NFDC
Demolition Scaffolding
DRG 107:2014
INTRODUCTION The National Federation of Demolition Contractors (NFDC) is represented on the British Standards subcommittee which prepares the code of practice for demolition (BS6187) and is, along with the Institute of Demolition Engineers (IDE), the voice of the UK demolition industry. Founded in 1941 to help spearhead London’s post-Blitz clean-up campaign, the NFDC’s members are responsible for more than 90% of all demolition that takes place in the UK.
Today, the NFDC is committed to establishing safe working practices for its members and to represent their interests in areas such as training, safety, the environment, waste management, industry guidance, legislative changes and codes of practice. However, in researching and preparing the information contained within this/her document the NFDC cannot be held responsible for its subsequent use, nor for any errors or omissions it may contain.
Directors, managers and operatives who are required to work with, manage or supervise demolition or refurbishment projects where scaffolding is required, must carry out a risk assessment prior to the commencement of such work. The risk assessment should identify any hazards that may be associated with the work and the likelihood of harm occurring. In the event that risk assessment may identify a hazard, adequate and suitable control measures must be implemented prior to commencement of any such work. Those control measures will inevitably include, the correct use of the scaffolding, the inspection and maintenance of the components and at the very least require the protection of both employees and members of the public who may be required to pass close to or work in close proximity. Details of NFDC publications are available at www.demolition-nfdc.com or via:
National Federation of Demolition Contractors Paradise, Hemel Hempstead, Herts. HP2 4TF Tel: 01442 217144 Fax: 01442 218268
SPONSORS & FUNDERS:
The National Federation of Demolition Contractors would like to thank the following organisations for their help in producing this document:
NFDC WORKING GROUP: Howard Button Dr Terry Quarmby Chief Executive NFDC
Dorton Group
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SPECIFICATION FOR SCAFFOLDING This document may be useful in forming the basis for scaffolding requirements on general demolition and refurbishment sites and has been prepared to outline those arrangements as defined within this document. The intentions of this document are to clearly advise all persons affected by its contents, of the fundamental standard required in managing statutory/industry requirements in line with current safety standards and specific contract needs. It is further intended to reduce the instances of misinterpretation of required standards and to eliminate ambiguity regarding the acceptability of sub standard workmanship and or materials. It is not the policy or privilege of the NFDC, to dictate to any Contractor, his/her mode of operation or system of work. This document merely outlines what should constitute the minimum expected of a responsible and competent operator who is required to use scaffolding systems and or employ those who will erect and or manage such systems in order to carry out the primary function of demolition or refurbishment. The safety and robustness of scaffolding systems remains the responsibility of the Contractor who undertakes the design and construction. For the purpose of clarity the Scaffolding Contractor is referred to hereinafter as the Contractor. The end user of the scaffold shall be referred to as the Client or Main Contractor. Other bodies are referred to by their full titles.
The HSE (Health and Safety Executive) states that: 1.
2. 3.
4. 5.
Unless a scaffold is a basic configuration described in recognised guidance e.g. NASC Technical Guidance TG20 for tube and fitting scaffolds or manufacturers' guidance for system scaffolds, the scaffold should be designed by calculation, by a competent person, to ensure it will have adequate strength and stability. All scaffolding should be erected, dismantled and altered in accordance with either NASC guidance document SG4 for tube and fitting scaffolds or the manufacturers' erection guide for system scaffolds. For scaffolds that fall outside the scope of 'Basic Scaffolds' as described in bullet point 1, the design information should describe the sequence and methods to be adopted when erecting, dismantling and altering the scaffold, if this is not covered by published guidance as detailed in bullet point 2.
Any proposed modifications or alterations outside a generally recognised standard configuration should be designed by a competent person.
Handover certificates should refer to relevant drawings, permitted working platform loadings and any specific restrictions on use.
http://www.hse.gov.uk/construction/scaffoldinginfo.htm
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CONTENTS Introduction Specification for Scaffolding Section 1. Definitions Section 2. Requirements of the Contractor
2.1 The Scaffolding Contractor 2.2 Conduct on Site 2.3 Accounts
Section 3. Scaffold Components 3.1 BS EN 12811 3.2 Materials
Section 4. Specialist Scaffolds 4.1 System Scaffolds 4.2 Tower Scaffolds 4.3 Podium Scaffolds
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DEFINITIONS
Standards A name given to the vertical tubes. They are also known as uprights.
