

–

Heat

Soaked

Thermally

Toughened Soda Lime Silicate Safety Glass

Avoiding Defects - Revision D – July 2013

Page 89

21.0

Cladding

Preconstruction • Ensure method for lifting / fixing of units, including weight, is allowed for in design.

• Is it clear who provides the secondary steelwork?

• Confirm that purlin / cladding rail centres and section sizes are compatible with the system being used.

• Ensure the design details submitted are complete, cleared and coordinated with adjacent trades and elements.

• Review tolerances for curtain walling for compatibility with those of the supporting frame.

• Ensure that tolerances between cladding and structural element are compatible and have robust air tight detailing – introduce hold point in QA sheet.

• Incorporate builder’s work (mostly services and structural penetrations) into design and manufacture to avoid on-site cutting and sealing.

• Ensure that architect has marked sections and plans with airtightness and insulation lines. (see section on airtightness) • Review the design to ensure that there are at least 2 lines of defence against water ingress and drainage paths for water to escape.

• If package includes rooflights, ensure specification includes the phrase ‘non-fragile as defined by CWCT guidance’ (currently TN66/67 and supporting TN92).

• Specify which rooflight class applies – Class 0, 1 or 2?

• Provision of any non-standard items –Testing criteria – how will the cladding tested interface with other trades, specifically structural steel - clearer angles – who supplies these and ensure that they fully detailed.

• Ensure water proof details at the head of all openings are coordinated and detailed with both the structure and cladding system.

• Do samples require testing under BRE conditions.

• Can panels be modified on site if necessary or is a return to the manufacturer required.

Page 90

Avoiding Defects - Revision D – July 2013

• Fully understand how damaged materials are to be replaced once the system has been installed.

• Hold points may be required to sign off specific areas as installed.

• Has the design clearly demonstrated that all “cold bridging” has been eliminated?

• Check the following against specification and CP’s; Air tightness, interstitial condensation, BREEAM rating, Bimetallic corrosion, fire wall conditions, fire boundary conditions, fixings, coatings (manufacturers’ guarantees).

• Consider responsibility for access. Consider suitability of base/round for plant – understand limitations.

• Suggest manufacturer/designer attends site at regular intervals and key stages during construction.

• Consider if parapet can be designed 1100m high to avoiding temporary handrails? Allowance needs to be made for tolerances – if FFL is high by 20mm then parapet will be less than 1100mm • Ensure thin sheets are designed out. 0.7mm should be used as a minimum to avoid fragile roof conditions.

• Think about structural movement joints and how these are reflected in the façade.

• Ensure the rainwater disposal system has been designed effectively.

• Has syphonic drainage been considered, if so will it need to be insulated due to the noise.

• Ensure provision of man safe system is included within the cladding package and installed as early as practicable.

• Access, safety nets and edge protection needs to be within subcontractor package.

• Ensure supporting structure is handed over before works commence.

• Ensure the roof structure is capable of supporting cladding packs before loading out.

• Ensure there are sufficient hold points during the process i.e. liner sheets are lapped and taped correctly.

• Design out site cutting of flashings.

Avoiding Defects - Revision D – July 2013

Page 91

• Ensure lightning protection system has been designed to coordinate with the cladding system and will the materials used for the cladding allow for bonding of the materials and conductivity.

• Ensure that the design for the builders work openings have been co-ordinated with the setting out of the cladding components.

• Ensure that the structural movement and tolerance report/constraints are included in the subcontractor/designer’s order.

• Ensure that the thermal performance subcontractor/designer’s order.

report

is

in

the

• Ensure that the acoustic performance subcontractor/designer’s order.

report

is

in

the

• Ensure that the Part L subcontractor/designer’s order.

constraints

are

in

the

• Be clear which takes precedence in the event of a discrepancy e.g. structural vs architectural, architectural spec vs acoustic spec.

• Where appropriate, get a façade consultant to write the curtain walling/cladding/envelope specification.

Construction • Install permanent rainwater system as soon as practical.

• Check whether the slab has to be loaded, de-propped etc before installing brackets and cladding.

• Can cladding be installed by crane from floor above rather than top floor (if crane required) in order to reduce being winded off.

• Ensure adequate and clean storage facilities are available for all materials.

• Has the building been surveyed prior to the works starting on site and undertaken early enough for the design team and subcontractor to incorporate the findings into the final design.

• Identify permanent access systems to roof areas and ensure closure details are complete.

• Have you been fully briefed by the supplier on the method of installation, QA procedure, inspection test plan, checks and hold points?

Page 92

Avoiding Defects - Revision D – July 2013

• Has the method statement highlighted the specific requirements for lifting of all the materials, specifically for such items as glass, large panels , stillage’s and stick systems.

• Has the project been given a copy of the installation guide?

• Arrange manufacturers ‘teach in’ briefings for installation.

• Ensure that the tolerances are correct in structural openings when fitting doors, windows etc.

• Ensure all cladding fixings have been designed and approved for connection to the main structural members and relevant hold point agreed for inspection.

• Be aware of temperature, moisture and all other technical data for successful bonding and sealing.

• Verify that all of the sub-contractors installation team are approved installers of the materials being used.

• Has the method statement covered the installation of the cladding materials in the temporary condition for such items as wind loading, stacking, and minimum number of fixings to be applied if working area has not been completed during each working shift.

• Consider what temporary protection is installation for weather if area incomplete.

required

during

• Ensure everyone is fully conversant with the cutting regime for the materials and remedials required to protect exposed edges.

• What is the requirement from both the client and manufacturer for testing the completed works i.e. air test, water test.

• Do the fixings need to be tightened to a torque? If so it must be specified the installers must use calibrated torque indicating tools and should appear as a hold point in the QA form.

• If fixings require a torque setting, checks must be carried out at an agreed frequency, and within the guidelines of the manufacturers recommendations.

• Ensure finished work is suitably protected including cills.

Reference documents: Centre for Windows & Cladding Technology Publications & Guidance BS 8298 : Code of Practice for Design & Installation of Natural Stone Cladding & Lining - Part 4 Rainscreen & Stone on Metal Avoiding Defects - Revision D – July 2013

Page 93

22.0

Air Permeability

Pre-construction: • Establish the airtightness criteria. Is there a contractual obligation or does a BREEAM or other rating automatically infer an airtightness value?

• Ensure that airtightness criteria are passed down into the appropriate subcontract orders i.e. envelope (curtain walling, external soffits, windows, brickwork/blockwork, SFS).

• Ensure the architect produces a set of ‘line of airtightness’ drawings using building sections and plans.

• Architect should also produce a ‘line of insulation’ drawing which can be reviewed with the airtightness drawing.

• Appoint a façade consultant to advise on airtightness.

• At an appropriate point (i.e. once façade subcontractor is on board and/or details have been developed sufficiently), place order with testing-house (HRS) and get their consultant to review the plans, sections and details and compile a report.

This should be presented back to the design team and their recommendations adopted.

• When reviewing tenders or ER’s, be aware of specified products that have poor airtightness. These typically are sliding doors especially the frameless or slim frame variety – and roller shutters. Where possible clarify/derogate or factor this in. Take advice from the manufacturer, subcontractor or façade consultant where appropriate.

• Airtightness is most at risk at interfaces between trades – be clear at interfaces as to responsibilities.

• A common area for interface issues is where services pass through the envelope. Make sure that sealing of the penetration to the envelope is in one or both packages.

• Drawing details should be reviewed with particular attention paid to the interfaces. Ensure there are no gaps.

• Leakage occurs most at penetrations that are post-drilled.

Therefore where possible make sure the services and other penetrations are known in advance and detailed as part of the envelope drawings.

• Ensure that non-airtight rooms aren’t accidentally included.

These could be waste stores or vented plant rooms.

Page 94

Avoiding Defects - Revision D – July 2013

• Check each louvre in the envelope carefully – if they are not fully ducted/blanked off then the airtightness line might be along the internal walls and not external.

Construction • Ensure a robust quality plan is in place for all operations regarding the envelope.

• Create a specific hold point for all services penetrating the envelope to be checked prior to covering over.

• Special attention is required for installed sliding doors. Has the installation been signed off at the specific hold points.

• All installation processes must have approved installation method statements with quality inspection and hold points clearly identified.

• Check each louvre in the envelope carefully – if they are not fully ducted/blanked off then the airtightness line might be along the internal walls and not external.

• Ensure regular visits are undertaken by the consultant/ architect to inspect the envelope as it is installed; agree hold points for these inspections.

• Manage instructions for changes to the envelope and fully understand the implications for the airtightness.

• Identify all personnel responsible for undertaking the preparation works for the air test and ensure all understand exactly what is required for the test to be completed.

Avoiding Defects - Revision D – July 2013

Page 95

23.0

Cleaning Cradles / Maintenance Units

Pre-construction • Ensure BMU (building maintenance unit) design and height are considered by the architect and dealt with as part of the planning application, not exceeding planning height limitations.

• Full cradle design and track loads are needed early enough to allow engineers to design bases and tie in the roof slab.

• If BMU is to be used for completing construction works, ensure this requirement is adequately considered at procurement stage – equipment needs to be of robust design to ensure it is not worn out by pre- practical completion use.

• Consider buying a spare cradle if it is to be used extensively during construction.

• Ensure all manufacturer warranties commence from PC and not from when equipment is handed over.

• Ensure adequate space is allowed to track the BMU around the building without damage to cladding.

• Check whether works are subject to provisional sums.

• Review the access solution chosen with client’s maintainance department where possible • Include BMU design in the client’s tender documents where possible and ensure design is compatible with other elements of the access / maintenance strategy for the building.

• Ensure structural / aesthetic issues have been considered.

• Consider the loads at a bend in the BMU track and if the slab needs to be reinforced to resist these loads.

• Where a BMU track can be walked on consider implication on handrail heights. For example – a 300mm high BMU track next to a 1100mm high handrail means edge protection is reduced to 800mm requiring handrail re design.

• How will work at height issues be managed where cradle to be used over pedestrian area?

• Consider engaging a specialist consultant for advice and inspection.

• How will the cradle be tied to the structure? This is particularly important where there is a raking façade as the cradle will need to be pulled in by some mechanism.

Page 96

Avoiding Defects - Revision D – July 2013

•

Consider lightning protection requirements – components to be bonded into building lightning protection.

• Where cradles are used as part of façade replacement/repair strategy, ensure that design incorporates suitable load capacity for largest item to be replaced or alternative lifting strategy is in place, particularly for glass façade.

• Ensure design of cradle takes into account façade construction, particularly where cradle tracks are vertically in contact with façade, contact points are designed where cradle touches façade and any rollers or lashing points are also designed.

• Fail safe system has to be designed in.

• Load capacity and maximum wind speeds for safe usage must be clearly shown on the cradle together.

Construction • Consider power requirements for both construction and post PC stages.

• Has the cradle been fitted with its own power supply connected to the building, can this be safely used in construction? If not how will power be supplied?

• Ensure that all lifting items are checked, inspected and certified as lift plan.

• Ensure logistics and access are planned and adequate.

• Ensure lifting equipment is available and adequately protected for cradle to be lifted.

• Lift only using designed lifting points.

• Ensure that all track and physical connections have been checked and signed off prior to final positioning of maintenance unit.

• A Third party inspection will be required prior to first use and a certificate issued with manufacturer’s instructions.

• Ensure all operators are properly trained.

• The area under the cradle in operation must be clear of materials and debris and personnel excludedto be an exclusion zone in order to allow safe landing in an emergency.

• Ensure that operation and maintenance manuals and manufacturers special instructions are available with the cradle/machine.

Avoiding Defects - Revision D – July 2013

Page 97

• Consider communications between operator and ground.

• Ensure that access to and from cradle is adequate and safe at landing points.

• Ensure that protected storage and maintenance of harnesses is provided for operators.

Post Construction • Ensure all documentation is complete at handover including up to date inspection / maintenance records.

• Ensure special instructions for use incorporated in operation & maintenance manuals .

• Ensure Health & Safety file incorporates safe removal of BMU.

Page 98

Avoiding Defects - Revision D – July 2013

24.0

Plastering

Preconstruction • Check the provision and detailing of movement joints.

• Pay close attention to junctions between dissimilar materials. It may be necessary to provide back-to- back beads, or bridge the joint with expanded metal, or if a structural column, cover the column with building paper and expanded metal prior to plastering – (typical application in stairways at floor levels).

• Timber grounds should generally be 3-4mm less than finished plaster thickness to allow for packing.

• In addition to timber grounds will temporary door linings be required?

• Agree the location, extent and method of any dubbing out that may be required if the substrate is not within tolerance.

• Review lighting to ensure that it is adequate and correct if the paint to be applied is gloss or semi-gloss.

• Consider protection to joinery, curtain walling, windows etc.

• Consider the level of lighting required and its position to achieve the specified finish. It is also useful to consider the permanent type and position of lighting that the finished work will be subject to. Wall lighting, in particular down lighters, will require a higher quality of plaster finish than elsewhere.

• Consider polystyrene infill or conduit plugs for electrical boxes to avoid blocked conduits or plaster filled boxes.

• Is temporary heating required in some areas in order to maintain the manufacturers recommended drying conditions?

• Consider the use of spray plaster but note that at this time some types of plaster can’t be sprayed i.e. Durafinish.

Construction • Ensure that constant checks are made on the materials and workmanship.

• Regularly check that the required finish and accurancy is being achieved.

• Check specification for type, thickness etc.

• Check width and plumb of reveals and narrow features, also that the plaster is to the correct height and will not compromise the suspended ceiling junction.

Avoiding Defects - Revision D – July 2013

Page 99

• Is the substrate suitable for accuracy, cleanliness and key – do you need a primer?

• Before starting work ensure area is signed off and dry/ watertight.

• Conduit should be fixed as tight as possible to the background surface.

• The chase needs to be of sufficient depth to allow the full plaster depth to be achieved.

• Expanding metal should be fixed to cover the chase.

• Consider if you need to render the bottom of the partitions as you often have a bulge left over which will be leave the finish out of tolerance.

• Insert a hold point after the mist coat of paint has been applied for final snags to the walls before the finishing coats of paint are applied.

• Check that preceding trades have completed their work.

• Review the Architects specification and ensure that all relevant notes on installation are followed.

• Add key items to be checked from the architects specification to the inspection and test plan.

Reference documents: British Gypsum White Book

Page 100

Avoiding Defects - Revision D – July 2013

25.0

Plasterboard Partitions

Preconstruction • Consider door jambs and door weights – Is secondary steel or additional studs required?

• How will risers be built? Do they need to be shaft wall?

• Consider M&E pattress schedule for wall mounted equipment.

• It may be necessary to install a different type of board or an additional layer in areas of high services.

add

• Check weight of such items as radiators which can be very heavy.

• Are the partitions fire rated? If so chec fire stopping requirements, particularly to service penetrations around doorframes.

• Fire tape is to be used as a minimum above ceilings.

• Consider how waste board will be recycled?

• Have you used Kier Trading Agreements – British Gypsum for Manufacture & Encon for distribution? Contact British Gypsum & arrange visit.

• To obtain a manufacturer’s warranty you have to source 100% from their specification, even down to using the correct screws.

• Check ‘Best Practice’ e.g. British Gypsum door detail acoustic / fire pads.

• Understand the interface with building services that run parallel to dry lined walls for example in corridors. What is the order of installation? Will you need to board and T and J prior to service installation or will you need to board from one side?

• The sealing around services etc is not just restricted to fire walls. The acoustic performance of the wall also needs to be taken into consideration.

• Builders work needs to be properly formed by the partition contractor. Do not allow the M&E contractor to make their own openings.

• Service positions must be coordinated to ensure that they don’t prevent access to the tops of the walls and to ensure that they do not go through door legs for example.

Avoiding Defects - Revision D – July 2013

Page 101

• Ensure that you understand how partitions are meant to interface with each other so acoustic reductions between spaces are achieved.

• Ensure that openings are formed using the specified BG details for openings. These can accommodate openings up to 3600mm but it is generally recommended that any openings above 2400mm should use a hot rolled steel support or goal post arrangement.

• Review areas of tiling for requirements for moisture resistance boards and/or reduced stud centres • Ensure the building is watertight before partitions commence and that preceding trades are complete (i.e. windows fitted to allow reveals to be installed).

• Insert a hold point after the mist coat of paint has been applied for final snags to the walls before the finishing coats of paint are applied.

• If modular wiring is being considered, can walls be constructed full height with upper board left off to allow “fishing” installation of modular cables?

• Consider ply-lined/backed partitions in heavily serviced, wallmounted and cupboard areas to eliminate noggin design costs and increase flexibility for installation & future client needs.

• Co-ordinate services to create “letter-box” entry (within ‘H’ frames at door locations) rather than ad-hoc service entries.

• Check coordinated service drawings to ensure that services don’t run through metal channels that are supporting elements such as doors.

• If there are groups of services that are running through a partition there is a danger that many of the supporting studs will be removed and this will undermine the structural integrity of the system. In some cases the routes of service may need to be tweaked slightly to avoid partition studs.

• If utilising horizontal service modules in corridor ceilings, consider pre-installation of high-level corridor side boards in advance of service module installation – access/working space unlikely to be possible for post services board installation.

• Where plywood is required in the wall make up consider agreeing with the client and Architect the use of OSB.

Page 102

Avoiding Defects - Revision D – July 2013

• Agree the method of setting out before the Architect develops the package. Will the setting out be to the centre line of the partition or the face of the plasterboard?

• Is there a requirement for a deflection head detail? On concrete structures this is normally 15mm and on steelwork structures this can range from 25-50mm. The designer needs to confirm the size and direction of this deflection.

• Where using lead lined partitions i.e. x-ray rooms in hospitals ensure that the details are agreed with the Radiation Protection Advisor.

• Ensure that sockets between bedrooms are not set out back to back as this can have an impact on acoustic/fire performance of the partitions.

• If plywood is specified in the build-up consider independent Acoustic test as the spec/number of cover boards could possibly be reduced.

Construction • Ensure latest drawings are issued to sub-contractor for setting out and information.

• Check subcontractors setting out.

• Confirm, with manufacturer if there is a requirement to leave a 5mm gap at the bottom of the partition to avoid moisture from the slab penetrating the board.

• When fixing plasterboard ensure that you don’t over screw the fixings into the boards and tear the cover paper.

• Ensure contractor is aware of noggin requirements for fixing furniture, sanitary ware, handrails, radiators etc.

• Check specification for board type, thickness, stud size, finish and insulation requirements – ensure correct storage procedure.

• Make sure vertical studs are positioned clear to allow sufficient room for pipe lagging, where high level pipework passes through partitions.

• How is acoustic and fire performance maintained in Back Box Design? Are putty pads needed?

• Check all services are installed and signed off prior to closing off.

• Check finish of taping, jointing and filling.

Avoiding Defects - Revision D – July 2013

Page 103

• Check that numbers and centres of brackets and type fixings are correct.

• Check that centres of metal are correct.

• Check that centres of hangers are correct.

• Check that the correct type of boards are used with the correct face and stagger.

• Do not allow boards with damaged corners to be used.

• Ensure movement joints are in line with manufacturer’s recommendation.

• Apply acoustic mastic to all slip joints deflection heads.

• Ensure acoustic interfaces are inspected (HOLD POINT) – These are difficult to resolve afterwards.

• Has plasterboards encasements to beams in order to maintain the acoustic rating been considered in steel structures?

• Areas with insulation must be fully filled – no areas missed.

• Review requirements for insulation.

• Proprietary top coat / sealer coat should be applied before decorating.

• Remember to seal around services such as external lights and CCTV feeds where they penetrate plasterboards linings to the external leaf. Use the appropriate air-seal tape such as Siga Sicrall 60.

Reference documents: British Gypsum White Book

Page 104

Avoiding Defects - Revision D – July 2013

26.0

Floor Finishes

• Check the matwell requirement in the contract. Architects sometimes specify a mat system that scrapes off dirt and removes moisture when all that is needed is a mat that removes moisture. The cost difference is circa £165/m2 with the latter being the cheapest.

• Check the requirements for matwells. i.e is a recess required?

• Are spares required under the contract? Do not assume that they should always be provided.

• Ensure floor finish levels relate to lift thresholds and staircase top and bottom risers. Levels at door openings are also critical.

• Check movement joint details these may require stop ends.

• Is base suitable – level, flatness, moisture, movement joints and construction joints?

• Generally cement / sand screeds dry 1mm / day, in good drying conditions.

• A dense power floated finish will take longer to dry; additional preparation may be required to provide a key for the installation of DPM. • Floors that measure over 75% RH will require the installation of DPM before the floor finish.

• Anhydrite screeds require particular attention, normal cement based smoothing products are not compatible.

• Generally Anhydrite screeds can not have a DPM installed and must be allowed to dry.

• Consider using an epoxy DPM where the finish will seal the floor (vinyl / rubber).

• Generally carpet tiles or Hessian-backed carpet will allow vapour through without problem (loose laid or using a partial adhesive system).

• Ensure that a full coverage of the specified sand is added to the final coat of any DPM to provide a key for the levelling compound.

• Beware of using a moisture sensitive finish on screed on concrete on polythene / metal. What appears dry now may change over time

Avoiding Defects - Revision D – July 2013

Page 105

• Concrete bases should be 6 weeks old before laying rigid tiling, and cement / sand screeds 3 weeks old (or a DPM may be required).

• Joints in ceramic tiles should coincide with joints in screed / concrete. Also joints in screed/concrete should be designed considering tiles. Normally 5-10m max (max area 40m), but 8m max on heated screeds (3.5m max if over isolating membrane). Never exceed a 2:1 ratio for bays. Consider extra joints at doorways or other restraints.

• Hard finishes generally require soft joints at perimeters.

• Ensure that details prevent any water from underneath finishes e.g. from behind toilet panels.

reaching

• Vinyl requires a very smooth finish, only normally possible with smoothing compound.

• Spreading adhesive on screed can pick up sand particles causing bumps under the vinyl.

• Allow for levelling compound.

• Consider ‘safe’ robust protection to stairs – proprietary products are available.

• Ensure Movement joints are designed and detailed.

• Check the requirement for DPM under vinyl.

• Surface DPM above under floor heating is not recommended.

Application • Ensure joints in concrete and screed base still match joints in rigid tiles and other floor finishes – if not take action as movement and day joints will show through.

• Check the quality controls when laying semi dry beds (e.g. mix, mixing and slab preparation).

• Ensure under floor heating systems is fully commissioned prior to floor finish installation. (Particularly in screed to ensure maximum expansion & contraction of substrate & drying out).

• Ensure bedding or adhesive does not bridge movement joints.

• Ensure top of semi dry mix or backs of tiles are fully ‘grouted’ before bedding tiles (terrazzo / marble).

• Ensure a solid bedding for rigid tiles with adhesive.

• Ensure fire retardant protection is procured, installed maintained.

Page 106

Avoiding Defects - Revision D – July 2013

and

• Are partitions built in and furniture / kitchen units installed before or after floor finish?

• Ensure temperature and humidity are controlled and compliant with the supplier’s specification.

• Check manufacturer’s recommendations for timber / laminate flooring – This must be allowed to settle before laying.

• Is broadloom or tiles to be used?

• What spares are required?

• Check requirements for trims, nosings etc.

• Slip Resistance - Design MUST consider requirements for slip resistance in operation. Obtain supporting test documentation.

• Understand and include clear guidance on cleaning regime to maintain all elements of the specification.

• Understand and agree direction of vinyl.

• Resin floor finishes should not be applied to floors that have under floor heating until the system has been commissioned and the temperature raised in accordance with manufacturer’s instructions. This constraint can have a significant impact on programme sequencing.

Reference documents: BS 8204 Part 6 - Screeds, Bases & In-situ Floorings – Synthetic Resin Floorings BS 8204 Part 4 - Screeds, Bases & In-situ Floorings – Terrazzo Wearing Surfaces

Avoiding Defects - Revision D – July 2013

Page 107

27.0

Internal Render

Pre-construction • Ensure that design of background minimises or controls cracking.

• Allowing blockwork to get wet before or during construction increases cracking risk significantly.

• In-situ concrete backgrounds will require scabbing, spatterdash or similar to achieve necessary bond.

• Structural background should be at least 6 weeks old before rendering.

• Check background tolerances and ‘dumb out’ in layers.

• Create hold points on QA sheets at critical stages.

• Be aware of anti-graffiti paint / sealer and the possibility that gloss finish may highlight trowel marks – produce sample panel for approval.

Construction • Ensure building/area weather tight (Temp minimum 5°C to prevent frost damage.

• Render mix should be cement / sand / plasticiser or masonry cement / sand. Do not use lime based mixes.

• Render mix to be in the range 1:3 to 1:4 by volume, generally stronger on concrete, weaker on block and brick backgrounds (check spec).

• Ensure all site mixed render is gauged – bucket or box.

• Ensure any movement joints in background are reflected through the render and finish by utilising suitable beading mechanically fixed • Maximum thickness should be 13mm on weaker backgrounds, 20mm elsewhere.

• If 2 or more coat work is used, first and subsequent coats must be combed to form a key.

• The subsequent coats should either be weaker or of the same mix but thinner.

• Render should be finished with a wood float, accuracy of 3mm in 2m.

Page 108

Avoiding Defects - Revision D – July 2013

• Check render for cracking and debonding before commencing tiling. If found seek advice before proceeding.

• If render is properly bonded to background it can generally be applied in bay lengths to suit that background (brick 12m, block 6m) but this may be limited by the amount carried out in one day.

• Ensure render is protected from rapid drying in the first few days • It is essential to use grounds for accurate work.

28.0

External Render

Pre-construction • Ensure that design of background minimises or controls cracking.

• Allowing blockwork to get wet before or during construction creates a major risk of cracking.

• Plain floated or trowelled finishes can suffer crazing and uneven appearance, especially under shallow lighting. Where it is specified, do trial panels for approval. Better to use a textured finish e.g. scraped.

• In-situ concrete will require preparation, as for internal render.

• Do not allow day joints except at specified positions they will show through.

• Render of EML (expanded metal lath) needs joints at 5m.

• Ensure correct spacings and fixings for EML. • Diamonds on EML should slope inwards and downwards to support fresh render.

• Generally use 2 coat work for sheltered and moderate areas, 3 coats for exposed.

• External render on soffits need specially designed support systems.

• Understand specific requirements for maximum thickness per coat.

• Proprietary and insulated renders are special cases. Consult manufacturer’s recommendations. Arrange ‘teach ins’ by specialist to understand stages for team.

Avoiding Defects - Revision D – July 2013

Page 109

• Are movement expansion / compression joints required?

• Consider interfaces with other trades and work fronts.

• Ensure hold points are added to QA sheets at critical stages.

Construction • Ensure sand is as coarse as possible while still achieving the required finish.

• Cold or wet conditions are often not suitable to install render.

• Corner and stop beads should be fully bedded or mechanically fixed – do not allow dabs.

• All fixings, beads, EML should be stainless steel / PVC. • Minimum thickness of 2 coat work is 16mm, 3 coat – 20mm.

• Never exceed 25mm without tolerances of background).

mechanically

fixing

(note

• All site mixed render should be gauged – bucket or box.

• Ensure render does not bridge DPC’s or cover weep holes.

• Subsequent coats should be either weaker or of the same mix but thinner than those before to control stresses.

• General protection to avoid contamination of the work should be given.

• Ensure that a system is in place to minimise discolouration caused by water splash from the scaffold/working platform in wet weather conditions.

• Ensure several days between coats – do not allow only 1 day.

• Ensure render is protected by hessian / polythene against rapid drying by the wind or sun.

• Check that undercoats are combed before setting

Page 110

Avoiding Defects - Revision D – July 2013

29.0

Tiling – Floor & Wall

Preconstruction • Ensure background has dried out minimum of 4 weeks for plaster and 2 weeks for render, assuming reasonable drying conditions-s/c to inspect and approve. (Keep records) • Ensure background is suitable, no plaster in wet areas.

• There is less risk to tiles if plaster not used as a background.

• Establish if setting out of tiling is critical. If it is the team must set out all components (wall, render etc) very accurately.

• Ensure any plasterboard is moisture resistant.

• Consider using a sealer.

• Beware – Any plasterboard in a ‘wet’ area, which includes baths incorporating a shower, must be coated with waterproofing sealer before tiling to avoid long term softening of the plasterboard. Adhesive can then be cement based but reduces flexibility.

• Ply absorbs moisture and will move. Primers/sealers only slow down this process.

• If plasterboard is fixed over plywood ensure that any studwork is strong enough.

Also refer to manufacturer’s recommendation.

• Ply must be screwed not nailed.

• Does Specification call for mirrors to be fixed in or onto tiles?

• Consider the positioning of floor gullies and working to falls to avoid bonding.

• Consider positioning of electrical boxes to avoid switches half in and half out of wall tiling bonds.

• Beware that a lot of manufacturers have lengthy shut down periods. Ensure you know when these are and PLAN for them.

• Check the slip resistance requirements to ensure correct type specified.

• Check lead in time for delivery - China as a typical example can take up to 16 weeks.

• When it is time manufactured?

for

procurement

is

specified

tile

still

• Is client approval needed on tiles size/colour/extent?

Avoiding Defects - Revision D – July 2013

Page 111

• Understand what has been allowed for in cost plan.

• Establish with consultants expectations of tiling full room coverage/splash backs etc.

• Are tiles the most suitable option? i.e. hygiene rooms would a vinyl up the walls and welded at base be better?

• For splash back in cleaners stores/classrooms use pre-cut whiterock for quick installation?

• Ensure splash back allowed for around water coolers.

• If floor tiles are laid while high level M&E installation is still underway ensure adequate protection is allowed for.

• If floor boxes are to be set in tile floors ensure they are set out in line with tile setting out to avoid awkward cuts to tiles.

• Plan for operatives working quickly if they are just doing splash backs – have they got access to all rooms for a full run through building and at least a mist coat on walls?

• Consider the positioning of signage in relation to tiling.

• Be aware of sealant specification e.g. slate tiles –how long should it be left on for?

Construction • Movement joints in tiles to be at 3.5m centres and at internal corners through tile bedding and preferably background in new build.

• Additional joints may be necessary at changes of background.

Who is responsible for ‘mastic’.

• Ensure correct adhesive is used. It must be suitable for tile, background and location.

• Do not use cement based adhesives or plaster.

• Tiles to be fixed with twisting or sliding action.

• Ensure correct coverage by removing tiles regularly. Wet areas require 100% adhesion, other areas minimum 50%; recommended 75% for kitchens, • 100% coverage normally requires the backs of tiles to be buttered as well.

• Ensure tile adhesive does not bridge movement joints.

• Do not allow adhesive to dry out prior to application of tiles, follow manufacturer’s recommendations.

Page 112

Avoiding Defects - Revision D – July 2013

• Is there a membrane under the tiles for floor gulleys? How does it seal into the gulley? Ensure this is sealed correctly so water doesn’t leak into the room below.

• Consider how the tiles are to be set out in the room.

• Avoid cuts in highly visible areas / corners.

• Where should full tiles be set out from?

• Does the wall tile joints line up with floor tile joints?

• Consider batching of tiles, some shade differences may be noticed if tiles are from different batches.

• Make sure you don’t tile half a room then change batch for 2nd half.

• Consider setting aside spares for various rooms / areas for replacing damaged tiles during snagging.

• How are tile edges finished? Do the tiles need a glazed edge or is there a plastic / metal edge trim required.

• How do edge trims join?

• Make sure tilers clean up as they lay, don’t leave over-spilled adhesive to dry on face of tile then try to clean after, especially textured surface tiles, you will either not be able to clean them or damage the face of the tile trying to.

• Movement joint trims to be fixed adequately, some manufacturers state mechanical fixings every 300mm, if not fixed correctly tiles will move and crack.

• Make sure tiles are fully bedded; particularly in highly trafficked areas, i.e. door thresholds.

Reference documents: BS 8000-11.1 – Code of Practice for Floor & Wall Tiling – Ceramic BS 8000-11.2 – Code of Practice for Floor & Wall Tiling – Natural Stone

Avoiding Defects - Revision D – July 2013

Page 113

30.0

Suspended Ceilings

Pre-construction • HOLD A COLLABORATIVE PLANNING WORKSHOP • During the procurement period examine the services above every area that has suspended ceilings. Among the items that need checking are service crossovers, service support / hangers and whether some work will still be required after the tiles are installed (e.g. second fix electrical work / BT and data).

• Procure spares to cover damages and, if required, for the client.

• There will generally be a requirement for patresses to be supplied for the installation of small lights, fire detectors, alarms, speakers, security etc fitted to ceiling tiles.

• If the ceiling is a plasterboard M.F. type with services above check requirements for access hatches – if not allowed consider programme and move items that require access to risers etc. contact British Gypsum.

• Check in detail the larger service ducts for both line and level.

• Consider requirement for bridging services or secondary grid.

• All pipe lagging and testing should be finished before the tiling itself is installed.

• Ensure all M&E works apart from final connections are complete before suspended ceiling works commence.

• Check light fittings are compatible with ceiling grid.

• Allow for installation of service tiles to suit M&E and final tiles as late as possible.

• Ensure fire curtains and fire stopping to fire walls etc are completed prior to ceiling work.

• Consider ‘applied loads’ by services or will they be self supporting.

• Consider ‘view thro’ – is a ‘blackout’ required.

• Allow for the following visits – o Grid o Service tiles o Final tiles.

Page 114

Avoiding Defects - Revision D – July 2013

• Do you need to build items early? (e.g. bulkheads).

• CEP tiles do not need clips. Their density makes them heavy enough to withstand the required volume of air when tested.

Construction • All services that need checking for level not just large ones.

• Ensure that M&E works are fully complete before tiles are installed.

• If light fittings etc are not modular ensure that the ceiling grids are enhanced to allow for the suspension of these fittings.

• M&E subcontractor needs to provide a cutting list for their service tile requirements.

• Check that the ceiling will carry the overall loads that services will impose on it.

• Ensure reflected ceiling plans are issued which clearly indicate setting out of ceiling.

• Setting out both vertically and horizontally requires extra care; even margins are the first objective.

• Examine how the ceiling meets the wall plaster. If there is no shadow batten the plaster requires to be true. If you have a shadow batten, point it before you fix it to the wall.

• Be aware that ceiling tiles can be susceptible to moisture. Tiles will sag if affected and will have to be replaced.

• Ensure ceiling grid installations.

supports

are

not

attached

to

M&E

• Be aware that to comply with certain fire ratings, ceiling tiles may require clipping. This will make future access difficult.

• Check fixings / type and centres are compliant with the specifications.

• Arrange fixing pull out tests.

Avoiding Defects - Revision D – July 2013

Page 115

31.0

Painting and Decorating

Pre-construction • Ensure compliance with specification.

• Ensure all areas are complete before the decoration commences including snagging. This will save time later (fewer return visits and patchy work, less daywork sheets).

• Agree on protection of fittings, flooring etc before work commences.

• Ensure adequate lighting; provide artificial lighting where the existing lighting is inadequate.

• Are face filling preparation works needed?

• Allow for an additional coat.

• Agree substrate and extent of filling.

• Consider who removes and replaces intumescent strips. (Joiners preferred).

ironmongery

/

• Consider disposal of paints / tins.

• Consider group agreement – ICI. • Check ICI approved applicators. (only use Deluxe CP) • Consider use of paint cleaning station e.g. Dulux Trade Environmental Wash System • Agree programme and sequencing of works Construction • For softwood timber, the correct sequence is: knot, prime, fix, fill, prepare, and paint.

• Hardwood timber should be pre-sealed before fixing.

• Ensure all fixings are punched below the surface and screws countersunk.

• Use the appropriate type of stopper and filler depending on the substrate, finish and coating system.

• Comply with manufacturer’s recommendations with regard to thinning and ensure that paints or emulsions are not over thinned.

• Ensure all surfaces and materials to be decorated have had sufficient time to dry out.

Page 116

Avoiding Defects - Revision D – July 2013

• Clean off any splashes and marks immediately from finished surfaces.

• Retain paint for defect remedial.

• Consider paint type as patching can be difficult with some brands.

• Apply mist coat as early as possible.

• Consider using masking.

• Do bottoms of doors need to be sealed?

Wallcoverings • Make and get signed off samples early.

• Ensure samples are representative of the actual product.

• Do not commence wallcovering hanging until: o The work of all tradesmen, which may affect the surface to be covered is complete. o The surfaces to be covered have dried out. o The painting of adjacent surfaces is complete and dry.

• Wall coverings need to be ordered in good time, be wary of a client’s last minute changes.

• Wall coverings must come from a single batch to ensure a good colour match.

• The shade number should be the same for all coverings in a room. If change of a shade number is unavoidable this must be done on an internal corner, NEVER an external corner.

• Allow for wastage in hanging.

• WARNING - Understand lead-in times. A lot of manufacturers have lengthy shut downs.

• Understand temperature comply with them.

and

humidity

requirements

Avoiding Defects - Revision D – July 2013

and

Page 117

32.0

Secondary Steelwork

Ideally secondary steelwork should be minimal if design reviews are thorough as requirements should have been included on the main steel frame. But there always seems to be additional items required across a variety of packages.

Below is a list of items that commonly get added to secondary steelwork subcontract orders during the build to be aware of and possibly allocate to main steel design package.

• Match play basket ball goals supports – These generally need to be flush with wall and location/size depend on manufacturer.

• Support plates for incomplete design elements e.g. glulam beams that connect to main structure.

• Additional support beams for curtain walling – All parties are usually assured that sufficient support for curtain walling systems is designed into the main structure steel yet more often than not additional support is required.

• Window support angles – due to sequencing of works if bricks don’t go in first.

• Framing of large openings in external walls – generally M&E detailed design is still ongoing when steel design is almost complete.

• Trimming around flues/service penetrations – where coordination exercise has missed a few elements accidently or they have been introduced late.

• Support of full height partitions – where a larger stud size is not sufficient to stabilise partitions additional steel may be required.

• Stair support angles.

• Heads of disabled hoists – if client is late in providing information on which rooms they require hoists in this can lead to additional steel being needed.

•

Plant support steel work - this can include ductwork and tanks.

• Site testing of welds.

• Lifting beams - generally for lift shafts, but potentially during the build you need to install them to assist with raising other elements into place.