Ledgers Are the horizontal tubes which run parallel to the building and are fixed to the standards. A row of ledgers is called a lift.
Transoms The smaller tubes which are laid horizontally and are supported by the ledgers. They form the base on which the working platform is laid down. Couplers These are used to fix together standards, ledgers and transoms.
Platform Platforms are usually made from seasoned timber, although steel, aluminium and composite plastic can also be used. The material is laid and fixed on top of the transoms to provide the base on which workers will stand.
Guard rails These are tubes fitted across the front of each level of scaffolding to prevent workers from falling. A minimum of two guards rails are generally required unless a substantial alternative system is employed such as a heavy duty brick guard. Bracing Is a system used to give the structure rigidity;
Ledger bracing: Ledger bracing runs down the side of the scaffolding structure going diagonally from a ledger on one level to the next ledger on the next level, thus creating a zigzag shape. This creates stability and prevents the structure from falling sideways. Faรงade bracing: This bracing runs parallel to the building and gives the framework further rigidity.
Ties Metal ties, i.e. ring bolts or box ties, are used to secure the scaffolding to the building making the framework very secure. If no ties are used the scaffolding is classed as an independent structure, which in some circumstances can result in safety risks.
Sole Boards Not all scaffolding structures may need a base. Scaffolding erected on concrete or other hard and solid surfaces may be acceptable without one. Scaffolding erected on a less solid base needs to have a good solid foundation put in place. Sole boards are usually made from seasoned timber and are used to create a firm and secure base.
Sole Plates Are flat metal plates with a central spigot that slot into the bottom of the standard to increase the bearing size. Tube & Fitting A standard method of scaffolding using galvanised metal tubes and steel couplings.
System Scaffold A sometimes proprietary system of scaffolding using metal tubes fitted with an integral system of clips, wedges, rings and or hooks to enable fitting together.
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REQUIREMENTS OF THE CONTRACTOR 2.1 The Scaffolding Contractor
1. The Contractor should be aware that scaffolding requirements on many demolition sites vary from project to project. However, there are no variations where safety standards are concerned. It is the duty of all responsible Contractors to ensure the Health, Safety & Welfare of his/her employees and others who may be affected by his/her works. It is his/her duty to provide a safe place and plan of work. Further, it is the duty of their employees to work in a safe manner and to use all safety equipment etc provided for their use in the interests of their own safety and that of others who may be affected by their works. 2. The Contractor should ensure that he/she fully understands the Client’s requirements; that he/she meets all criteria as suggested within this specification and or any deviation or other arrangements included specifically for each individual project. Where there is any ambiguity regarding those requirements, the Contractor should liaise with the Client’s contract staff to resolve those issues prior to completion or hand over of the scaffold system. 3. The Contractor, on receipt of the Client’s tender requirements, would normally be expected to state on his/her (return) tender/contract agreement that he/she will comply with the Client’s requirements and shall ensure that sufficient materials are available to carry out the works. The Contractor must have the means and ability to meet the Client’s requirements and programme.
4. The Contractor must produce a written Safe System of Work (Method Statement) and specific risk assessments, which shall be submitted to the Client’s site team for approval prior to commencement on site. All such documentation including the compliance sheet should be available on site at all times and should be read and understood by the Contractors employees. Where a designed scaffold is required, a detailed drawing with calculations shall be submitted by the Contractor prior to commencement for approval by the Client’s safety manager/contracts manager and their appointed structural engineer. This document must be carried to site and shall be available for inspection at all times. The Contractor should not deviate from the agreed design at any time unless such changes have been redesigned with appropriate calculations and agreed by all relevant parties.
5. It is generally assumed that the Contractor will employ ‘Direct’ labour only. However, where the use of contracted labour gangs or sub-contracted scaffolding companies are employed, the contractor is expected to comply with all legal and statutory conditions and to adequately manage those parties under his/her control.