Page 118

Avoiding Defects - Revision D – July 2013

• Temporary supports to curtain walling – If curtain walling is due to be tied back to elements not yet erected a temporary steel may need to be installed.

• Decide whether there is potential to leave steel in place allowing other elements to have their specifications reduced.

Reference documents: BS 6180 Barriers in and about Buildings

Avoiding Defects - Revision D – July 2013

Page 119

33.0

Paint Finishes on Metalwork

Preconstruction • Refer to British Steel (Corus) corrosion protection guides.

• A paint protection system on plain steel must be first class (with 100% preparation and application), to be effective and durable. Similarly, any galvanised steelwork must be properly prepared to ensure any subsequent paint application works.

• Visit works to ensure steel preparation for painting is to specification. It may be necessary to involve a suitably qualified inspector for this.

• Avoid applying external paint finishes on site, if at all possible.

Conditions and preparation are rarely suitable or appropriate.

• White paints can yellow over time.

• Consider the use of water based paints as these are more stable but have less of a sheen.

Construction • If site painting has to be carried out, ensure tight control on preparation, ambient conditions, time between coats and curing.

• Ensure that all necessary priming/cleaning between coats is carried out correctly.

• Obtain detailed method statement for site remedials.

• Check paint thickness using dry or wet film gauge.

• Pay particular attention to places which are hard to reach when spraying, if possible use a brush or roller due to over spray being hard to control and the Health and safety factors involved.

• Never use galvafroid for making good galvanising. Use either 2 part zinc rich epoxy or low melting point zinc alloy repair rod.

It is essential that sufficient coats are used to give an equivalent zinc contents as the original,(min 90% zinc content of dried film).

• If site painting ensure that the factory applied primer is compatible with the finished paint

Page 120

Avoiding Defects - Revision D – July 2013

34.0

Carpentry / Joinery

Preconstruction • Consider need for temporary fire doors.

• Check specification.

• Organise a workshop with the architect and door supplier early to run through the door schedule and all details.

• It may be better to use a suppliers schedule.

• Pay particular attention to ironmongery and minimum opening widths.

• Ensure the storage conditions on site will maintain the moisture content and not create distortion.

• Check that the ambient conditions during and after fixing are suitable.

• In some situations, dehumidification may be required.

• Beware when using tanalised timber. The preservative could affect aluminium and galvanised fixings.

• Ensure datums are in place prior to fixing door linings.

• Consider hanging door then removal and reinstallation near handover.

• Check fire and security strategy – do you need a wire way or specialist cut out – will this affect the fire or acoustic rating.

• Plan and manage keys and handover to client.

• Have interfacing trades tolerances been considered in the design?

• Check intumescent or acoustic mastic is in place behind door frames before fixing of architraves Construction • Protect doors stored on site with solid boarding and affix notices to prevent use as hop ups or work benches.

• Doors and all timbers require particular care, i.e. storage must be dry and humidity control is vital; doors should ideally be stacked flat on timber bearers.

• Consider the use of sacrificial temporary doors for fitting of frames where door sizes are standardised, enabling delivery of doors to site to be delayed.

Avoiding Defects - Revision D – July 2013

Page 121

• Check grades of timber delivered to site complies with design.

• Measure the moisture content at delivery and ensure compliance. Any shrink-wrapping must not be damaged.

Protection must be fire retardant to LPS 1207.

• Remember that most timbers move dramatically with changes of heat and moisture.

• Most timbers need to be ‘balanced’, i.e. do not use a veneer or sealer on one side only. Apply treatment between frame jamb and head.

• Obtain and check the confirmation of any treatment applied to timber.

• Ensure cut ends or cut outs of treated timber are re-treated on site.

• Check door linings after fixing as twisting of parallel edges can be easily spotted.

• Is the correct fire certificate available for the fire doors? Glass panels are to be kite marked.

• With regard to fire rating ensure correct doors are fitted to frames.

• The door manufacturer should execute off site the penetration apertures for doors / frames to receive site fixed locks / hardware.

• Beware of warping on external doors.

• Use medium to high build stain to all faces or edges, or consider using a cladded door with steel core.

• If using hardwood-veneered doors pair matched for grain and colour, ensure doors are correctly paired.

• Beware that MDF board can move excessively compared with plasterboard. Make provision for this movement. Always use moisture resistant MDF. • Are pellets and dowels the correct colour with grain aligned on clear finished timber?

• Check that roof trusses are fitted in the correct locations.

• Ensure that bracing has been designed and fitted for any temporary roof trusses - bracing required should be ‘designed’.

• Protect finished joinery from possible damage.

• Beware effects of plaster on hard wood frames.

Page 122

Avoiding Defects - Revision D – July 2013

• Do you need a drop down seal?

• Check that cut outs do not affect structural integrity.

• Ensure and tongue and groove is given a 1st coat before fixing.

• Do you need any cut outs for louvres or undercuts to doors.

• Consider the positioning of doors adjacent to corridors for example. Recessing doors can avoid the need for restrictor devices which are prone to damage. This can also prevent door stops from becoming a trip hazard or the need to install barriers. See picture and sketch below.

• Delay fitting of WC duct panels as long as possible, fit only “trapped” panels in conjunction with sanitary ware installation.

Fit removable panels after completion of M&E works and operate a permit to work system thereafter.

• Ensure sufficient supports are designed in to dry lined walls for fixtures and fitting, particularly drop down rails to disabled WC’s.

Reference documents: BS/ EN 336 - Structural Timber – Sizes, Permitted Deviations BS 5268-2 – Structural Use of Timber – Code of Practice for Permissible Stress Design, Materials & Workmanship BS 6180 - Barriers in & About Buildings Avoiding Defects - Revision D – July 2013

Page 123

35.0

Road / Hardstanding – Concrete

Pre-construction • Determine which materials need frost susceptibility checking.

This test can take several weeks if recent certificates are not available.

• Ensure formation is suitable and to specification.

• Ensure the sub-base and capping is in accordance with the SHW. e.g. material, thickness, compaction.

• Check specification understood.

for

the

capping

/

surface

finish

is

• Is the surface tolerance compatible with the overlying layers?

• Have all services / ducts and drains required been installed (consider spares)?

• Ensure joint positions have been properly considered.

• Allow for movement against kerbs, manholes, and gullies, etc.

• Is the finish on concrete specified? This should be to an agreed sample or standard. Ensure standard of tamp / brush is consistent and is in the correct direction for abrasion and water run off.

• Check that all dowel bars are ordered as ‘sawn ends’.

• If ‘lap build-up’ is likely to cause a problem check that all mesh reinforcement is ordered with ‘flying ends’.

• Consider aggregate type for road use e.g. basalt for tracked vehicles.

• Is air entrained concrete required – check testing regime.

• Check that sufficient anti-crack bars are detailed at manholes / gullies.

• Is lime stabilisation an option?

• Can sub-base and subgrade construction traffic / plant?

withstand

the

loads

from

• Consider changing to a higher quality material to allow continuity in poor weather.

• Do not use flexcell etc. without support of shutter.

• Consider using Kier Engineering Services or the ‘Concrete Advisory Service’ for assistance / advice.

Page 124

Avoiding Defects - Revision D – July 2013

Construction • Ensure all pokers are in good working order before pouring.

• Obtain approval of mix designs (air entrainment, additives).

• Proper compaction of materials requires close control of moisture content.

• Are kerbs the specified type?

• Ensure haunching to kerbs leaves sufficient depth for finishes outside (consider manual handling).

• Check reinforcement is properly fixed – mesh requires supports at close centres (600mm approx).

• Check top cover before / during pour.

• Will a suspended cover be required to maintain the surface finish should it rain?

• Ensure dowel bars fitted with compression caps in expansion joints and that they are grout tight.

• Ensure dowel bars are level, square, parallel and to specified accuracy.

• Also check dowel bars are properly coated including underside and correct number of coats of specified de-bonding material.

• Consider access requirements to ‘trowel off’ around manholes etc when they are in the middle of a poor.

• Cure concrete very well. Consider using polythene as well as spray applied membrane.

• Saw cut any joints as soon as possible after hardening, max 24 hours depending on materials. Too soon will pluck out the aggregates.

• Ensure rebates for sealants are sufficient & that the correct sealants are specified & applied properly.

Reference documents: Concrete – Kier Technical Guidance Note TGN 5 – Concrete Advisory Service TGN 9 - Preparing, curing & Testing Cubes TGN 10 – Recording Concrete Cubes Correctly TGN 10 Form 2515a – Concrete Cube Results Analysis Example

Avoiding Defects - Revision D – July 2013

Page 125

36.0

Road / Hardstanding – Asphalt

Pre-construction • Determine which materials need frost susceptibility certificates as this test can take several weeks. Check the specification Vol. 1 Specification for Highway Works (SHW) • Can you reduce depth of non frost susceptible material with a frost index for the site (available from the Met office)?

• Ensure formation suitable and to specification (proof rolling etc).

• Agree levels prior to start of any area.

• Is the Asphalt to be machine or hand laid? Hand lay can be very variable so avoid if possible.

• Is the wearing course suitable for its application?

• Is the thickness compatible with the size of aggregate? Seek guidance.

• Arrange for sampling and testing to check grading and binder contents of base course and wearing course.

• Don’t be afraid to query levels and falls with the designer as they are not always easy to interpret using datums.

• Consider using council approved contractors for council works.

• Is a surface dressing required? Understand specification for black top – is it compatible?

Construction • Have all services / ducts and drains required been installed?

• Ensure sub base and capping is to specification, material thickness, moisture content, compaction in accordance with the SHW. • Is the surface tolerance compatible with the overlying layers?

• Check delivery and laying temperature of bitumous materials against the specification BS594987. o Delivery base 150/195°C, wearing 160/195°C approx. o Laying – base 110°C, wearing 130°C approx.

• Allow for the cooling effects of wind.

• If open flame is being used a hot works permit is required. This includes the paver reheating the tar / asphalt.

Page 126

Avoiding Defects - Revision D – July 2013

• Check the temperature of the tarmacadam using an appropriate thermometer especially if it’s been standing for a while and is being hand laid.

• Compaction of materials requires close control of moisture content.

• Ensure compaction is to the specification. (use SHW as the default).

• Check that the preparation of all joints in base and wearing are correct and that joints offset a min of 300mm from those below.

• Ensure adequate spread of chippings in hot rolled asphalt (usually 10-14kg/m2).

• Check that all edge joints have been cut properly, cleaned and tack coated.

• Check that the bituminous thicknesses have been checked by dipping.

• Ensure diesel is not split as this can degrade the surface.

Reference documents: BS 594987:2010 -

Asphalt for Roads & Other Paved Areas –

Specification for Transportation, Laying, Compaction & Type Testing Protocols Specification for Highway Works (SHW)

Avoiding Defects - Revision D – July 2013

Page 127

37.0

Soft Landscaping

• Check contract / specification for landscaping requirements.

• Check contract / specification for primary drainage requirement and that any drainage can accommodate additional drainage provision.

• Ensure level of soft landscaping does not compromise any adjacent dpc.

• Ensure the gradients of the surface are within permissible limits.

• Ensure the correct grade of topsoil is applied and records of adherence to the relevant British Standard are retained.

• Ensure that any retained soil heaps are kept in good condition and not contaminated and that size and quantity of stone is within prescribed limits.

• Do not exceed specified height of soil heaps.

• Establish the responsibilities for the extent of weeding of soft landscaped areas and irrigation.

• Establish the contract maintenance / defects period for landscaping. Who is responsible for replacement if planting dies?

• Are the trees positioned such that they will not compromise CCTV visibility when the trees mature.

• Confirm that all plantings meet specification with regard to plant species and maturity.

Page 128

Avoiding Defects - Revision D – July 2013

38.0

Sports Pitches

• Check contract / specification for landscaping requirements.

• Check contract / specification for primary drainage requirement and that any drainage can accommodate additional drainage provision.

• Sport England provide guidance on the various aspects of design and installation and are sometimes referred to in contract documentation as the minimum requirement.

• Ensure the gradients of the surface are within permissible limits.

• Ensure the correct grade of topsoil is applied and records of adherence to the relevant British Standard are retained.

• Ensure that any retained soil heaps are kept in good condition and not contaminated and that size and quantity of stone is within prescribed limits.

• Do ntexcced specified height of soil heights.

• Ensure that the size of the pitch and any run-off can be accommodated making particular provision for manhole covers.

• Correct timing of the works is essential to ensure viability of the playing surface.

• Clearly establish who is responsible for the maintenance of the surface between cultivation and handover of the sports field particularly in the event of drought.

• Who is responsible for the initial white lining?

• If the field is to be multipurpose use, is field furniture such as rugby posts to be removable?

• Provide clear maintenance obligations as part of the handover pack including guidance on number of cuts, rest periods for the surface and sand blinding, scarifying and fertilizer.

• Is there access for maintenance equipment via suitably sized gates?

Avoiding Defects - Revision D – July 2013

Page 129

39.0

Raised Access Flooring

Pre-construction • Procure perimeter cutting for radiator pipes, columns etc.

• Procure perimeter soft joint.

• Procure earth bonding for static electricity.

• Procure mechanically fixing pedestal should T42 (bag test) test fail.

• Procure surface finish of sub-floor – light tamp for a key to the epoxy adhesive.

• Procure floor level tolerance adjustment in pedestal.

• Ensure lifting devices are obtained for use by Kier and issued to client on completion.

• Procure – fire retardant protection.

• Consider Group Agreement with Kingspan.

• Kingspan provide technical support & information on their website www.kingspanaccessfloors.co.uk • Procure off site cut outs for floor boxes – off centre position in tile for flexibility in use – ensure cut edge is sealed.

• Procure spares and consider storage.

• Are cavity barriers required?

• Is sealing of concrete floors required? (How many coats) • Where more than one coat of sealant is required use different colours as a control.

• Ensure system is not a prototype (unproven).

• Plan in advance how the installed floor is to be protected. The client has bought a new product.

• Plan the sequence with Building Services.

• Define attendances for lifting and replacing tiles.

• Understand where access is required both for commissioning and maintenance.

• Consider oversized tiles at perimeters for example, to avoid small cuts.

• Review design for steps / ramps in floor.

• Review design for acoustic barriers between offices.

Page 130

Avoiding Defects - Revision D – July 2013

• Some tiles (vinyl) can have floor finishes factory bonded.

• Consider pre-marked pedestal positions for heavily serviced floor voids.

•

Check preloading limits of floorings early and distribute evenly.

Construction • Floors must not be laid until building is watertight.

• Ensure void is clean and vacuumed.

• Is there any bridging of services.

Avoiding Defects - Revision D – July 2013

Page 131

40.0

Acoustics

Useful definitions: Rw is the standardised lab rating given to a partition. It is standardised by taking out the influence of the rooms (reverberation times and area of separating elements) in order to compare the performances of difference wall types, so workmanship/flanking/etc will not influence this rating.

Rw’ is the standardised in-situ rating for the above partition, but due to being in-situ, will include influence of workmanship/flanking/etc.

Therefore it is normally expected that the Rw’ will be 5 to 8 dB below Rw Dw is simply the measured level differences between two rooms, and is also inclusive of workmanship/flanking. However, Dw is different to Rw’ in that the Dw is unique to a particular room on a particular site. The Dw is also normally expected to be 5 to 8 dB below that of the laboratory rating. On site variables include flanking routes on all sides of the partition, background noise, workmanship details down to size of screws, angle of studwork, electrical fittings, power points, etc, all of which contribute towards the 5 to 8 dB difference.

NRC or Noise Reduction Coefficient, is a measure of the acoustic absorption of a material and is equivalent to the arithmetic average of the sound absorption coefficients in the 250 – 2 kHz octave bands.

Pre-construction • Understand our contractual obligations. Do we need to confirm ratings by testing before handover or is ‘robust detailing’ acceptable?

• Are there specific frequency requirements in the specification?

• Do flanking tests have to be carried out on the façade or partitions?

• Consider using an acoustic consultant to review architectural and subcontractor’s details and on-site installation. Particularly if there are some non-standard installations.

• What are the planning obligations – usually given as an acoustic reading above baseline X metres from the perimeter of the site? This usually relates to plant noise.

• Are there specified acoustic ratings from building to outside (e.g. planning), outside to inside (façade), internal to a room (reverberation), between rooms (wall, door ratings) and through the fabric/structure (flanking/structure-borne)?

Page 132

Avoiding Defects - Revision D – July 2013

• Pass the responsibility for acoustic performance of items to subcontractor where appropriate.

• Be clear on which takes precedence in event of discrepancy between contract documents and specifications etc. e.g.

Acoustic spec vs architectural spec.

• Ideally ask the architect to refer to the acoustic spec!

• Understand what the clients’s expectations are even if we have not signed up to an acoustic performance between rooms, as Rw ratings for the separating walls are specified the client will have an expectation that they are getting an acoustic separation (Dw). The rating through the partitions is relatively high so flanking routes have a relatively higher significance.

• Are there any situations where we have a flanking route between floors, between the slab and some façade?

• Are there flanking routes through the mullion and also routes through the glass as structure borne, as well as break out and break back in?

• Review Back Boxes – Do you need putty pads?

• Any penetrations through walls need to be acoustically sealed – the higher the rating the better the product and solution.

• If placing the responsibility of sealing builder’s work in MEP package, make sure the acoustic strategy/spec is in their order.

• What testing is required? When can testing be carried out?

• See section on ‘Drylining’ also.

• Consider the sequence if there are ‘acoustic’ ninterfaces with the ceiling.

• CEP will provide assistance on acoustic performance of ceilings, baffles, etc. Use them.

• Before detailed design commences there should be an acoustic strategy in place which has been signed off by the client.

Therefore all consultants can design with this in mind.

• Acoustic strategy to be signed off by building control.

• For schools Building Bulletin 93 sets the criteria for acoustics.

The design needs to be reviewed with that in mind, Any areas that cannot be complied with need to be derogated against with client acceptance.

Avoiding Defects - Revision D – July 2013

Page 133

• Ensure everyone is made aware of derogations so elements are not acoustically over specified.

• Mechanical ventilation systems must achieve BB93 under all conditions.

• Door and internal glazed screen schedules to be thoroughly reviewed so they are specified with correct dB rating as per strategy.

• Consider what is required for acoustic testing. It is good practice to have a definitive list of what needs to be tested • Who is going to carry out the testing and when • Intermediate checks as work progresses will ensure compliance with strategy and possibly pick up un-identified acoustic interfaces.

• Establish points in job when you want the acoustician to visit – when partitions start – head details, specialist spaces – noise sensitive, before ceilings are closed up etc.

• Review sequence of works if double acoustic ceilings are required in specialist areas e.g. kitchen/music room etc as this may have to be adapted.

• Rationalise service runs or need for attenuated ductwork with acoustics in mind when developing M&E design.

• External acoustic survey should be another driver for façade used and class room uses.

• Consider rain noise on roof lights. There is no performance standard currently in BB93 but building control will require demonstration that the design minimises rain noise.

• If roof lights are specified in teaching rooms chose material carefully e.g. glass in classrooms, polycarb in circulation areas.

• ETFE roofs act like drums in rain so consider rain noise suppression.

• Rain noise suppression may be excluded when tendering for work due to associated cost increase, but include this in subcontract enquiries.

• If no ceiling is specified in a room how will you dampen sound? i.e. perforated deck and profiled acoustic fillers which means some of the sound is absorbed rather than bouncing around.

• Room to room transfer – workmanship of head and jamb details for partitions, also seek guidance from the technical Page 134

Avoiding Defects - Revision D – July 2013

advisor of drylining system used – As a supply chain partner British Gypsum are very willing to assist on advise for details.

• Is there a risk of roof plant noise travelling down through building? Explore possible options i.e. plinths etc.

• Is a m2 standard rate of acoustic material needed in rooms at specific ratings given? How will you accommodate the meterage? Ceiling tiles/acoustic panels/acoustic cubes/acoustic internal cladding.

• Acoustic panels are sometimes fitted at the last minute to achieve correct area of absorbing material. Elevations should be requested to ensure it all fits and is co-ordinated with installed M&E and any other elements mounted in rooms.

• Avoid spray applied acoustic treatments as they damage easily.

• Challenge the ceiling specification – is it the most effective or appropriate?

• Confirm the level of sound emitted by plant as there may be a requirement later on for expensive enclosures.

• Detailed sequencing may be required with steel structures when sealing acoustically. measure any M&E routes.

• Have mock-ups been tested?

• Pivot doors do not work well with acoustic seals.

• Clarify that rooms with high acoustic ratings will have hinged doors (not pivoted) so the acoustic seals can be activated (drop seals etc).

Construction • Establish a robust checking procedure as revisits to seal gaps are costly.

Avoiding Defects - Revision D – July 2013

Page 135

41.0

Furniture, Fittings & Equipment

Pre-construction • Refer to legislation and byelaws including Category v % water supply backflow protection.

• Check the schedule of FF&E and ensure that the quantities and specification you are buying against matches the specification in the Contractor’s proposals/Client’s room Data sheets.

• Ensure electrical equipment such as blinds etc with remote control have relevant power supplies & switches fitted by M&E subcontractor.

• Confirm with the Client / End User that they understand that domestic white goods do not have warranties.

• Ensure that, replacement of defective white goods during first year defects period is built in to the price as a risk sum.

• Ensure that any CP documentation is cross referenced before procuring particular models of FF&E equipment. Most electrical products will have obsolete model numbers due to the time taken between issuing of CPs and placing of orders.

• Ensure that there is a client confirmation that they are happy with the revised product before placing the order (even if there is no change in cost).

• Consider the delivery and installation of machinery early.

• Ensure that there is clear unrestricted access (door and corridor widths) from the delivery vehicle, through to the item’s final location.

• Consider kilns for one piece delivery inc access and door widths.

• Consider drawing co-ordination and revision status to ensure all parties are working to the correct drawings, The architects overall coordination role is essential of layouts / services etc.

• Ensure correct or suitable product selection i.e. coordination of chair or stool feet with selected floor covering ensuring against excessive wear or damage.

• The Equality Act / Fire escape to be maintained – Architect / Fire engineer to coordinate.

• Ensure the final connection has been discussed with the M&E/FF&E contractors to ensure electrical certificates and chlorination certificates are obtained and coordinated.

Page 136

Avoiding Defects - Revision D – July 2013

• Ensure that responsibilities for earthing, traps and final connections are understood.

• Ensure that suitable pattress requirements are detailed, installed and signed off prior to closing up the dry lining.

• Ensure that the guidance of BB81 is achieved in that the safe working distance between machinery is not compromised.

• Ensure any machine or product can be located in the correct location at completion. An early delivery may be required.

• Ensure the correct floor loadings are adequate for machines to be installed onto.

• Ensure good communication is maintained throughout, from design to installation especially where there are M&E interfaces.

• Have Ofsted recently updated their regulations for equipment or due to do so? Applies mostly to technology equipment.

• Does the local water board require white goods e.g. washing machines and dishwashers to have WRAS certification?

• Are tumble dryers required to be condensing or vented?

• Early selection of specialist equipment with M&E interfaces is needed to progress M&E design i.e kilns, fixed fume cupboards, sound and light equipment.

• Are cleaners sinks included in FF&E or M&E supply?

• Is sports hall line marking included in FF&E or build costs?

• Has sufficient support for the installation of any wall mounted sports equipment e.g basketball goals, been included in structure?

• Support steel for wall mounted sports equipment should be flush with walls.

• To ensure that support steel is correctly located the sports hall FF&E package should be placed before the steel frame design is complete otherwise it will need to be added to secondary steel work scope.

• If benching is placed in front of windows – do not assume it is cill height – check it! If it is floor to ceiling and cannot move then a solution will need to be developed.

• Check if any of the loose furniture required needs to be fixed back to the wall – if it is over 1800mm high, best practice is to secure the items back to the wall.

Avoiding Defects - Revision D – July 2013

Page 137

• As best practice, any item of furniture that is over 2m tall should have a step up stool.

• Loose furniture regularly clashes with dado. It is recommended that a co-ordination meeting is held and the heights of loose items confirmed.

• Check architects patress drawings to ensure they have picked up all requirements.

• Decide dust extraction strategies early in project to ensure that equipment is properly supplied and costed. Is the strategy to have ducted technology equipment or localised dust extraction?

• Inform client that localised extraction to bench mounted technology kit will use under bench cupboard space.

• Ensure that the person responsible for the FF&E package is notified every time the architects update the general arrangements.

• Ensure that the FF&E sub-contractor carries out a site survey before the production of manufacturing drawings to allow for all box outs etc.

• Be aware that the lead time of items varies from 4 to 18 weeks.

• Manage the client’s expectations and issue a project specific catalogue and samples to them early.

• Where possible select skid based chairs and stools as heavy duty 4 legged stools and chairs can easily damage vinyl floors.

• Clarify all heights of furniture with client.

• DDA requirements can change. depending on contract requirements and building control officer. Does every surface need to be a contrasting colour for fixed benching etc?

• Do Blinds sit in reveal? If so consider possible interfaces with Teleflex cables and winders, low level heaters.

• Black out blinds are required to sit in reveal and are completely frames out – potential clash with Teleflex cables etc • Is the blind specified accurately for the span required?

• Ensure client comments not related to FF&E are passed onto appropriate team members to action.

• Set up a clear method for tracking changes.

Page 138

Avoiding Defects - Revision D – July 2013

• Be aware that late changes to FF&E layouts – even just moving a cupboard - could potentially have an M&E/structural impact.

Always confirm with team and client what is possible before agreement.

• Co-ordinate with client on potential legacy equipment as interfaces will need to be identified early.

• If safes are present has the slab been designed to take the point load?

• If a safe is not on the ground floor how will it be taken upstairs?

• In designs with underfloor heating any items requiring finxing to the floor will need to be identified to the designer.

• Aim to have ceiling in place before the fixed furniture is installed thus avoiding the risk that the ceiling fixers will walk along the tops of the FF&E and cause damage.

• When rooms are completed with fixed furniture a permit to work system should be instituted to track any damage caused e.g. to worktops.

• Has the FF&E supplier been given an up to date site logistics plan and been made aware of delivery points into the building?

• Remind FF&E suppliers that Kier do not sign for deliveries and expected delivery timetables are required – their outsourced items generally get delivered whenever their supplier feels like it which can make site planning awkward.

• Consider a site based FF&E co-ordinator during installation to liaise with all section managers and discuss and agree work sequence with them.

• During design/detailing suiting/unsuited keys.

agree

requirements

for

Construction • Always ensure you are working to the latest drawings, i.e. sockets behind units and next to taps.

• To improve installation of fixed furniture, rooms must have flooring down, the ceiling in and a mist coat applied to the walls.

• Measure the moisture content if timber at delivery and ensure compliance. Any shrink wrapping/protection must not be damaged. [All protection must be fire rated as per Red Top.] Avoiding Defects - Revision D – July 2013

Page 139

• Ensure the storage conditions of timber on site will maintain the moisture content and that the ambient conditions during and after fixing are suitable. In some situations, dehumidification may be required. Also check that storage conditions do not create distortion. [May need to be just in time deliveries, i.e. split not bulk.]

• Remember that most timbers/boards move with changes of heat and moisture. Most timbers/boards need to be balanced, i.e. ensure a veneer is not used on one side only.

• Do not apply a sealer on one side only.

• If damage is possible protect the finished products, especially work tops if in front of windows.

• Ensure cut outs or cut ends on worktops are treated and re treated if necessary on site.

• Ensure all shelves are fitted to cupboards with correct amount of clips prior to sign off.

• White goods in particular can change their specification from month to month and care should be taken to ensure that the correct model number is being procured/installed.

• Make sure infill panels are allowed for especially if cupboards are set off from the wall and make sure cupboard and panel match.

• Ensure the end panels of cupboards match the main unit carcass.

• Check that radio controlled clocks actually work.

• Ensure the slip resistance of floor finishes is suitable in workshop areas as dust and wood chippings from machinery can affect the slip resistance.

• Ensure that welding bays are painted dark matt grey to avoid reflection when welding is in progress.

• Ensure extraction units are well sound proofed if located within the classroom.

• Label and secure all keys as they are produced.

• Ensure operating manuals/maintenance sheets are captured for inclusion within the O&M’s especially • Ensure all cupboard doors/draw units etc are checked for operation and properly fixed prior to sign off.

Page 140

Avoiding Defects - Revision D – July 2013

• Do not replace a layer of plasterboard with ply as a patress between the studs as this may have acoustic implications.

Avoiding Defects - Revision D – July 2013

Page 141

42.0

School Kitchens

Design • Ensure that a brief is received from the client regarding pupil numbers, length of break, Split lunches etc.

• Consider how meals will be paid for, pay as you dine or swipe card system, as this affects flow through the canteen tills.

• Consider use of specialist kitchen consultant.

• Appoint specialist kitchen consultant early in design process to provide knowledge and co-ordinate the design based on Client brief & market knowledge. They can advise on equipment suppliers, complicated installations – ventilated ceilings, value added and whole life cycle cost benefits. They need not be used for installation. A Specialist S/C can be used to support this role but may not give best advice.

• Define scope (e.g. design only, design and fit out) early ensure that design responsibillty is co-ordinated.

- Architect - layout - M&E Consultant, service supply sizes, ventilation strategies, equipment performance characteristics. provision of services & supplies for kitchen fit out - Specialist Design/Kitchen Consultant design co-ordination •

Architect to agree and produce detailed room layouts showing co-ordinated fit –out.

•

Who is providing the FF&E?

• through all stages of process.

• Scope should include requirements for testing & commissioning of kitchen systems, together with proving M&E supplies, gas, water pressure, power supplies.

• Are there any additional areas to develop early e.g. re- heat kitchens, snack bars, demo areas since M&E will require locations.

• Consider specialist installations, ventilated ceilings, drainage requirements, local dosing units, grease traps, co-ordinate these with Building Control and Environmental Health.

• Has an alternative dosing system been considered for grease traps?

• Who maintains the grease trap and what is the service interval?

Page 142

Avoiding Defects - Revision D – July 2013

• Is the grease trap located internally or externally?

• Consider kitchen performance as part of the overall building performance e.g. Building Regs – Air-tightness tests.

• It there a requirement for training areas within main kitchen – NVQ – GCSE cooking areas.

• Does design avoid cross contamination? i.e. between fresh food and dirty plates etc.

• Consider Management of food waste, compaction, water reducing units, bio-mass.

• What are the wall finishes- ceramic tiles, hygienic wall panels, White-rock etc.

• Seek advice from the kitchen consultant regarding Environmental Health, storage and receipt of raw food products and coldroom / freezer requirements.

• Consider the fresh air supply and extract system to ensure there is no cross contamination through the supply and extract grilles.

• The external environment should be considered. It is preferable to locate the kitchen/canteen away from water course, ponds or irrigation ditches, this includes swales used to attenuate surface water drainage in flood or high water condition.

• Consider client signoff requirements in specification. This may be required through key stages of the design process and during equipment manufacture and testing, off site validation testing.

• Ensure that the specialist signs off M&E design before works commence on site.

• Review fire strategy and understand compartment definition.

• Is there a requirement for fire suppression? This may include suppression systems with duct works either in the kitchen space or within the plantroom • Are above ceiling -fire enclosures ?needed to perimeter of kitchen? Consult with Building Control.

•

Consider ventilation strategy with the design team.

• Ensure fire suppression strategy is in line with fire strategy signed off by building Control and client.

• Is there clear access to the fire dampers?

Avoiding Defects - Revision D – July 2013

Page 143

• Are fire dampers manual or automatic reset type?

• Do powered dampers need an alternative or auxillary power supply?

• How do fire dampers link to the fire strategy, BMS systems, alarms interface?

• Once canopy selection has been made try not to change since M&E design will need to check locations of equipment and floor gullies on every drawing in relation to equipment location and servicing needs.

• Has adequate support for the canopy been designed?

• Ensure that structural engineer checks fixing bolt calculations for adequacy.

• Is temporary works required to install canopy and ceiling finishes around canopy?

• Consider automatic / manual canopy wash down systems, air flow rates through canopy, gas isolation valves generally linked to AHU’s.

• Is FR ductwork required on extracts? Refer to fire strategy, fire suppression system, Building Control review of fire strategy.

• Clearly identify on kitchen drawings what is not being supplied by specialist.

• Ensure architects base layer matches kitchen layout provided by specialist before construction begins.

• Review if hygienic wall finishes and finishes to all joinery items, doors and frames is required.

• Discuss with the Kitchen Consultant and M&E Specialist the ventilation strategy to determine the extent. Air flow rates, size of air handling plant to be considered and sized correctly.

• If the ductwork, riser configuration or air plenum leaves the kitchen and passes through circulation areas insulation may be needed to stop radiating off them.

• Has a power supply been allocated?

•

Is additional impact protection required such as bump rails for trolleys, corner guards to trolley bays, ceramic floor and wall tiles.

• Ensure slab dropped 150/200mm lower at built in freezer positions to allow for insulation.

Page 144

Avoiding Defects - Revision D – July 2013

• Determine which subcontractot is to have in scope the floor finish, insulation, screed & tiling, generally this is not the coldroom installers.

• Ensure that the Project BREEAM Consultant advises on BREEAM credits associated with kitchen / catering installation • Is the scheme hoping to collect BREEAM point for insolent Gap’s? These are required to be 5 or less which may not be cost effective.

• Ensure that the correct commissioning requirements are written into scope for management. BREAAM - 1 credit.

• Ensure power/drainage requirements relevant to signed off kitchen design is incorporated by consultants.

• It may be best practice in the future to fit enzyme injection to assist with maintenance of drainage.

Construction • When using white rock it is easier to do all chasing first so there is no waste.

• Keep the number of surface mounted conduits to an absolute minimum in order to improve infection control, see best practice guidelines from HTM. • It is best practice to avoid surface conduits to improve hygiene/cleaning.

• Consider sequence of ceiling installation – if it is last, can they safely install grid and tiles without damaging installed kitchen equipment?

• Ensure ceiling is not fixed to M&E ducts etc which may move and damage ceiling at a later date, • Co-ordinate sequence of ceiling installation with M&E works, sprinklers, smoke/fire detection, auxiliary ventilation- supply and extract.

• The typical heating for commercial kitchens is warm air supply with grills in the ceiling.

• A WRAS (water regulations advisory scheme) certificate will be required for relevant equipment.

• Ensure correct notation / colour code is used for duct work labels to avoid confusion, supply air, extract, dirty extract, chilled supply etc, Avoiding Defects - Revision D – July 2013

Page 145

• Review specification and ensure that duct supports are at the correct centres, access and maintenance hatches within duct work at correct specified locations.

• Ensure that there are no sharp edges left inside access hatch when post fitted to ductwork.

• Is In-situ welding needed? Confirm access into area.

• Custodial premises do not permit cuts to tiles around gullies so non- standard specials may be required.

• The setting out of floor tile to be co-ordinated with equipment installation and drainage detailing • Consider how the floor will be cleaned, and slip resistance when wet.

School Food Technology • Has a clear scope been given by client i.e. how many pupils in space, number of work stations required e.t.c.

• Is a demo bench needed, is there going to be an interactive white board fixed to wall or on mobile trolley.

• Make client aware that wall space will be taken up by required M&E elements i.e. localised distribution board, gas cut offs etc, kitchen race-ways to include localised dis’ boards, gas shut off valves, services access points etc.

• Does the local water board require WRAS certificates for domestic white goods (cost uplift since only a few comply) – not all request this.

• The curriculum requires half gas and half electric ovens • Check with building control that the layout agreed with the client satisfies fire strategy and escape route requirements.

• At least 1no work station, to include sink, work top and oven, will need to be height adjustable to be DDA compliant.

• If the DDA height adjustable sink has a hot tap there may be a need to insulate bottom of sink to avoid scalding to pupils.

• If using white rock ensure all M&E fixings have been allowed for.

• Review heating strategy. If radiators are being used, where are they located? Do they clash with benching and grill required to benches?

Page 146

Avoiding Defects - Revision D – July 2013

• The standard layout places ovens in peninsular benching.

Consider how will they be serviced. If this is through cupboard service voids/ holes left in slabs then early precise setting out will be required. The sequencing of M&E installation is to be considered depending on choice • Have enough power supply’s been allowed for other equipment microwaves/blenders etc.

Avoiding Defects - Revision D – July 2013

Page 147

43.0

Lifts

General • Aim to get ALL work in the shaft done by the lift contractor.

• Confirm that suitable and lockable three phase and single phase power supplies will be available.

• Confirm that temporary three phase power supplies provided for lift installation is protected by a 500mA RCD (per lift).

• Confirm access is safe with dry secure storage provided (8MX3M PER LIFT).

• Lifts usually require a dedicated analogue telephone line for commissioning and use. This is a long lead item so needs to be considered early. If the telephone line is not available for use then provision of a radio and operator may be required.

• Confirm that the telephone line will be provided to suit programme of testing and who is responsible for this.

• Ensure telephone system is compatible with lift.

• Consider beneficial use; protection; re-fits; re- commission; and extended warranties.

Lift Shaft Pre-construction • Consider requirement for lifting beam or eyes – Who is responsible for testing, markin and certification?

• will test, mark and certify it?

• If the lift shaft is constructed in blockwork or brick, confirm that minimum wall thickness is correct and without cavity.

• Is scaffolding required or can it be omitted? If required does it meet requirements.

• Consider requirement for beneficial use and plan for cost, programme and final test.

• Understand the pre-construction programme and ensure required notices are given and the site is ready. If the lift installers go elsewhere they might not be available again for weeks!!

• Consider interface requirements with BMS and fire alarm.

• Is there an opportunity to drill the lift shaft walls as opposed to providing inserts?

Page 148

Avoiding Defects - Revision D – July 2013

Construction • Ensure that fallgate is erected with the frame and system has been agreed with lift contractor. (Red Top) • Have all open entrances been made safe?

• Is the lift shaft fully constructed in accordance with the latest revision of the approved lay out drawing?

• If blockwork or brick have been used, confirm that construction at top of shaft is in line with lay out drawing. Ledges are not allowed.

• Confirm that any pad stones have been poured in situ using good quality concrete and are tied into the brickwork.

• Is there any sign of dampness, water or rubble in the pit? If so reject handover of liftshaft until fixed.