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2.2 Conduct on Site 1. The Contractor should ensure that their representative reports directly to the Client’s site manager/supervisor on arrival at site. All Contractors staff must be fully inducted and instructed in the site rules and safety system in use. The Contractor must comply with the instructions of the Client’s site manager/supervisor at all times. The Contractor must comply with all Statutory Acts and Regulations relating to his/her works, or where their works are likely to affect the Health, Safety & Welfare of others. He/she should comply with all Guidance, Codes of Practice, British Standards and European Directives relating to their works. The Client or Main Contractor would normally reserve the right to instruct the Contractor to remove from site, any individual who fails to meet these requirements.
2. The Contractor should undertake his/her works as stated within the written plan of work and where applicable, in accordance with his/her detailed design drawing & calculations. The Client or Main Contractor shall not undertake to alter the scaffold in any way and shall generally demand that it be the responsibility of the Contractors site management to inspect the scaffold, to note any discrepancies or mistakes and to correct such deviations prior to expected hand over. Any noted deviations by the Client’s site team or visiting management etc, from this criteria, should be corrected immediately on discovery at no cost to the Client. Where these deviations are not corrected or are ignored, the scaffold system will not be fit for use and therefore the agreed hire period of such scaffold systems would be suspended, until corrections are completed and acknowledged, at no cost to the Client. Following acceptance of the hand over certificate it will be the responsibility of the Client’s site team to continue to inspect the scaffold, until further alterations or reductions to the scaffold are commenced. The responsibility for further inspections thereafter shall fall to the Contractor until a subsequent hand over is accepted.
3. The Contractor shall nominate a person in charge of work, who shall ensure that all safety measures as stated within the Contractor’s written plan of work and or as outlined within the Client’s Health & Safety Plan, shall be strictly adhered to by all of the Contractor employees and any others who may be employed to assist in the Contractor’s works. The Contractor must ensure that all Personal Protective Equipment (PPE) issued to his/her employees is worn correctly and used for the purpose of its design. Safety harnesses are to be worn by all scaffolding personnel, who must ensure its correct usage in line with SG4, SG16, SG17 & SG19. The Contractors operatives must be clearly identified from all others and shall wear high visibility clothing with the company logo displayed. The Client or Main Contractor would normally reserve the right to insist on the removal of all persons, from site, which persistently breach the Health & Safety Regulations and or the Safe System of Work conditions.
4. Where Welfare facilities are to be supplied by the Contractor, they shall meet all safety & hygiene standards, be adequate for the number of operatives on site and must be cleaned, replenished and maintained to statutory requirements. Facilities supplied by the Client for the Contractors use shall be used and maintained to the Client’s standards. Failure to comply with this requirement will result in the withdrawal of use of such facilities and the Contractor shall be expected to bring to site his/her own facilities or seek alternative arrangements.
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5. The Contractor should be a full member of the National Access and Scaffolding Confederation (NASC) and shall be bound by the Associations code of practice and membership criteria. All scaffolding operatives should be holders of a current scaffolding registration card. Operatives should be registered under the Scaffolding Registration Scheme (CISRS) or be under training for such. The Contractor must demonstrate his/her competency levels, training levels and safety knowledge. When required to work on sites managed by a member of ‘The UK Contractors Group,’ he/she must be able to meet the standards set by that Group, especially where operations by the Client are in direct relation to work undertaken on such sites. Further, the Contractor will be expected to attend any safety or contract meeting as is deemed necessary and relevant, for the effectiveness of the site operations, provided always that he/she will be given sufficient prior notice of such meetings. 6. The Contractor should be afforded all reasonable assistance by the Client’s site team to ensure that his/her works are carried out safely and efficiently. Dates for commencement of erection or delivery of materials to site must be pre-planned and agreed with the Client’s site/contract staff. The Client will endeavour to provide sufficient working areas for the use of the Contractor in the erection and dismantling of the scaffold system, provided that those works are scheduled and acknowledged as being reasonable given the status of the site. The Contractor in turn, must understand and be mindful of the Client’s works and shall give all reasonable assistance to the Client’s site team to ensure that he meets the planned program dates and that the safety integrity of the site is not compromised by the condition of the scaffold or its components at any time.
7. In undertaking works to supply, erect and dismantle scaffolding, equipment and materials of any nature, the Contractor would be expected to agree and conform to the requirements and conditions of this specification. Further, the Contractor shall ensure that all fixings, couplers, tubes and boards etc supplied to site for the use by his/her operatives meets or exceeds all safety standards and industry standards as directed and specified within the British Standard Institute and European Union Directives. In addition, the Contractor shall pay particular attention to the requirements as outlined within sections 4, 5 & 6 of this specification. In the event of any disagreement arising on site, regarding the integrity of the structure, materials or manner of execution of the scaffold works, an independent specialist scaffolding company/individual, to be agreed between the Client and the Contractor, shall be engaged. Their recommendations shall be final unless and until referred to adjudication or litigation. 8. The Contractor must ensure that the Client’s site team are advised of the names and contact telephone numbers for responsible persons within his/her organisation that are available on a 24 hour emergency basis. Similarly, the names and telephone numbers of those responsible persons on call out should be registered on site.
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9. Where a scaffold is required for access purposes to; or for the formation of an asbestos stripping enclosure, the Contractor must be a Licence holder in accordance with the statutory requirements laid down in The Control of Asbestos Regulations 2012.
Doctors Note:
Although it is not the law, a competent scaffolding company will be members of their trade association just as we insist on NFDC membership. Therefore you should be assured of a quality service from companies holding NASC membership whose operatives are trained to and in possession of CISRS cards.
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2.3 Accounts 1. Generally, the Contractor must show his/her fixed price lump sum return, and all costs relating to the enquiry. These costs should be itemised to show erection/dismantling, hire, supply of materials, day works and incidentals as may be required or requested. 2. The Contractor would normally be expected to quote the dedicated order number (if given one) assigned to each order when submitting his/her invoice. The invoice should detail all costs relating to those orders with corresponding dates for referencing by the Client’s accounts department. No payment of invoice will normally be sanctioned without a relevant order number.
3. Where variations to the original order have been recorded/noted, payment should not be expected unless accompanied by an order which supersedes or is in addition to previous orders.
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SCAFFOLD COMPONENTS 3.1 BS EN: 21811, Temporary works equipment, scaffolds, performance requirements and general design As stated earlier, the requirements for scaffolding are likely to vary from project to project. The scaffold may be used as follows; a) b) c) d) e) f)
as a means of access and egress between floor levels as an emergency route as a practical dust inhibitor as the sole safe means of access and egress as the working platform in which to reduce the structure to provide structural support and faรงade retention systems
Whatever its intended use, the scaffold must be robust, rigid, well secured and have sound foundations.
Every scaffold whether, free standing, independent tied, slung or suspended shall be sufficiently and properly strutted or braced, as necessary, to prevent collapse or sway. It must be rigidly connected to the building or structure, unless specifically designed to ensure stability without such connections. Where specified and when erected in public places, the scaffold must be well lit, alarmed, tubes flush with all couplings and fittings, end caps fitted, signed and secure. Members of the public and in particular children should not be able to gain access at any time. Scaffolds must only be erected by trained and experienced scaffolders who must work under the supervision of a competent scaffolding supervisor/leading hand. All scaffolds are to be erected to conform to BS EN 21811-1:2003, Temporary work equipment, scaffolds, Performance requirements and general design.
Doctors Note:
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It should be understood that a maximum of two lifts height, which is unconnected/untied to the building, shall be present/acceptable at any time. 1. 2.
3.
4.
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A maximum of two lifts only should be allowed to be free standing at any time. Scaffold ties should be installed at every lift to ensure integrity during demolition works in accordance with BSEN:21811. Scaffold ties must not be removed without the approval of the appointed Temporary works co-ordinator. Scaffolds must be designed in accordance with TG20:13 or by a competent scaffold designer. All scaffold must be erected and maintained in line with BS5975 for temporary works with a competent Temporary works co-ordinator and Temporary works supervisor ap pointed on site.
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3.2 Materials Base Plates & Sole Boards The foundation of the scaffold is paramount to the safety and security of the system. The foundation must always be adequate to carry the load of each standard and in particular the self weight of the scaffold structure and weight imposed by the working load. A steel base plate must always be placed beneath each standard. Standards are not to be allowed to stand directly onto any surface. Steel base plates should be at least 150 mm x 150 mm, a minimum of 5 mm thick and with a central shank of not less than 50 mm. If the Contractor wishes to use a base plate constructed from another material, he must inform the Client prior to its use and satisfy him/her as to its safety and integrity. Where the surface is soil, ash, hoggin, gravel, asphalt or any type of flooring or paving etc which may not alone bear the weight of the base plate, the weight should be distributed by use of a sole board or sole plate. The sole board is to be a minimum of 1000 cm² (with a minimum dimension of 219 mm), not less than 35 mm thick and should support at least two standards where ever possible. On sites where ground is soft or has been disturbed, the sole plate area should be not less than 1700 cm² (single sole plate) or 3400 cm² (two combined).