• Are all entrance lintels at the correct height?

• Does the lintel at the top floor extend across the whole shaft and is it securely attached to the side walls (Mandatory for use of Otis Access Platform).

• Have the front walls been left down to lintel height at the agreed access floor?

• Have all thresholds been constructed to correct height below FFL? • Are all the front returns and rough openings as per the lay out drawing? (Top floor is bigger for E&I panel, check offset).

• Are all recesses correctly formed for each entrance if required?

• Are all inserts correctly positioned and cleaned out of infill material.

• Are fixing bolts available on site? Is drill and fix solution suitable?

• Ensure that the lift shaft is clean and painted throughout? (If required this can be by lift s/c).

white

• Are there any services in the lift shaft not directly associated with the lift installation?

• Is ventilation provided at the top of shaft as per lay out drawing?

• Are all FFL datum lines clearly marked inside the lift shaft?

Avoiding Defects - Revision D – July 2013

Page 149

• If the lift is set up to grid lines, have these been identified and clearly and permanently marked in the lift shaft?

• Ensure that 2 no. 35mm diameter holes are provided above the top floor lintel for use of Life lines?

• Has a 110 volt power supply been provided adjacent to the top floor entrance?

• Ensure that all holes required in front walls for landing fixtures are present.

• Permanent shaft lights and pit socket are required. Can these be included in the lift subcontractors package?

Reference documents: Temporary Lift Shaft Gates - RED TOP

Page 150

Avoiding Defects - Revision D – July 2013

44.0

Utilities

The following information needs to be considered irrespective of whether the utilities are providing supplies for either a client end user needs or site requirements during construction operations.

• Ensure that there is available on site a detailed survey and drawings of all existing services.

• If existing records are suspect in any way instigate geophysical mapping or other methods of buried services location.

• Under no circumstances should the ground be penetrated without suitable records being available.

• Keep detailed records of all negotiations with utility companies.

Electricity (MV–Medium Voltage LV – Low Voltage) • Ensure clients maximum demands have been interpreted correctly (ensure we have allowed for any specified spare capacity).

• Involve local Regional Electricity Co (REC) early in the design process.

• Involve the REC in regular design and progress meetings.

• Ensure coordination meetings are carried out to ensure existing services or proposed services i.e. drainage / manholes etc do not impede the installation.

• With new utilities make allowance for payment up front. Some of these costs can be very substantial and encompass services upgrade / enhancement of networks to support the client’s load needs relative network capacity.

• Internal substations must be built in accordance with the REC specification. The substation may also need to be compliant with other specifications such as fire rating. A fire rating of 4hours for the internal walls and roof/ceiling could be required.

• Allow approximately 6 months to build a dedicated substation from placement and payment of order.

- 12 weeks for procurement of material - 12 weeks for the fit out of the sub.

• Obtaining a quotation for a new substation may take 8 weeks.

• Ensure that progress on wayleave agreement is chased regularly. (when required) Avoiding Defects - Revision D – July 2013

Page 151

• Obtaining a wayleave could take 20 or more weeks from signed order.

• Make the application for meeting early along with the selection of shipper. Beware though, if an existing consumer already in contract with a shipper, may change services provider(s) midway through negotiations. If the client / end user is responsible for completing the agreement this could take considerable time.

• Identify method of and type of metering to be employed for scheme and determine tariffs.

• Flat level access will be required for delivery of transformer and switchgear.

• Internal substations may need incorporating into the main fire alarm system.

• Using aspiration systems for substations may alleviate the need for conventional fire detection devices.

• Internal sub-stations may also need incorporating into the Clients buildings intruder alarm and access control systems.

• Where 24/7/365 access is required then access to the substation through any external security roadway vehicle /pedestrian control barriers and or gates needs to be considered.. This is especially likely where the building is closed overnight / weekends and holiday periods as REC engineers may need to attend at any time without notice to carry out switching operations affecting other REC users etc.

The interactions may require special lockable covers on an additional specific access control switches/card readers for their sole use and the facility to permit the fitting of REC special padlocks.

• The access control system where REC access is required may also be an issue if they have sub-stations constructed within the grounds of the clients premises.

• When designing the overall site layout and dedicated REC substations feature, arrange layouts (where possible) such that the REC access can be made without having to pass through a secure boundary line.

• Allocate a dedicated person to have an overview of construction and subsequent snagging of the substation. This person can then organize the third party (REC) inspections and Page 152

Avoiding Defects - Revision D – July 2013

approvals at appropriate stages. If the inspections/ comments are not closed out, energisation may be delayed.

• Substation doors are required to open outwards a full 180° and be secured in this position. Consider if this works with louvre and façade design. Consideration is especially important if the doors open directly out onto the public highway / footpaths etc.

• Aim to ensure that all building elements are fully completed prior to energisation. Once energised, access into the sub will be severely restricted, full method statement and risk assessments will be required along with a dedicated representative from the REC for any future access, this will also be chargeable.

• Client MV sub stations require constructing in accordance with the REC specification and may be subject to planning restrictions.

• MV substations must be snagged appropriately.

• Once an MV substation is energised access will be restricted to personnel with the appropriate HV awareness training, this representative will be required to complete permits to works along with risk and method statements for any future access into the sub-station.

• During contract discussions with the electrical contractor, identify how they will be controlling this access and who will be carrying out MV switching operations (in house personnel or brought in as required). Who will do emergency switching to restore power etc. together with routine switching if forming part of a large private network, for instance).

• Ensure the end user is aware of their obligations regarding access to the MV sub station. This may be restricted to REC personnel, however end user access may feature if the MV substation(s) form part of a private MV network around a site with multiple buildings and fed from a primary MV REC network supply i.e. large factory /office complexes.

• If substations are installed with combined MV/LV Switch rooms then authorised personnel with MV training / knowledge will be required.

• Where possible it is recommended that to alleviate access issues that MV switchgear and transformers are separated from LV equipment by caging off the MV voltage area/components.

Separate housings and special lock out provisions can then be utilised.

Avoiding Defects - Revision D – July 2013

Page 153

• Note that incoming supplies will only be energised if in a secure watertight environment. This requirement needs consideration when planning construction phasing.

Telecommunications • Involve the telecommunications provider early in the design process as some of the resultant costs can be substantial and encompass services upgrade / enhancement of networks to support the clients communication needs relative to networks capacity.

• Clarify early who is responsible for installing lines from the main Open Reach termination point within the building to lifts, BMS, server room etc.

• Most telecommunication company will provide a design planner for the installation.

• Ensure wayleave agreements and planning permissions are regularly chased. This could take up to 20 or more weeks to finalise once order signed and legal duties are established.

• Ensure adequate telephone lines are ordered at an early stage and include all lines such as BMS, Red Care for fire & security, lifts etc. as well as those required for general use.

• Each lift will require a dedicated direct dial telephone line for outside communication (PABX lines cannot be used for this aspect).

• Telephone lines may also be required for utilities metering (electric and gas) as auto billing purposes is preferred. The utilities may utilise SIM card wireless communication which they will provide.

• In some conditions the utllity wireless systems can’t communicate, with the result that dedicated phone lines will be required, service providers will install these telephone lines at their cost, but will require facilities access through the buildings /grounds that share incoming communications to install them.

• Materials for the external installation are generally provided free for connection to the network.

• Ensure the service ducts are installed in the correct colour to suit the incoming telecommunication and data providers. In most cases they require their own dedicated coloured duct system together with dedicated cable chambers. This applies Page 154

Avoiding Defects - Revision D – July 2013

irrespective of where the communication lines are needed i.e.

Clients networks or even temporary site temporary lines.

• Contact the ‘dial before you dig’ service to obtain network plans for the construction area. (0800 9173993).

Gas • Involve the regional gas company as early as possible.

• Establish as early as possible location of gas supply entry point onto site and into building and also location of main gas meter and any sub meters.

• Establish type of supply and whether a pressure reduction governor station will be needed.

• The utility company may require a dedicated external building to house equipment with 24/7/365 access? This may have planning implications.

• Is there a requirement to pick up a BMS output from the Gas meter, if so has electrical ducting been allowed for to the meter from the BMS panel?

• Money may be required upfront for work and services. Some of these costs can be very substantial and encompass services upgrade / enhancement of networks to support the clients load needs.

• Regularly chase progress on wayleave agreements and planning permissions. This could take up to 20 or more weeks to finalise once order signed and legal duties are established.

• On rare occasions gas boosters may be required depending on proximity of gas appliance to incoming main. Check availability of required pressures and volumes.

• Is the ground contaminated in any way? If so the Protectaline type of pipework will be needed.

• Make sure that the site installed gas distribution pipework has been sized to afford the correct capacity for the equipment being installed.

• Incoming gas meter is supplied by the gas shipper.

• Seek details of the clients preferred shipper from the client. Be aware that this information could change prior to final meter install if the client(s) seek to take advantage of better terms.

Once a gas shipping contract is placed it they become tied for 12 months in most cases.

Avoiding Defects - Revision D – July 2013

Page 155

Water • Involve the regional water company as early as possible.

• Understand available water pressure as upgrades to infrastructure may be required. Some of these costs involved can be substantial as they may encompass services upgrade / enhancement of networks to support the clients load needs.

• Is there a requirement to pick up a BMS input from the water meter, if so has electrical ducting been allowed for to the meter from the panel?

• If there is a requirement for a BMS input there may be an additional cost from the regional water company for the addition of metering pulse device as not all meters come with this component preinstalled.

• Money may be required up front for survey and connection work.

• Clarify the standard of check valve or protection required from the regional water company’s water distribution network criteria.

• Is the ground contaminated in any way? If so Protectaline type of pipework will be needed.

• Trench inspections will be required from the water authority for the region where the works are being installed, both before and after laying of pipes and prior to permission from them being given to allow back fill of service trench(s).

• Ensure correct service colours have been selected for the water supply pipework and services marker tapes – there are differences between Potable water and others such as grey water for instance.

• The minimum requirement for buried pipe depths in most cases is 750mm from finished ground level to the top of the service pipes. If this cannot be achieved electric trace heating of the pipework will/may be required to prevent frost damage.

• Does the supply need chlorination (stab ins required)? Some water authorities require all incoming supplies to be chlorinated.

• Are two supplies required (mains and fire hydrant/ sprinklers multiple buildings etc)? If so, then each incoming service type may now require to be individually metered. Check water supply company requirements as regions may differ in their policies.

Page 156

Avoiding Defects - Revision D – July 2013

• If fire hydrant main and/or sprinkler systemis to come off mains supply then pressure and volume capacity need to be assessed, storage tank and pumps may be required.

• Regional water companies may want to see domestic water schematics as part of the application for a water supply to enable them to size the supply pipe and metering requirements.

• Water supply may be delayed until installation has been inspected to confirm water authority requirements have been incorporated. This is especially likely when water recycling such as rainwater/grey water harvesting has been incorporated.

Avoiding Defects - Revision D – July 2013

Page 157

45.0

Mechanical Services

• Will building elements meet the design life of the building?

• Consider whether pre-fabricated or traditional installation; plant; risers; horizontal services.

services

• Consider early deliveries of Plant-skids & pre-fabricated plantrooms in advance of some structural/roofing elements; provision of partial water-tight logistics; lift & shift requirements; structural capability to lift & shift.

• Identify Heat-on date(s).

• Review requirements for double walled tanks versus single walled tanks. Are these a single prefab tank or panelled tank for in-situ construction?

• Identify wet areas in plant rooms Consider localised bunding & water-proofing or full plant-room tanking.

• Consider co-location of wet plant to reduce extent of wet area treatments.

• Under-floor heating systems must be fully commissioned prior to floor finish installation.

• Review access & maintenance requirements, step-overs, platforms etc. Consider early/concurrent provision of permanent installations to eliminate temporary needs.

• Review Sequence of installation in internal plant rooms.

Generally the sequence would be - Early delivery of skids/AHU’s; - High level installations; - Plant installations; - low level installations.

However roof plant installations will probably require - Plant delivery/location; - Low level installations; - High level installations.

• When considering luvre/plenum interface, It is preferable to work away from louvres in advance of large plant installation because of working space requirements to construct plenums.

• Consider procuring GRP gratings for risers in lieu of metal gratings.

• Ensure perimeter edge rebates are formed around the openings at every level to allow pre-fabricated riser gratings to Page 158

Avoiding Defects - Revision D – July 2013

be placed in the hole immediately upon construction. This negates the need for handrails or edge protection.

• Review whether it is a benefit to install all underground pipework at an early stage of the project.

• Ensure all required plinths are detailed on construction drawings and set out by the structural & MEP engineer.

• Consider instructing the coordinated drawing subcontractor to produce fully dimensioned BWIC drawings for all slabs, partitions & blockwork walls and roofs.

• Place utility orders early and get gas & water connected and under control as soon as possible.

• Ensure specialist plant and M & E contractors carrying out bracket design submit their designs / calculations early in order to ensure that these are approved by the Structural Engineer.

This should include the worst case loadings of what is being supported, proposed fixings and type of unistrut to use (including manufacturer’s data sheets) etc.

• Hold design & buildability reviews weekly. Cover all M&E Consultant drawings, Subcontractor drawings, and all other Architectural drawings which have an interface with M&E i.e. ceilings, sanitaryware etc.

• When filling the LTHW systems, ensure they are dosed and left full with biocide inhibited water to avoid flash rust.

• On healthcare projects, check the domestic pipework specifications as flexible connections may be prohibited and hard piping to all outlets is likely to be required.

Trench Heating • Determine area where trench heating is required. – Is the trench heater for heating only or is cooling also required?

• Confirm whether trench heater is a 2 pipe or 4 pipe arrangement. (Heating and cooling units only).

• Determine dimensions of trench heater (depth, width & length) to suit surrounding. (i.e. raised floor, between columns).

• Review the power and BMS signal requirements for fan assisted trench heaters.

• Check whether a condensate tray is required for cooling features. This will be dependant on CHW flow & return temperatures.

Avoiding Defects - Revision D – July 2013

Page 159

• If long trenches (>5 metres) are being heated review whether the heater elements are continuous or in multiple sections. (dependent on length of units, logistics considerations) If there are multiple sections confirm whether pipe connections between elements are internal or external.

• Are trench heating internals easily replacement/maintenance if necessary.

removable

for

• Are pipe connections left hand side or right hand side.

• Review which valves/accessories are supplied with the trench heaters. Are the control valves to be supplied by BMS or trench heater supplier?

• Confirm compatibility between trench heating and BMS system.

• Review whether trench heating dummy grilles are required?

Architect to advise on aesthetics.

• Confirm trench heater structure is robust (Does not flex once weight is on unit, packing might be required.) once mounting feet are positioned and levelled.

• Ensure ply protection or similar is bought to protect grilles from damage (fins are easily bent / damaged).

• Easi-edge sockets need to be ground flush with the slab prior to installing trench heating brackets.

• Check to ensure concrete slab is within tolerance.

• Carefully consider setting out methodology e.g. interfaces with curtain walling & raised access flooring.

• Obtain cleaning / maintenance regime from manufacturer and include in the O & M manuals as heating elements attract dust.

• The trench heating grille should be flush with window grille if present. Has allowance been made for carpet tiles? What thickness?

• Avoid gaps between trench heating units and the surrounds.

• Trench heating units should not have excessive movements when units are stood on.

• If underfloor pipework is being used it should not rise to trench heating elements. If this is unavoidable then air vents should be used.

• Has producing a mock up for agreement / signoff by the architect/client/consultant been considered?

Page 160

Avoiding Defects - Revision D – July 2013

Mechanical Installation • Ensure that all exposed pipework ends are capped off while being installed to prevent foreign objects being lodged in pipes by others creating a blockage.

• Check pipework bracketry designs to ensure there are no clashes with the building fabric such as 1) pipework support bracketry in risers • 2) pipework bracketry to be concealed within column voids etc.

• Check that pipework brackets are installed at the correct centres (per manufacturer's data sheets).

• Ensure that pipework (e.g. condensate) is installed to the correct falls.

• Has pipework expansion been considered and installed?

• Have fire sleeves been considered and installed?

• Has crimped pipework been used? (BLUE TOP) • All pumps vibrate and must have suitable flexible connections.

• Make sure inertia bases are properly designed and constructed of the correct concrete mix.

• Ensure that inertia bases have properly cured.

• All copper pipework should be free from oxidation (greening).

• Pressure testing for pipework should be to specified values static head needs to be taken into account.

• Can control valves be flushed through or should stool pieces be installed?

• Check all valves have been installed in the correct flow direction.

• Is the installed pipework the correct pressure ratings.

• Are all open vents suitable covered?

• Cuts in pipework must be square to the axis of the pipe with burrs / irregularities removed.

• Has enough distance installation of lagging?

between

pipes

been

allowed

for

• Low points in popework must be fitted with drain cocks.

• All high points should have air vents - check if specification allows automatic air vents.

Avoiding Defects - Revision D – July 2013

Page 161

• If pipework is to be fitted with trace heating, supports should be electrically isolated from the pipework.

• Chilled water pipework supports should ensure continuity of the vapour seal and blocks should be used between pipework supports and pipe.

• Painted pipe must be chip free on handover. Touch ups should be colour matched.

• Gas pipework must conform to Building control requirements – Confirm whether flanged joints are allowed or is welding required?

• Have valves been installed in compliance with manufacturers recommended distances?

• Can all valves be supplied by the same manufacturer?

• Have flexible connections to terminal units been allowed and/or used?

• Ensure that gauges are the specified size and range.

• Are condense pumps allowed - if not does condensate pipework have correct falls?

• Ensure that waste pipes have the correct falls.

• Drainage must have adequate access for rodding.

• Consider power systemisers.

requirements

to

sanitary

controls

e.g.

Building Management System • Start a 'BMS File' early. manufacturer's data sheets.

Include

all

relevant

plant

• Success with the BMS is heavily dependant on procurement so issue a copy of the BMS file to the BMS contractor at enquiry stage i.e. prior to placing the order.

• Interrogate that the specification and the functions required are fully understood.

• Interface points between suppliers and BMS contractor should be resolved early to allow correct panel manufacture.

• Has a fireman’s override switch been specified, if so consider what plant it should control.

• Has the Description of operations been agreed and signed off?

Page 162

Avoiding Defects - Revision D – July 2013

• All cable installations to adhere to the required electrical specification.

• Agree sensor and control manufacturers.

• Ensure that control valves are sized to the selected plant and agreed by the consultant.

• Can control valves on pipework be flushed through? Should stool pieces be used prior to flushing?

• Agree graphics and BMS texts early.

• Agree the aesthetics and locations of room thermostats.

• Have sensing methods been specified/ agreed. E.g. differential pressure switches or flow switches.

• Have time and temperature parameters been specified and are these achievable?

• Agree locations and numbers of sockets for pipework sensoring equipment before installation and flushing.

• Have panel visual indicators been agreed and allowed for in panel construction - drawing sign offs.

• Agree alarm indications and actions. - Is there a sounder, text message/email alert required?

• Confirm whether manual reset.

plant

equipment

requires

automatic

or

• Is the plant required to carry out a sequenced shut down on fire alarm signal?

• Source actuators to be from same manufacturer.

• Do actuators have adequate access to allow maintenance and replacement.