If the Contractor wishes to use a sole board/plate constructed from other than timber, he must inform the Client prior to its use and satisfy him/her as to its safety and integrity. On slopes exceeding 1 in 10 a thorough check is to be made of the surrounding ground to determine its ability to maintain the integrity of the scaffold. Where appropriate and necessary additional foundation supports are to be fitted.
There should be no ambiguity as to the condition or surface preparation needed to be in place prior to erection of the scaffold. The Contractor is to liaise with the Client at as early an opportunity as possible, to ensure that all ground conditions are favourable and adequate.
Doctors Note: 1.
It would be wise to regularly check the condition and integrity of all base plates particularly after heavy rainfall
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Tubes The integrity of the tubes in their ability to carry loads cannot be marginalised. The condition of the tubes will give a good indication of their strength. Tubes must be straight and free from splits and cracks. They shall not display excessive dents or corrosion and must be cut square and clean at each end. No tube shall be flame cut. Galvanised tubes are to be used on all sites. Black steel tubes may only be used where prior permission has been given. At no time shall aluminium tubes be acceptable to form any scaffold structure other than a ‘Tower Scaffold’. Tubes should be manufactured and tested in accordance with BS 1139 part 1 ‘Specification for Tubes for Use in Scaffolding’ and or where superseded by BS EN 39:2001
Storage of tubes on the scaffold structure will only be sanctioned by prior agreement with the Client’s site manager. All spare tubes and or those dismantled during the reduction process must be cleared from the scaffolding on a progressive basis. The storage of tubes around the foot of the scaffold will not be allowed without prior agreement with the Client’s site manager. The Contractor should adhere at all times to the conditions described within Section 2.1, 2.6 & 2.7 above.
The ‘bombing’ of any equipment to the ground will not be allowed at any time. The Contractor can be expected to be instructed to remove any operative guilty of such activities from the client’s site immediately on discovery of such acts. Couplers & General Fittings All couplers must be manufactured, tested and employed to the individual British Standards and in particular to BS EN 21811 & BS 1139 Part 2 and or where superseded by BS EN 74-1;2005
Couplers should be free from rust with workable threads that tighten. They must not be cracked, bent or twisted and should be used only for the purpose for which they were intended.
‘Ginny Wheels‘Wheels‘ employed to erect tubes and fittings should be stamped with the safe working load and have current test certificates available for inspection. Ropes must be of 18 mm diameter and shall be adequate and safe for the task.
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Boards & Boarded Lifts All scaffold boards are to conform to BS 2482:2009 ‘ Specification for Timber Scaffold Boards’.
Each board must display the British Standard Number, the manufacturers ID mark, the letter M or V denoting machine or visually graded and the word “support”, followed by the maximum span in metres, over which the board is to be supported. The maximum span between transoms for a standard 38 mm thickness board, shall be no more than 1.5 metres. The use of any board not able to meet the above criteria must be brought to the attention of the Client’s site management team for approval. Approval of use will only be sanctioned where the Contractor can provide adequate proof of safety and integrity. The maximum span of any such board is to be reduced to 1.2 metres which should be clearly displayed on each board.
No boards are to be laid down that are excessively warped, worn, cracked, split, knotted, cut or with damaged bands. Boards used for any purpose other than the manufactures intention will be required to be removed from site. All top lifts are to be fully close boarded. Scaffolds of 8 lifts and over, shall have the top two lifts fully close boarded. Timber plyboard or similar, when used, shall be cut to fully enclose around all tubes and be butted up to the building elevation to eliminate the dropping through of tools and debris from the dismantling process.
Toe boards on the external elevation are to be fitted and guard rails on both the internal elevation and the external shall be fitted at all times. Tripping hazards are to be eliminated by use of filleted joints etc where overlapping of boards is unavoidable.
Doctors Note:
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1. Poor quality boards can easily be affected by changes in the weather. Only continuous monitoring can inform you of condition and durability 2. Cutting plywood profiles to the shape of the building only has to be done once as they can be transferred to each deck level as the scaffold is reduced 3. Where practical and possible, all lifts should be placed to marry in with the buildings floor levels to avoid trip hazards or gaps 4. All boarded lifts should be free of debris and stored materials 5. In areas that may be exposed to high winds T clips are recommended to hold down the boarded lift.
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Ladders Unless otherwise agreed, all ladders used on the Client’s sites are to be either Pole ladders or Aluminium ladders. All such ladders are to meet BS EN 131:2007.
All ladders must be in good condition and strong enough for the purpose for which they are intended. Any ladder that displays warping, splintering, cracking, bruising, or worn or missing rungs shall be taken out of use and marked as defective. It is important that each ladder is secured at its top and where necessary at the bottom also. (stiles only, never rungs) Ladders must be erected on a sound base and shall angle against the scaffold at a ratio of 4 up to 1 out (75°). The ladders are to protrude above the landing platform by at least one metre but not to such an excessive height that may make their base unstable. A wide gap between the hand rail and the ladder should be avoided, with all such conditions made safe by the placing of a braced tube as extra support. Reinforced Plastic Sheeting Where the scaffold has been specially designed to take the wind loading from sheeting it is common for the Client’s to supply his/her own reinforced plastic sheeting unless there is a prior agreement between the parties for the contractor to supply such sheeting or debris netting. The Contractor is expected to erect the sheeting using his/her own ties (unless a prior agreement is in place).
Sheeting should be erected from top down and tied at every lift to every standard/ledger joint and between these points as appropriate. The sheeting is to be overlapped, (top of bottom sheet over bottom of top sheet) to provide a fully enclosed wind and debris break. Horizontal tubes to the external face of the scaffold should be flush with the standards to provide an even surface for ease of fixing. It should be noted that no egress of dust, tools or debris should be possible at all if lifts are correctly tied. The Client shall not be deemed to accept the hand over of any sheeted scaffold that fails to meet the required standard. The finish of the sheeting should be taut and in line with any logos uniform. Torn or worn sheeting damaged during the erection, is to be replaced on discovery. The contractor would not be expected to accept responsibility for costs incurred in making good.
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Debris Fans All fans erected for use on the Client’s sites are likely to be Class B or C structures and as such are the subject of specific design criteria. All fans must meet the needs of the site to provide the level of protection expected. They should be suitable in width and at an angle capable of capturing and retaining any debris expelled from the working level.
Class A – Light duty, maximum loading of 0.75 kN/m² for protection from falling paint and mortar. Class B – Medium duty, maximum loading of 1 kN/m², for protection from aggregate and bricks falling from no more than 10 m. Class C – Heavy duty, for protection from bricks falling further than 10 m or larger heavier items. Class D – For protection from persons or similar weights falling from less than 10 m.
Fans are to be fully, double close boarded and topped with plyboard or similar. (Sheeting placed between boards is acceptable at lower fan level). All such structures must be erected to their design standard at specified heights. They are not to be used to store spare scaffolding materials, at any time. Debris collected on the fans must be contained on close boarded lifts level with or immediately below the fan placement. These lifts must be accessible at all times, for personnel to undertake periodic and progressive clearance.
Doctors Note:
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1. Avoid applying any sheeting, i.e. to ward off rain, dust or wind, to an access or tower scaffold unless it has been designed for that purpose. The effect it can have as a ‘sail’ could have devastating consequences.
1. Metallic ladders are becoming common place on access scaffolds, but just as tower scaffold tubes have to be rejected with dents greater than 5mm deep, this applies to ladders too.
1. Debris fans can rarely guarantee to stop everything that may fall off the scaffold. Therefore, other engineering controls and safe working procedures must be enacted to work in conjunction.
2. Debris fans must not be used for the storage of materials.
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Ties & Bracing The continued integrity of any scaffold, to remain rigidly fixed to the building or structure, depends on the number of ties and their ability to provide a secure hold. The Contractor must be mindful of the type of work being undertaken by the Client, in that sections of the structure or building will be gradually reduced in various stages and possibly at various levels. It is therefore essential that the placing of ties is undertaken in such a manner that the continued integrity of the remainder of the scaffold is assured when certain numbers of ties have to be removed. The Contractor must liaise with the Client to clarify the sequencing of the demolition works, in order to place ties appropriately. Similarly, bracing of the scaffold structure should be considered to ensure that lifts are secure as the structure is reduced.