Air Conditioning Units • What type of refrigerant is to be used.

• Check Energy Efficiency and Specific Fan Power (SFP) in accordance with Building Regulations Part L 2013.

• Have type of air conditioning units been specified? (VRF, DX, Wall mounted, ceiling mounted etc).

• Has the location of internal unit agreed?

• Ensure that wall finishes are complete prior to the installation of internal unit.

Avoiding Defects - Revision D – July 2013

Page 163

• Be aware that the external unit has to be installed within a certain distance of internal unit. Confirm if this is possible and has location been agreed?

• Review power requirements for both units as manufacturers stated requirements do not always cover them both.

• If pipework is to be exposed is it to be painted?

• Check that condensate pipework has the correct fall, or is a condensate pump to be used.

• Wall penetrations of pipework must be fire sealed.

• Consider if the units are to be alarmed or monitored via the BMS? Are there sufficient inputs available for this? Consider including air conditioning unit and condensate pump faults.

• Is air conditioning unit controller to be remote or wall mounted?

Water Heaters • Are the units to be pre-insulated?

• Review specifications - is hot water system to be electric or gas, vented or un-vented?

• Has expansion in the Hot water system been addressed? i.e. expansion vessel sizes, safety valves, bellow, anchors and guides. Has all of the above been signed off by the consultant?

• If the units are integral and have their own controls, do these interface with the BMS? These must be agreed with the controls company.

• Installation must comply with legionella legislation.

• All pipework connections specification/section.

to

comply

with

pipework

• All flue connections should be damage free.

• Is a dilution fan required?

• Are ventilation requirements for the heaters met?

Boilers • Check specification and arrangement requirements. Consider what the design temperature of the heating is and are boilers to run duty/standby.

• The safety valves for the boilers need to be designed and set at the correct pressures for safe operation.

Page 164

Avoiding Defects - Revision D – July 2013

• Confirm that the safety valve and discharge pipework been installed correctly? Position/length of run/size?

• Do the noise specification?

requirements

for

the

boilers

meet

the

• Have the ventilation requirements been met.

• Before commissioning boiler ensure that the requirements for this stage have been met. - gas purge, heat load, flushed LTHW system.

• Check whether factory tests are required. Is this per boiler or for type?

• Are flue gas analysis tests required?

Biomass Boilers • Is the project in a clean air act area? If so the boiler will be required to be clean air exempt. Further information can be found at http://smokecontrol.defra.gov.uk • Is the project part of the renewable heat incentive?

• Is there a requirement for a heat meter?

• Has the Kier Biomass boiler safety alert been reviewed and considered? (REDTOP) • Has the HSE Biomass store safety report been reviewed and implemented in the design? E.g. Asphyxiation on entry into biomass stores.

• Who is responsible for supplying the commissioning fuel?

• Ensure that the proposed fuel both for commissioning and by future client is as per the manufacturer’s specification. Ensure certification is available from suppliers.

• What is the proposed fuel type? Is the Boiler, fuel store and fuel delivery equipment compatible?

• Does the heating system require a duffer vessel?

• Have controls been considered, does the biomass boiler come with its own control panel?

• Who is responsible for wiring the biomass boiler, is it part of the boiler package or a recommended subcontractor?

• Biomass boilers are extremely heavy. Have logistics/lifting been considered, • Consider weight restrictions in plant areas.

Avoiding Defects - Revision D – July 2013

Page 165

• Have maintenance requirements been considered?

Maintenance can be much more intensive compared to a Gas boiler. Auto cleaning boilers are available.

• Has provision for auger burn back protection been considered?

• Is a Biomass fuel store level indicator required?

• Has vehicular access to the fuel store been considered for fuel delivery?

• Has the means of fuel delivery been agreed? Some methods may be noisy i.e. blown deliveries can be up to 90dB. • Has the design of the fuel store been reviewed in terms of access and maintenance etc.

• Have Silo’s been considered as an alternative to brick built stores?

• Has planning of Flue design/heights been approved?

• Consider whether a licence is required to commission/ operate?

• Check that there are no unsealed gaps/joins in the external auger, Moisture ingress to the wood fuel will expand and solidify the fuel preventing the screw from turning.

Boiler Flues • Is the flue in a coastal environment? If so up- rated materials may be appropriate to prevent corrosion etc.

• Is attenuation required?

• Is boiler unit to be fuelled by Biomass? Biomass flue design is different from that of conventional gas boilers.

• Is the flue designer/installer gas safe registered?

• Review who is providing weathering for flue penetrations. Is the proposed method adequate?

• Flues are normally supplied unprotected by the manufacturer so consider sequencing and protection from adjacent trade to avoid damage.

• Condensation pipework installed at base of flues is to be in line with pipework specifications.

• Do external flues have to be colour matched to elevations or roof?

• Boiler flues that extend above the roofline require that planning approval is obtained.

Page 166

Avoiding Defects - Revision D – July 2013

• Review the flue arrangement required (Common or dedicated) compare with boiler manufacturer’s specifications and resolve any differences.

• Is a flue dilution fan to be used?

• Flues are to be handed over free from damage or marks.

• Has the structural design allowed for the support of the flue?

• Is lightning protection required and has this been allowed for?

• Does the flue penetrate a fire compartment? If so, fire stopping will be required.

• Is there a requirement for dispersion modelling to be carried out?

• If dispersion modeling is required then early input from boiler manufacturers regarding emissions (in correct units) and involvement of the Environmental Agency is required.

• Clarify any requirements procurement stage.

for

a

staged

installation

at

• The flue design needs to be included in the co-ordinated services design especially in energy centres.

Radiators • Ensure that radiators are installed in the correct design configuration or there may be heat transfer issues.

• Review radiator schedule against the layout drawings to ensure correct size and type of radiator has been fitted.

• Check radiator is level and all brackets are present and secure.

• Check correct type of valves have been installed.

• Check air vent and cap have been installed securely.

• Check that the radiator is damage free.

• All radiators must be commissioned.

• Turn the radiator valves once per month or so to prevent the inner pin 'sticking'.

Sprinklers • Sprinkler head phials should be free from any contamination particularly fire spray.

Avoiding Defects - Revision D – July 2013

Page 167

• Caps should be kept on sprinkler heads at all times as these are easily damaged & may be contaminated (e.g. by airborne paints, dust etc) • Has the fire strategy and sprinkler coverage been agreed (client/fire officer/building control and insurer) particularly cut off heads and non-fit out areas. Consider also permanent non-

protected areas, OH classifications, Duty/standby pump set up.

• What is specified for the sprinklers? Is this hard piped or flexible connections?

• Have the sprinkler specifications been agreed by the insurer?

• Are there any derivations from the LPC guidelines and have these been agreed and accepted by the client and building control and the insurer?

• Flexible connections where used must free from kinks and have an acceptable radius on bends.

• Guides supplied with the flexible connections should be checked carefully as they can hide kinks.

• The sprinkler tank must be sized to hold a specified volume. If the volume is not specified get design volume from designers.

• Sprinkler tank is to be clean and free from defect.

• If the tank is to be split then ensure that access is adequate.

• Are tank warning pipes in visible locations?

• Have tank overflows been piped to drain?

• Review power feed arrangements for fire pumps both duty and standby. Are these fed from essential boards/generator?

• Can both pumps be powered at same time? Does the generator need to be sized for both pumps?

• Ensure that dry riser pressure test is carried out at correct pressures.

• Ensure that the landing valve installation within dry riser box is to British Standards.

• Does dry riser box need to be a designated fire compartment or is riser separated at each floor level?

• Cut outs for sprinkler heads should be as per sprinkler installer requirements which are not necessarily same size as head • Consider producing and agreeing a mock up.

Page 168

Avoiding Defects - Revision D – July 2013

• Is a double check valve required on incoming main and does this require chlorinating.

• Early availability of a dry riser is ideal for fire safety.

• Has the capacity of the incoming water main been checked and verified? This should be done before the sprinkler tank is sized.

• Is the installation to be incorporated into a ceiling with acoustic baffles? As a guide sprinklers should be installed at least 200mm away from any obstruction providing the bottom edge of the object is level with the sprinkler.

• Consider requesting the sprinkler installation to be prefabricated as this improves site cleanliness and productivity.

• Ensure all drawings / specifications are approved by the appropriate person i.e. fire officer/BCO/building insurer.

• Building insurers may wish to inspect the installation at various stages. Ensure their requirements are identified and then met and that after any inspection they issue a report with their findings.

Smoke Ventilation • Are the requirements and strategy in the event of fire properly understood?

• Are smoke dampers fire rated in line with the fire strategy?

• All fans must be to the correct temperature rating for the correct length of time.

• Impulse / cyclone fans should be installed away from air path obstructions.

• Consider Fire stopping to fan housing, particularly round attenuators if present.

• All cables to be to the correct fire rating.

• Are motorised dampers being utilised? Has extraction sequence been agreed?

• Is finger/vermin protection required on motorised dampers?

• Check that supporting unistrut and drop rods are trimmed back and free from sharp edges.

• Is the system to be linked to the fire alarm?

• Consider power /fire alarm interface with smoke vents.

• Agree the automatic opening air vent override switch locations.

Avoiding Defects - Revision D – July 2013

Page 169

• Is a smoke test demonstration required by fire officer?

• Are smoke shafts to be pressure tested?

• Ensure that ductwork used is pressure tested and fire rated to the correct values.

• Ensure no other services are located in the smoke shaft.

• Whenever possible ensure that the shaft is constructed in a manner that is not easily accessible such as an access hatch to avoid change of use i.e. adhoc store.

• Ensure that F&S dampers/damper motors are maintainable from the front of the unit.

Attenuators • Do the attenuators meet the specific noise reduction requirements across the whole sound pressure spectrum.

• Do they meet the pressure requirements - this should include any ductwork arrangement if attenuators are not duct size.

• Attenuators must be defect free, mastic should only be used to seal baffles into unit not for fixing units together.

• Lifting should not be through attenuator as this can lead to baffles being pulled off frame.

• Ensure early supplier involvement for sizes to be fed into coordinated services design.

• Air Handling Plant attenuators to be fitted as close to air handling plant as possible.

Ductwork • Has the ductwork design been cross referenced with the fire strategy to ensure all fire dampers have been allowed for at the correct ratings?

• Has the correct type of fire damper been allowed for in the relevant wall? i.e. Blockwork, Plasterboard or curtain?

• Check contract specifications are flexible connections allowed to FCUs? • Flexible connections to FCU's to be kept as short as possible.

• Check co-ordinated drawings & resolve clashes where possible prior to installation e.g. with ceiling/ other services • Have cut outs for riser mesh been co-ordinated? Who is responsible for providing temporary coverings / ply boarding?

Page 170

Avoiding Defects - Revision D – July 2013

• Review programme logistics. Can all plant room ductwork be craned into position or will some smaller sections need to be made to fit in the hoist?

• What standard of cleanliness is required under the contract, i.e. will specialist cleaning be required? Consider quantity & location of access hatches - are they accessible for maintenance / cleaning?

• Ensure that all ductwork passing over internal walls is fitted with a fire damper to prevent the spread of fire.

• Make sure there is a means of access to the fire dampers so that they can be re-set.

• Make sure smoke dampers have the correct temperature rating or they could melt.

• When using fire rated ductwork, ensure all brackets and flexible connections are also fire rated.

• Bracketry design for ductwork must be at the specified distances and allow for the lagging where required.

• Review whether type of volume control damper is specified.

Otherwise a single manufacturer and type should be selected.

• Volume Control dampers must be installed to manufacturers required distances from ductwork openings.

Grilles and Diffusers • Review if a mock up is proposed / required. Has this been signed off?

• Confirm delivered grilles are to the same manufacturing standard as the signed off mock up.

• If manufacturer cannot get an exact colour match to the specified colour then a sample must be approved.

• Grille installation must be straight and free from any gaps between plasterboard and grille.

• Is a backing plate required on dummy grilles?

• Is the number of blades specified?

• Are blades full length or shortened.

• Grille and blades should be free from scratches - particularly after blades have been set up for air paths.

• Are grilles individually identified and clearly numbered to correspond with drawings and schedules.

Avoiding Defects - Revision D – July 2013

Page 171

• Are they individually wrapped and protected against damage?

• Consider delivery strategy. Are these to be stored (where?) or delivered “just in time” for installation.

Air Handling Unit • Consider requirements for craneage / contract lifts etc.

• Who is responsible for the assembly of the AHU’s if sectional or modular?

• Who is responsible for wiring the AHU’s if modular and use manufacturers controls?

• Has a redundancy study been carried out on the unit selections?

• Is Factory testing required and what is the requirements? Each type of unit, one single unit? In mock up on site or factory mock up?

• Do the units meet the following specified parameters - external pressures - filter grades - flow rates, based on correct flow and return temperatures.

• Have glass traps been specified and how are these to be protected.

• All units must be clearly and uniquely labeled.

• Check that all doors are correctly installed and sealed on site.

• Review whether the AHU is to be pressure tested in-situ.

Fan Coil Units • Consider the types of Fan Coil Units - horizontal or vertical mounted unit and location of unit - ceiling void mounted, floor void or wall unit.

• Building Regulations Part L 2010 state that Fan Coil units have a maximum of SFP of 0.6W/L/s. (Note: Part L 2013, Fans SFP to be max 0.3W/L/s.)

• Ensure EC High Efficiency Motors utilised to meet Specific Fan Power (SFP) values. (Note: AC motors are to be phased out.)

• Check whether the BMS package includes free issue controllers, control valves including compression nut and olives, actuators and return air sensors as these will need to be fitted at factory.

Page 172

Avoiding Defects - Revision D – July 2013

• Check whether Fan Coil Unit plenum (acoustic lined) required for discharge or intake or both?

• Confirm power installation – Fan Coil Units comes with fly lead.

• Check whether a transformer is required for controller and fan enable signal.

• Confirm handing of Fan Coil Unit is correct.

• Confirm that blanking plates for unused spigot connections have been included.

• Check a selection of delivered fan coil units against specification - particularly noise requirements, flow return temperatures, speed settings and pressures.

• Is Factory testing required and what is the requirements? Each type of unit, one single unit? In mock up on site or factory mock up?

• Filter requirements and grade need to be in accordance with the specification.

• Review how much flexible pipework is allowed in the Secondary ductwork from fan coil units.

• All fan coil units should be clear and individually referenced with markings clearly visible on unit.

• The alignment and distance of fresh air inlet to the back of the unit must be within specified tolerances.

• Consider whether the filters need cleaning or replacing prior to handover?

• Ensure sufficient space has been allowed for around LTHW and CHW pipework to allow insulation to be installed.

• Are units installed level as the condensate needs to run to a fall.

• Check noise criteria with location of fan coil units.

• Has a redundancy study been carried out on the unit selections?

• Have ductwork system resistance checks been carried out following coordinated drawings?

Fans • Fans selected must be of the correct type - axial/centrifugal.

• All fans should be from one manufacturer.

Avoiding Defects - Revision D – July 2013

Page 173

• Select fans to match the specified flow rate and pressure ratings.

• Has a redundancy study been carried out?

• Consider whether fans require a BMS fault status connection?

• Have ductwork system resistance checks been carried out following coordinated drawings?

• Clarify how Duty / Standby units change duties. Is this automatic / manual or through the BMS? • All installed fans should be free from damaged, clearly and uniquely labeled.

• All bracketry and drop rods must be trimmed and free from sharp edges.

• Variable speed provisions and requirements should be clarified with the fan manufacturer.

• Installed fans must meet specified noise requirements.

• Do fans installed in fire walls require integral fire dampers?

• All openings surrounding wall fans must be made good before handover.

• Ensure the responsibility for the control of the fans is understood and bought in the correct subcontract package i.e.

BMS, PIRs, Lighting Circuits, Speed Control etc.

• Review allowances in package for wiring the fans to the power supplies and controllers?

• Make sure the handing of the fan is correct and as per the coordinated drawings.

• Flexes should be bought with the Fan purchase order.

• For kitchen extract fans; ensure that these have been designed with the pressure drop of the extract canopy and volume flow rate requirements in mind.

• Review whether kitchen extract fans need to be fire rated?

• Are inverters required for the fans? What package are these being bought in? Fan purchase order or BMS? • Are any extended warranties required following delivery and installation of the units?

• Make sure the AV mounts and mounting feet are bought with the fans.

Page 174

Avoiding Defects - Revision D – July 2013

• Condensate pumps will be required if installing heat recovery units. Consider responsibility for installing these as they are normally supplied loose?

• M&E Consultant approval must be sought prior to procuring from the proposed fan manufacturer.

Pumps / Booster Sets • Has a redundancy study been carried out and a schedule been produced?

• Understand pump duties and spare capacity –highlight any deficiencies.

• Do the flow rates on the schematics match the schedules?

• Ensure all valves/pipework/fittings etc. meet the pressure drop requirements in the specification as this may affect the pressure on the system.

• Is there sufficient access for maintenance of motors etc?

• Confirm that pumps are the correct type and selected with the correct flow rate and pressure requirements.

• Pipework connections to pumps should be flexible.

• Pumps should be free from damage, installed square to pipework and to the inertia bases.

• Inertia base springs under loading should compress equally and vertical on all four corners.

• Pumps should be clearly and uniquely labelled.

• Booster sets should be installed to manufacturers requirements - often on concrete plinth.

Chillers • Has the pipework arrangement through the chillers been agreed with the chiller manufacturer?

• Have the chiller air flow requirements been met?

• Do chillers need to raised off the ground?

• Chillers are to be free from damage - fins and coils are particularly fragile, protection should be provided.

• Check whether factory tests are required. Is this per chiller or for type?

• Do chillers meet noise specifications, internally and external to the building.

Avoiding Defects - Revision D – July 2013

Page 175

• Consider impact of weight restrictions in plant areas.

• Consider crane type for location and contract lifts etc.

• Have the maintenance access dimensions around the chiller (normally issued by the manufacturers) been adhered to.

• Consider the wet load of the product when determining working structural load (especially if you are using an air cooler on a roof).

• Ensure the correct anti- vibration mounts recommended by the manufacturer are fitted (normally colour coded).

Insulation of pipework • Ensure that a thin coating of anti-corrosive gel (e.g. Denso paste or equivalent) is applied to copper pipework to prevent 'pinhole corrosion' when using phenolic foam insulation.

Alternatively get a statement from the insulation manufacturer stating that it is unnecessary and that they warrant their product.

• Do not lag any pipework until satisfied with the pipework installation (for example, carry out a height check survey of pipework within the ceiling void - will there be any clashes with the ceiling or other services etc?).

• All services must be labeled to British Standards.

• Check are labels on the right services with flow arrows pointing in the correct direction?

• All lagging is to be free from damage and rips.

• Is aluminum cladding required in plantrooms or other areas?

• Are valve coverings specified? Are they to be box type or bag?

• Chilled water pipework must have a vapour seal maintained across its length.

Underfloor heating • Underfloor heat up/cool down cycle to be as per manufacturers instructions. Guidance must be sought from screed suppliers and floor finishes suppliers/manufacturers as this will differ somewhat from the guidance given by the underfloor heating supplier. In resolving this consideration of warranties is key.

Always seek and comply with recommended temperature ranges from the screed and floor finishes suppliers / manufacturers.

Page 176

Avoiding Defects - Revision D – July 2013

• Has the programming of the heat cycling of the under- floor heating and screed been considered with regard to floor finishes programme? There may be a requirement for temporary boilers to be used if heat on is to occur after the floor finishes.

• If temporary boilers are to be used then ensure that this is controllable to ±2 °C as maintaining the exact temperature requirements is critical to maintaining warranties.

• Consider what controls the underfloor heating? (the BMS or specialist setup) What interfaces are required between the two?

• End users regularly raise issues on the time required to change the temperature. Consider the quickest and most effective way to manage the Underfloor heating controls.

• Are underfloor heating manifold cabinets required?

• If underfloor heating manifold cabinets are required then special consideration must be given to the access and ability to change components within the cabinet. Access may be required urgently so a suitably locked door restricting access to FM teams is preferred over a screwed panel.

• Ensure that other trades are aware of the location of underfloor heating to avoid penetration into the slab and possible rupture of pipework.

• Locate clear and visible signage within the area of the installation and display as-built route drawings if available.

• If the floor finishes are complete then taped up areas clearly showing pipework locations is recommended as generally anyone drilling a floor will do so after the floor finishes are complete.

• Sole boards / scaffold must be removed and not concealed beneath the screed / underfloor heating.

• Check the spacing between pipes is as per the intended design and routes match construction issue drawings as furniture and sanitaryware will use these drawings to co-ordinate.

• Ensure that any joints which will be incorporated within the screed are tested and witnessed prior to screed finishes.

Particular QA inspections should also be given to pipe fixings to ensure that clips are at the correct spacing and fixed securely.

• Confirm responsibility underfloor heating.

for

providing

control

Avoiding Defects - Revision D – July 2013

valves

for

Page 177

• CIBSE and manufacturer’s testing regimes must be adhered to; As a minimum the following tests must be applied.

1.

2.

3.

Flow test – prior to screeding - Installer to prove that a suitable flow rate can be achieved and that circuits are correctly connected to the relevant manifold number, this also proves that no blockages are present.

Air test - prior to screeding - Ensures there are no leaks or damage to pipework , this should be at least 2 X the working pressure of the installation to extend a level of comfort that the final operating pressures will not be an issue .

Hydraulic test which will be completed after the screed has been laid.

Chilled Beams It is planned to add notes on chllled beams in a future edition.

– If you feel you can add to this section please contact one of those mentioned in the back of the book.

Ground Source Heat Pumps • Check the initial design thoroughly (at tender stage) and ensure the separation between boreholes is sufficient and not closer than 8-10m centres.

• Include all ground work activities in this order, CAT scans & underground surveys, setting out of boreholes, drilling, trenching, backfilling & compaction, local fencing etc.

• Carry out a full design comparison against all tenderers.

Compare the following key items: o Average Coefficient of Performance (CoP) o Specific peak heating load (kW) o Heat Pump CoP o Duration of design life o Quantity of boreholes o Depth of boreholes o Total borehole length o Separation between boreholes o Boreholes field area required o Seasonal performance factor (CoP) – worst case, best case, average Page 178

Avoiding Defects - Revision D – July 2013

• Include the electrical installation in the GSHP package.

• Ensure the BMS controls & interfaces are resolved at an early stage.

• Get the external flushing / manifold chamber designed and pre-fab’d for delivery at an early stage.

• Both the external pipework and internal pipework need to be bought in the same package (including the supply & install of all plant).

• Ensure the subcontractor allows for the removal of spoil (including solid & liquid arisings) from borehole drilling operations.

• It is recommended to have a trial borehole carried out to check the feasibility of the ground prior to the system being selected and designed.

• Seasonal commissioning will be required after completion.

• Make sure the company chooses the correct drilling rig (either mud flush or air).

Reference documents: HVCA TR 6 - Good Practice Guide to Site Pressure Testing of Pipework HCVA TR 11 - Good Practice Guide to Use of Plastic Pipework HVCA TR 30 - Good Practice Guide to Heat Pumps HVCA DW 145 - Good Practice Guide for Installation of Fire & Smoke Dampers HVCA Good Practice Guide to Combine Heat & Power ASFP Blue Book Fire Resisting Ductwork to BS13501 Parts 3 & 4 CIBSE Guide E - Fire Safety Engineering CIBSE Technical Memorandum 43, - Fan Coil Units BSRIA NonDomestic Hot Water Heating Systems BSRIA Illustrated Guide to Ventilation BSRIA Illustrated Guide to Mechanical Cooling BSRIA Structural Fixings for Ductwork BRE IP2 10 Ground Source Heat Pumps

Avoiding Defects - Revision D – July 2013

Page 179

Water Storage • Find out from the manufacturer what floor tolerance is required for the tank - can the tank to sit directly on concrete or should steels be installed?

• Procure a pre-installation check visit from manufacturer.

• Consider who is responsible for filling the tank with water.

• Ensure the tank fill is done within 10 days (or as prescribed by the manufacturer) to obtain the manufacturer's warranty.

• Check tank configuration & ensure adequate room height / access for building maintenance.

• Ensure responsibility is identified inspection prior to commissioning.

for

tank

cleaning

and

• Is adequate overflow pipework installed and are falls to drainage gully correct?

• Is a CAT ladder required? Does this require to be 'hooped'?

• Find out what height is acceptable before a hooped ladder is required.

• Beware there are three different methods of stating tank size so make sure useable water volume is correct to specification.

• Overflow pipes require insect/vermin mesh to be fitted.

• Check components are compatible with the chemical makeup of the liquid.

46.0

Electrical Services

Electrical Services • Identify Power-on date(s).

• Identify energisation date(s) from Statutory Authorities.

• Consider temporary power needs – if heat-on is late in process are temporary heat & dehumidification necessary/required?

• Ensure M&E consultant design is coordinated with the project architects’ layouts.

• Hold regular design team meetings to ensure any changes are incorporated.

• Hold regular progress meetings with the electric service sub contractor and record QA / snagging lists.

Page 180

Avoiding Defects - Revision D – July 2013

• Document / drawing control must be kept up to date and reviewed at progress meetings.

• Inform building control of all changes and include in regular meetings.

• Allow for an amount of secondary containment within the electronic services package.

• Allow for a finishing/commissioning manager in the package to ensure snagging and QA are delivered efficiently. If not who is responsible.

• Try to secure direct employed labour and dedicated supervision and avoid subletting.

• Contractor QA activities to include production of ceiling close out forms.

Fire Alarm System • Allow sufficient time in complex projects to agree the cause and effect strategy on a complex project.

• Aim to get involvement early on by all parties including BCO. • Deviations from BS 5839 will need building control approval.

• Establish system monitoring requirements and ensure that a dedicated phone line is ordered along with a system monitoring contract.

• In areas where access hatches are not appropriate consider an aspiration system where only test point access is required.

• Where ceilings and ceiling heights are changed check for excess void depth that may need to protected.

• Currently for voids greater than 800mm, access to void detection will also be required.

• Involve fire alarm representative in scope and procurement meeting for door and door furniture. Where detents are required, these will need to release on the activation on a fire alarm. Also consider mag locks, smoke vent activators).

• Ensure the fire alarm contractors third party connections forms are issued and returned in a timely manner.

• Ensure passenger lift interface connections made early while assistance from list installer still on site.

• Ensure pre commissioning checklists are completed and returned along with delivering commissioning dependencies Avoiding Defects - Revision D – July 2013

Page 181

• Agree device labelling format early.

• Check all devices are labeled clearly and correctly.

• Ensure detection is identified within lift voids and risers.

• Ensure a detector is located within 1m from any lift opening.

• Confirm if the system is to be open protocol early and ensure that the the terms of the open protocol are defined. Do not merely cite industry standards because these differ in interpretation.

• Ensure all mimic panels, smoke damper panels etc are supplied via fire rated cabling from local distribution boards.

• Ensure voids that do not require coverage are identified early and have agreement of the fire officer • Understand the vulnerability of building occupants to sound levels of the fire alarm sounders, NHS HTM’s have clauses for vulnerable people.

• Ensure the system operation is well understood by the client.

• Where panels are reset ensure that for 2 knock systems the search durations are clearly stated and agreed with the fire officer.

• Ensure that the fire alarm detectors are correctly labeled and zoned.

• Understand the type of cabling required, MICC is still referenced in specifications but can generally be replaced with fire rated equivalent.

• Understand the difference between Standard Fire Resisting Cables (Meets PH30 Classification, withstand 830°C for 30 Mins) and Enhanced Fire Resisting Cables.(Meets PH120 Classification, withstand 930°C for 2 hours) • Understand the Categories, (Protection of Property)

L

(Protection

of

Life)

&

P

o L1 – System installed throughout all areas of the building. o L2 - System installed only in defined parts of the building. o L3- 5 – Systems do exist but very rarely used. o P1 - System installed throughout all areas of the building. o P2 - System installed only in defined parts of the building.

Page 182

Avoiding Defects - Revision D – July 2013

• If systems have dual supplies ensure each supply utilises a different route.

• Check specification requirements for spare capacity, is it required on the loops or at the panel?

Reference documents: BS 7671: 2008 Requirements for Electrical Installations lEE Wiring Regulations 17th Edition BS 5839 – Fire Detection and Alarm Systems for Buildings BS EN 54 – Fire Detection and Alarm Systems CCTV System • Ensure that at least two weeks prior to CCTV activation, all parties are notified that CCTV will be in operation.

• Ensure A3 size signs are displayed in prominent locations to advise that CCTV is in operation.

• Ensure CCTV system is coordinated with the project architect.

• Obtain sample recording imagery for the proposed system and seek end user agreement, improvement imagery will reduce the amount of recording time or will require additional storage capacity.

• Obtain location plots for the cameras illustrating depth of field.

• Check that cabling for the CCTV has been bought in passenger lift packages where there is a requirement.

• Consider the use of point of entry CCTV as this will reduce the amount of power supplies required along with access hatches.

Access Control • Ensure M&E architect.

consultant

is

coordinated

with

the

project

• The responsibility for fitting of maglocks is best placed with the joinery contractor with equipment free issued by the electronic services contractor. Samples should be provided for compatibility with the doors.

• Check that the proposed access control system does not impede the emergency evacuation strategy.

• Access control doors will require to release on the activation of a fire alarm.

Avoiding Defects - Revision D – July 2013

Page 183

• Check if client requires any deviation on the release of external access doors for security reasons as this will need building control approval.

• Check access control software (e.g. WINPAK) is compatible with integration Software (e.g. Easytrace).

General • Obtain BCO approval early and involve in any changes to minimise additional requirements at the end of the project.

• Cross coordination meetings should be held with mechanical services contractor.

• Aim to submit O&M manual documentation, drawings and test certificates early.

• Try to secure direct employed labour and dedicated project management and supervision.

• Avoid where possible subletting and ensure approval is obtained where required.

• Snagging lists should be consolidated into a single manageable document.

• Ensure a quick turnaround of contractors RFI’s.

• Aim to rationalise oversized containment where possible.

• Give consideration to over sizing distribution equipment (Say 10%), something always gets added.

• Ensure light fittings are appropriate for the ceiling they are to be installed into and that sufficient depth is allowed above the ceiling.

Reference documents: BS 7671: 2008 Requirements for Electrical Installations lEE Wiring Regulations 17th Edition

Page 184

Avoiding Defects - Revision D – July 2013

Electrical Procurement • Independent M&E coordinated services drawing package should be bought (IME).

• Make sure that secondary containment is bought for each package (BMS, Fire, Data, Security, CCTV, PAVA, Mechanical).

• Buy connections from fused connection units to third party equipment as this is often a gap in scopes.

• When buying FFE any furniture containing power/data (i.e.

Reception desks, Bars, Specialist benching) ensure that there is adequate provision for electrical containment (Dado trunking).

• Consider power for Trace heating, pumps, heaters, solenoid valves, 3rd party panels and CCTV cameras as this is often missed.

• Consider allowing a provisional sum in for additional supplies.

• When buying Lighting allow 10% additional lamps, as lamps will need to be replaced after having given beneficial use of the lighting.

• Electrical contractor involvement is essential with build scope and procurement meetings.

• Multi service containment bracketry should be utilised where possible. However beware of separation requirements e.g. between power and data • QA must be part of the order. Ensure the release of payment is tied to the production of QA such as self snagging QA handovers?

• Buy lighting deliveries on a fully packaged “room by room/Area by area” basis and if possible buy them stored off site to avoid having 00’s of light fittings on site too early.

Electrical Design • Ensure there is early agreement on reflected ceiling plans along with any service hatches that are required for maintainable equipment.

• Ensure maintainable access is provided to smoke and fire dampers (also cleaning hatches, VCD’s etc) and that they are not hindered by containment runs.

• Check for compatibility issues between lighting, dimming and static inverter systems.

Avoiding Defects - Revision D – July 2013

Page 185

• Ensure that Document/Drawing control to be kept up to date and checked at progress meetings.

• Ensure that services structural openings for services are designed in to the drawings early so they can be “built in” and not “retro fitted”.

• Hold regular design team meetings to ensure any changes are incorporated, any changes made should be communicated clearly to all relevant parties.

• Ensure M&E consultant design is coordinated with the project architects/FFE layouts.

• Ensure that combined coordinated services drawings showing all services inc sprinklers are provided (not just single service drawings).

• Consider instructing the coordinated drawing subcontractor to produce fully dimensioned BWIC drawings for all slabs, partitions & blockwork walls and roofs.

• Combined service drawing to show ductwork access point to avoid obstructing them (cleaning point, inspection hatches, fire dampers, VCD dampers etc.

• Ensure Power and data containment have adequate segregation/screening, particularly in service risers, DB Cupboards etc.

• Check data containment is sufficient in size for the numbers of cables (both primary and secondary containment) and has the appropriate bends (swept large radius).

• Check previous projects final account VO’s to help ensure that nothing is missed.

• Establish IT earthing requirements early.

• Ensure that each mechanical system (inc BMS) including scopes, location and power requirements is understood.

• Overlay FFE layouts onto small power drawings to help coordinate setting out and understand the end use of the area.

• FFE heavy areas would benefit from Architects elevations dimensioned to show heights/positions.

• If using lighting control or emergency monitoring consider buying installation drawings from the lighting manufacturer to help simplify installation and minimise risk or reworks.

Page 186

Avoiding Defects - Revision D – July 2013

• Hold workshop meetings for spaces with multiple services to ensure a properly coordinated sequence with buy-in from all subcontractors.

• Obtain electric services design information as early as possible to ensure sufficient power and secondary containment is correctly located to meet requirements.

• Gain agreement on electrical accessory heights as consultants specifications are generally copied from previous projects.

• Architects elevations should be sought for areas heavy in FFE or with critical setting out requirements.

Installation/QA • Review any sets and bends in the containment systems are appropriate for their use, i.e. slow swept bends for large SWA cables or data cables.

• It is preferable to use 2no 45 degree bends instead of a single 90 degree bend.

• Ensure changes in height are as gradual as possible to fully support cables.

• Gain early involvement in coordination meeting/drawing reviews on site for areas heavy in electrical i.e. specialist sound/lighting, kitchen installers, Utilities, Telecoms, Data.

• Arrange early for a lighting commissioning engineer to carry out toolbox talks on site prior to the lighting installation.

• Ensure regular QA snag walkrounds are held with each Subcontractor (minimum) once a week to ensure quality and consistency.

• Ensure document control is kept up and design changes communicated early.

• Review sign off of quality records weekly to ensure the files are always up to date.

• Communicate early between all relevant parties an appropriate method for wall closures and ceiling closures, this should be documented. (i.e. marked up drawings, coloured spray 4 stripe system etc).

• Prepare a snagging database to document all snags/defects as they happen rather than a full review. This should hopefully provide “zero snags” at the end of the project.

Avoiding Defects - Revision D – July 2013

Page 187

• Erico straps should be used in favour of “timber noggins” in partition walls.

• Regular coordination walkrounds to be agreed with the electrical contractor and other related subcontractors to ensure all secondary containment and power requirements are met and are as required.

47.0

Commissioning

Pre-Construction & Commissioning Management • Carry out a full and comprehensive induction with independent commissioning managers covering project deliverables, their scope, timescale etc to avoid uncertainty & scope gaps • Is there a clear understanding of the commissioning strategy?

• How are services to be commissioned – vertically, horizontally or a combination? Fabric tends to be constructed geographically horizontal, whereas services tend to require a large element of vertical installation & commissioning.

• Do requirements for sectional handovers necessitate partial commissioning? If so, are commissioning valves, loops or additional temporary systems required to facilitate construction/hand over?

• Are there any safety constraints on source to destination wiring terminations? Do these need to be 100% complete before commissioning can commence?

• Can a step-down policy to commissioning regarding MDB’s or SB’s enable earlier commissioning?

• Ensure that the commissioning manager is thoroughly vetted and their competency established. It is essential that if and independent commissioning management company is used they are a Commissioning Specialist Association (CSA) member.

• Ensure an initial commission ability review is carried out on the design drawings and fully documented. This should be reviewed and understood by the project team so that potential problems and areas of difficult access can be managed out early on.

• Ensure a pre-commissioning report is carried out and fully understood / utilised by the project team so that areas of difficult access & potential problems can be identified early on.

Page 188

Avoiding Defects - Revision D – July 2013

• A commissioning Strategy / Plan should be produced early on detailing methods of commissioning and tolerances. This should be agreed by client and consultant.

• A draft logic linked commissioning programme should be drafted and agreed with all parties.

• A list of required methods statements should be issued to the commissioning manager for comment.

• Off site testing must be co-ordinated and duly witnessed.

• Monthly principles meetings should be set up with all the subcontractors to discuss commissioning and handover requirements.

• Commissioning meetings should be conducted on a weekly basis and should be chaired and minuted by the commissioning manager. These meetings should have a weekly look-ahead and address perceived commissioning issues.

• Make sure that the commissioning manager keeps a daily diary and records labour on site plus all matters of relevant importance (Note – Kier supervisors should also keep a diary).

• All commissioning should follow CIBSE and BSRIA guidance as a minimum.

• A detailed list of handover requirements should be formulated and be included in the commissioning plan.

• Ensure the removal and cleaning of all strainers is included in the commissioning package (Pumps may burn out if strainers are blocked etc).

• Water flushing and sampling to be witnessed and recorded.

• All valve setting to be recorded and checked.

• Valves to be locked off once balance has been accepted.

• All ductwork damper settings to be marked and recorded.

• All building control and Fire Officer requirements to be understood – smoke test? Cause and Effect demonstrations?

• All BMS and Fire alarm interface points to be recorded and witnessed.

Pre-Commissioning and Management • The Hands on commissioning company should carry out a further commissionability review (based on construction issue drawings) as soon as possible to highlight any areas of Avoiding Defects - Revision D – July 2013

Page 189

concerns. This would be an enhancement to the independent commissioning managers design stage review.

• Hands-on commissioning should not start until installations are (suitably) complete otherwise systems become contaminated & must be re- commissioned.

• Water systems should not be balanced until the flushing and chemical cleaning process is complete otherwise systems can become contaminated & must be re-commissioned.

• On site inspections should take place as the systems are installed to check they are being installed as per the agreed drawings and strategy.

• Sample static testing should be tested and witnessed.

Water Systems Flushing • Ensure designs include method of providing water for flushing, especially if plant room is on roof.

• Check whether valves can be flushed through – if not install stool pieces.

• Ensure samples are taken on the incoming mains before starting the flushing & chemical cleaning process.

• A detailed method statement with marked up drawings should be issued and approved prior to any flushing work commencing.

• Water systems should not be flushed unless complete. Any remedial works risk contaminating the system; necessary remedial works (i.e. valves) should be carried out in accordance with the specialist flushing contractor.

• Ensure the removal and cleaning of all strainers is included in the commissioning package (pumps may burn out if strainers are blocked etc).

• Strainers should be checked for cleanliness.

• Water flushing and sampling is to be witnessed and recorded.

• The systems should be filled by the pipework subcontractor with biocide inhibited water ready for handover to the flushing company.

• All flushing companies will require a temporary water supply of 50mm. If the private main is connected early in the project and Page 190

Avoiding Defects - Revision D – July 2013

a fire hydrant ring is installed, utilise the hydrant supply for this purpose.

• Ensure all inline equipment can be flushed through i.e. valves, heat meters, sub meters etc.

• When flushing through heat exchangers, check with the manufacturer for possible restrictions on flushing operations.

• Check with the flushing company if thet are likely to have issues with certain types of heat exchanger material i.e. stainless steel • Consider whether the building can be flushed in one visit or if it is programme advantageous to flush it in more than one visit (to get heat on early in sections of the building) • Make sure there are sufficient flushing valves fitted on the pipework (min size 50mm Ø) • When DPCVs are fitted, ensure the installer does not connect the capillary pipework between the flow & return valves before flushing.

• It is advantageous to fit flushing bypasses at every underfloor heating manifold. Ensure the design includes for this • Consider buying temporary flushing pumps in the flushing subcontract order if the permanent system pumps are not ready or do not have the capacity • A discharge consent licence needs to be in place prior to flushing. Procure this as part of the commissioning subcontract order.

• Consider how the system will remain circulating after flushing (i.e. by the system pumps under BMS control). Failure to do this may result in having to re-flush the system as it cannot remain stagnant for more than 1 day.

Chlorination • All new private mains cold water installations greater than 63mmØ require chlorinating before the local Water Authority will make their connection. Thanes Water also requires the pipework to be flushed.

• If chlorinating the underground pipework early, make sure there is enough space at the boundary to connect the flushing rig at one end and a flushing / drain off point at the other (if required).

Avoiding Defects - Revision D – July 2013

Page 191

• Chlorinate less than 7 days before project handover, otherwise re-chlorination may be required. Alternatively, a robust “water outlet draw–off” schedule is to be implemented and managed.

Balancing and Commissioning • Agree design flow rates prior to any balancing commencing.

Ensure flow rates are as per the equipment selections.

• Prior to balancing ensure either all control valves are capped or power is available to actuators.

• All valve settings are to be recorded and checked.

• Valves to be locked off once a balance has been achieved.

• Test sheets should be complete and offered for inspection prior to any witnessing commencing.

• Once test sheets are agreed the systems can then be witnessed by the consultant so that system conformity can be confirmed.

• Balancing should be internally witnessed before being offered to the M&E Consultant.

Page 192

Avoiding Defects - Revision D – July 2013

Air Systems - Balancing and Commissioning • Agree design flow rates prior to any balancing. Ensure flow rates are as per the equipment selections.

• Ensure the system installation is complete including all ductwork prior to any balancing commencing.

• All grilles should be completed – not necessarily in full ceilings but can be installed individually.

• The external envelope should be installed and be complete prior to any final air balancing.

• Check requirements for doors to be installed to meet for pressure requirements.

• Any factors used for equipment should also be recorded and demonstrated.

• After satisfactory results have been achieved and witnessed then record all ductwork damper settings.

• Test sheets should be offered to consultant prior to on site witness to confirm acceptable.

• Check that the ducts are clean.

• Check that all filter media is installed and that the external design static is achieved by making sure the louvres are connected.

• Balancing should be internally witnessed before being offered to the M&E Consultant.

• When balancing is complete the system should be witnessed and confirmed as compliant by the consultant.

Electrical Testing General Requirements Electrical testing inherently involves some degree of Hazard. It is the inspector’s duty to ensure their own safety, and that of others, in the performance of test procedures. The safety procedures detailed in Health and Safety Executive Guidance Note GS38 Electrical test equipment for use by electricians should be observed.

• When using test instruments, safety is best achieved by precautions such as: o Understanding the equipment to be used and its rating.

Avoiding Defects - Revision D – July 2013

Page 193

o Checking that all the safety procedures are followed (Follow Kier Low Voltage Electrical Safety Procedures.) o Checking that the instruments being used conform to the to the appropriate British Standards safety specifications.

These are BS EN 61010 Safety requirements for electrical equipment for measurement, control, and laboratory use and BS 5458: 1978 (1993) Specification for safety requirements and their accessories. BS 5458 has been withdrawn, but is the standard to which older instruments should have been manufactured. o Checking that test leads including any prods or clips used are in good order, are clean and have no cracked or broken insulation. Where appropriate, the requirements of the Health and Safety Executive Guidance Note GS38 should be observed for test leads. This recommends the use of fused test leads aimed primarily at reducing the risks associated with arcing under fault conditions. • Particular attention should be paid to the safety aspects associated with any tests performed with instruments capable of generating a rest voltage greater than 50V, or which use the supply voltage for the purpose of the test in the earth loop testing and RCD testing. • Electrical shock hazards can arise from, for example, capacitive loads such as cables charged in the process of an insulation test, or voltages on earthed metalwork whilst conducting a loop test or RCD test. The test limits are intended to minimise the chances of receiving an electric shock during tests.

Required Competence The inspector carrying out the inspection and testing of any electrical installation must, as appropriate to his or her function, have a sound knowledge and experience relevant to the nature of the installation being inspected and tested, and to the technical standards. The inspector must be fully versed in the inspection and testing procedures and employ suitable testing equipment during the inspection and testing process. (Ideally qualified to City and Guilds level 2391.)

It is the responsibility of the inspector: o To ensure no danger occurs to any person, livestock or damage to property. o To compare the inspection and testing results with the design criteria.

Page 194

Avoiding Defects - Revision D – July 2013

o To take a view on the condition of the installation and advise on remedial works. o In the event of a dangerous situation, to make an immediate recommendation to the client to isolate the defective part. • The test certificates should be signed off by the installer, designer and the tester before issue to the client.

Reference documents: BS 7671: 2008 Requirements for Electrical Installations lEE Wiring Regulations 17th Edition HSGS 38 - Electrical test equipment for use by electricians BS EN 61010 Safety requirements for electrical equipment for measurement, control, and laboratory use BS 5458: 1978 (1993) Specification for safety requirements and their accessories

Avoiding Defects - Revision D – July 2013

Page 195

Fire Alarm / Life Safety / Cause and Effect • A Cause and Effect Matrix should be agreed with all parties as early as possible. Each interface should been identified and parties resolve any software issues prior to commissioning.

• All building control and Fire Officer requirements are to be understood – smoke test? Cause and Effect demonstrations?

•

Ensure early interface between fire alarm, BMS and lift installers and Mechanical plant such as air handling units, Windcatchers and Automatic doors.

• Be aware of requirements for building items required to install life safety devices – ceilings and walls. All items for fire alarm will be required to be installed prior to loop testing.

• Each item on the cause and effect matrix should be witnessed individually and with interface issues.

• All BMS and Fire alarm interface points to be witnessed and recorded.

• Confirm Building control and fire officer demonstration requirements – some may require black building test, smoke testing.

• Ensure all parties are invited to demonstration.

• A Final Commissioning report should be issued.

• Review whether the building has been commissioned correctly with the BMS working to the design parameters?

Reference documents: CIBSE Code M Commissioning Management BRE IP 8 04 Part 2 Whole Building Commissioning

Page 196

Avoiding Defects - Revision D – July 2013

48.0

O & M Manuals

• Check the specification or establish client requirement and ensure these are complied with.

• Hold element of payment of subcontractors until receipt and compliance confirmation of O & M information.

• When considering the use of an external compiler ensure that they are fed accurate data from site team, designers, suppliers and sub-contractors.

• Confirm from contract and client number and format to be provided. It is often worth challenging the contract as the client often does not need so many copies.

• If electronic manuals are required, establish format in advance, i.e. PDF’s are not fully editable.

• Clearly index all sections – agree index and format with client & CDMC. • Check language requirements – ensure English language versions provided.

• Collation of information for incorporation into O&M manuals should start on completion of the first works package.

• Develop matrix or method / responsibilities for tracking and monitoring information received.

• Ensure all included information is relevant to project.

• Ensure drawings are representative of as-built installation and annotated as such – construction team must check.

• Ensure all commissioning data is accurate and included to demonstrate the as installed environment.

• Smoke and fire dampers must be identified accurately on the drawings.

• Check electrical certificates have been signed by all parties as required.

• Ensure manufacturers literature when included is marked up with project specific information highlighted.

• Retain one full copy of O&M manuals for Kier Client Care department.

• Ensure one full set of documents are archived onto KIERdoc and that this mirrors what is handed to client.

Avoiding Defects - Revision D – July 2013

Page 197

• Document such as “Operation and Maintenance Manuals for Buildings, a Guide to Procurement and Preparation” CIRIA 507 will give further information in the absence of any Client directed guidance (extract below).

• If possible ask Client Care Manager to review documents prior to issue to client.

The Benefits of an O&M Manual A properly prepared O&M manual will produce significant benefits when it is used: o As the basis for timely, correct and efficient building maintenance, operation and planning. o As an information basis, including handover information, and as a source of reference. o As a basis for ensuring the most economic use of energy. o As a basis for ensuring awareness of health and safety aspects of the building construction, operation, maintenance and decommissioning. o As a basis for staff training. o To assist tendering.

with

facilities

management

competitive

o As a listing of emergency procedures. o As a reference for use during extension or refurbishment work or changes in use.

Additional derived benefits include: o Better designed and constructed buildings resulting from the project team’s improved understanding of: - Operational requirements - Maintenance requirements to meet the design life specified for the building o Easier ordering of spares and replacements. o The ready availability of information for components, e.g. limitations of use, materials and life expectancy. o A proper understanding by the occupants of the purpose and use of the building. o Retention of the inherent value of a building as a result of better maintenance.

Page 198

Avoiding Defects - Revision D – July 2013

o A reduction in disruptive and potentially costly effects of breakdown or failure.

• Consider if the O&Ms complete and do they stand up to scrutiny? In particular check … o Commissioning data not included or data error. o Ensure all as built drawings are accurate. o Ensure all information provided is relevant and English versions provided. o Ensure Electrical parties.

Certificates

signed

by

all

relevant

Reference documents: BSRIA handover,0 & Ms & Feedback BSRIA BG 4/2009 Soft Landings Framework

Avoiding Defects - Revision D – July 2013

Page 199

49.0

Working in Special Environments

Rail Working on or near a railway (including light rail and London Underground assets) is a specialist environment and those intending to do so MUST seek specialist advice and support from Kier Infrastructure UK (Rail) at the earliest opportunity for all such works no matter how small.

The Network Rail definition of ‘on or near the railway’ is if you are: • Within 3 metres (10 feet) of a line and there is no permanent fence or structure between you and the line.

• On the line itself.

• Carrying out engineering or technical work on a station platform within 1.25 metres (4 feet) of the platform edge.

Definitions for London Underground (LU) and Light Rail providers may differ from this so check.

If working in London, be aware that LU also have a safety exclusion zone around their tunnels. It is possible that surface based activities such as piling may infringe this, so if an LU tunnel is shown on the plans seek specialist advice.

In addition there are requirements when working in close proximity to the line. Again if in any doubt contact KIOS for advice.

• PPE and clothing requirements differ on the railway from Kier standards. This difference is compulsory.

• Specialist supervisory / safety staffing required when “on or near the railway”.

requirements

are

• Immediately report anything that could affect the safe passage of trains.

• Do not attempt to rescue anything that goes on the railway and raise the alarm immediately.

• Avoid the possibility of over-sailing the railway at any height or the theoretical collapse of a structure affecting the railway. If this is impossible seek specialist advice from KIOS. • Consider the use of scaffolding fans and/or fencing/hoarding to isolate the site from the rail environment.

• When working on a site near the railway consider the possibility of glare from equipment affecting the railway.

Page 200

Avoiding Defects - Revision D – July 2013

• When working on a site near the railway also carefully consider the use of coloured lights, clothing or signs especially in Red and Green.

Contact Kier Infrastructure UK (Rail) for advice if you are planning or carrying out work either on or near a railway or in close proximity to the railway.

Contact Antony Henocq (Rail HSQE) 07791718419 Reference documents: Rule Book Handbook 1 (GE/RT8000/HB1) Nuclear Working on a nuclear licensed site is a specialist environment and it is advised that Kier Infrastructure UK is contacted for advice.

Particularly : • The client will require us to work to the conditions of his nuclear site license. Therefore it is essential that you are aware of these conditions.

• It is the client’s responsibility to communicate to you the requirements of this license.

• Security is very much higher on a Nuclear licensed site and therefore considerable time will need to be allowed for procuring security clearances for staff and operatives.

• It is currently not possible for Kier to self deliver staff security clearances.

• Give consideration to subcontractor and delivery driver security clearances particularly cement truck drivers as this has high potential to delay or stop works.

• Give consideration to the possibility that key personnel may not be granted clearance and therefore will not be able to be allocated to that project.

• Security clearances take time to process and are not transferable, hence personnel required should be identified and finalised early.

Avoiding Defects - Revision D – July 2013

Page 201

• Currently there is no facility within Kier to progress security clearances so these must be obtained through the client.

• Tower Crane operators may need extra security clearance as their working location may overview a sensitive area.

• All documentation must be marked with a security designation.

As a general rule uncleared personnel may only see documentation marked “unclassified” or “Protect”. Recipients of documentation marked “Restricted” or higher who are not aware of the requirements for the protection of such documents should seek a briefing on the correct handling and disposal of such documents.

• The general requirements for documentation are very much higher for nuclear sites and will constitute a major cost to the project.

• Ensure that you understand the client’s requirements for traceability so these can be included in the relevant orders as these can be over and above the normal traceability supplied.

• Be aware that the higher than normal Quality Assurance regime required will require significantly more staff assigned to quality assurance • Be aware that security requirements will affect the time to construct the works through the need to gain various clearances and approvals for deliveries.

• If possible consider with the client the setup of a “nuclear island” where some or all of the rules may be relaxed.

• Generally explosives are banned from site – this includes nail guns, staplers etc.

• Cameras (including those on mobile phones) and video recorders are not generally allowed and will need to be discussed with the client.

• Ensure that you are familiar with the site safety arrangements including evacuation procedures – these may differ significantly from normal practice.

• Be aware that breaching certain site rules / requirements may constitute a criminal (not a civil) offence.

Page 202

Avoiding Defects - Revision D – July 2013

Marine Environments Marine environments can be challenging to work in and design for.

Certain aspects of marine requirements e.g. salinity, can extend up to 30 km inland.

• Ensure particular safety considerations are fully allowed for.

Are rescue boats required?

• Consider effects of tide – Tidal heights and tidal flows / rates – check tidal charts for approximate values.

• Take especial care not to pollute the environment.

• Be aware all rivers have a regular “Bore” in tidally affected areas. A Bore is temporary “wave(s)”,which on larger rivers can be significant and may “break” and therefore need consideration. Maximum bore heights occur in March and September.

• Be aware that river heights can change radically and without warning.

• Consider stakeholders. These may be more diverse than usual.

• Consider the “scour” effect on static structures in flowing water and protect against this.

• Consider rescue and safety requirements - this may include a rescue boat / equipment.

• Consider access requirements to the works and the river.

• Liaise with the local river authorities regarding navigation requirements.

• Consider the use of stainless steel or aluminium rather than steel.

• Consider protecting equipment from inadvertent submersion.

• Specialist waterborne equipment e.g. jackup barges, pontoons etc can be “long lead” procurement items.

Cofferdams • Ensure your Cofferdam is watertight.

• Is the cofferdam able to withstand a sudden rise in water levels above “flood” conditions.

• Is the cofferdam able to withstand credible impact loads (Rivers in spate can move some surprisingly heavy objects at speed).

Avoiding Defects - Revision D – July 2013

Page 203

• Plan works within the cofferdam for dry weather.

• Always ensure plant and machinery is out of the working area and on high ground before leaving site each day.

• Place fuel storage on high ground at least 10m away from watercourses.

Page 204

Avoiding Defects - Revision D – July 2013

Tunnelling • Consider safety / ventilation requirements at an early stage.

equipment

and

monitoring

• Consider specialist training requirements.

• Consider emergency emergency.

procedures

in

case

of

accident

/

• Follow Joint Code of Construction Practice (JCOP).

• Liaise with insurers in order to get their requirements for the tunnelling operation which must be adhered to.

• Consider quality requirements early particularly in respect of competency and control.

• Ensure ground movement monitoring regime is in place early (approx. 1 year) in order to take background readings.

• During engagement of a monitoring contractor make clear who is responsible for procuring permits, installation, maintenance and surveillance/reporting activities.

• Insist that the monitoring contractor can demonstrate that the data is “in control” with regards to quality variation.

• Ensure that an emergency reporting structure is defined.

Sprayed Concrete Lining (SCL) Sprayed Concrete Lining (SCL) is a specialist technique involving excavating and then immediately stabilising the excavation with sprayed concrete. It has advantages over pre-cast tunnel lining techniques but its apparent flexibility needs expert design, planning and control during construction by experienced staff.

• Nozzlemen are critical to the safe and high quality operation of the construction and must be properly trained.

• Concrete rebound level is critical to the quality of the finished product and must be controlled Tunnel Boring Machines (TBM) • TBMs are expensive to buy and run. They are also long lead procurement items and need to be considered early.

• Consider speed of production – the limiting factor for production should be how fast the TBM can bore and the removal of the excavated material. Other considerations such as pre-cast segment production are secondary.

Avoiding Defects - Revision D – July 2013

Page 205

• Consider how excavated material is to be treated (if necessary) and transported away from the site.

• Pay particular attention to other proprietary equipment e.g. conveyors, tippers etc. Ensure that the manufacturer’s limitations are not exceeded.

• If a light rail system is added to help transport in the tunnel then this must be run competently as a rail system and may also require signaling e.t.c – See section on Rail.

Reference documents: BTS “The joint code of practice for risk management on tunnel works in the UK” 2003

Bridges and Bearings It is planned to add notes on Bridges and Bearings to a future edition – If you feel that you can add to this section please contact those mentioned at the back of the book.

Page 206

Avoiding Defects - Revision D – July 2013

Contacts for additions/improvements: Simon Coultas

– simon.coultas@kier.co.uk

Nick Mann

- nick.mann@kier.co.uk

Neil Mellor

– neil.mellor@kier.co.uk

Ben Stevenson

– ben.stevenson@kier.co.uk

Tony Walters

– tony.walters@kier.co.uk

Nigel Weeks

– nigel.weeks@kier.co.uk

Paul Wilson

– paul.wilson@kier.co.uk

Avoiding Defects - Revision D – July 2013

Page 207