The Contractor is to take advantage of available structural columns. pillars and rebates to fix his/her ties. Ties must not be fixed to parts of the structure or building that are to be removed at an early stage of the dismantling works ie soft strip stage where timber architraves, windows, doors and non-load bearing walls etc are to be stripped out. Should the Contractor need clarification of this point, he/she must liaise with the Client’ prior to the fixing of any tie. Through Ties must only be fastened with Right Angle Couplers (Doubles) and should span two standards. Where ledgers are to be the anchor point, they must span both ledgers within 300 mm of the standards. Bracing may be secured with swivels.
Screw Ties must be permanently fixed, with an agreed percentage, pull-tested to confirm suitability. All ties are to be placed at specified recommended intervals depending on the square metreage of the structure (in accordance with BS EN 12811) and at alternate lifts every 6 metres along the entire length (subject to the type of scaffold and loading capacity of the ties) and in accordance with NASC guidance TG4:11.
Doctors Note:
1. When using through ties it is advisable to place them on every level.
2. When ties and bracing have to be removed to facilitate the reduction process they should only be taken off when a full inspection of the remainder by the scoffold designer and a TWC has determined that the scaffold will maintain its integrity and security.
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4.1 System Scaffolds The use of System Scaffolds on demolition sites shall be by prior approval only and where prior agreement has not been reached with the client shall, in general, be confined to a maximum of three lifts height only. Through experience of use in high rise structures, it has been revealed that such structures will not stand the rigors of demolition activities unless they are substantially strengthened. For general practical application, in the use of ties and bracing, multi-lift scaffolds using system scaffolding are for the most part unworkable as the platform levels cannot be adjusted to suit every contingency. The Contractor is to be aware that the relaxation of this rule is unlikely to be negotiable without detailed design and practical use assurances. Where temporary staircase access is required then system staircases will generally be the preferred option.
4.2 Tower Scaffolds A Tower scaffold can generally be described as being lightweight, with four ‘legs’ that are adjustable or on castors to make them mobile, free standing and with outrigger support. They may be manufactured from steel, aluminium alloy or fibreglass. There is no legal requirement for a scaffolding contractor to be employed to erect such a structure. However, they must only be erected or dismantled by people who are competent to do so if they are trained. Differing types of towers may be erected in different ways, therefore a manufactures instruction manual should always accompany the tower. Some information is often written on adhesive labels stuck on the individual components. Use only the recommended type of tower suitable for your work and work environment. For example, when working in close proximity to unsheathed ‘live’ overhead electrical services, a fibreglass framed tower is obviously preferable. All scaffold towers must be capable of meeting the requirements of BS EN 1004:2004
Stability A scaffold tower must be erected on firm and level ground. Bricks or blocks etc should never be used to take the weight of the tower.
The taller the tower the more likely it is to become unstable. Always check the safe height to base ratio in the instruction manual or manufactures notes to hirer. Towers used outside or in exposed conditions are more likely to be affected by the weather than those used inside. Towers used outside are to have a maximum working platform height of no more than 3 times the minimum base dimension. Towers used inside may be extended to have a working platform height of no more than 3.5 times the minimum base dimension. Using this guide; if the tower base is 2m x 3m the maximum height would be 6 m outside and 7m inside. Therefore if any tower is required to be extended beyond these guide limits, it must be fitted with outriggers to extend the minimum base ratio and or firmly secured to the building by suitable and adequate ties and or tied to another rigid scaffolding system.
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Ties Ties should be used when the tower goes beyond its safe height to base ratio, beyond the limits of the stabilisers or outriggers or if there is a danger of instability. They should be rigid two way ties fastened to both uprights of the frame with load bearing right angled or swivel couplers. Only couplers suitable for the 50.8mm diameter of the tube of the tower should be used. Ideally, ties should secure to the face of a solid structure or by means of anchorages. The tie frequency may vary depending on the application but, as a minimum, they should be at every 4 metres in height.
Access Always ensure that there is safe access and egress to and from the working platform. It is not safe to climb the outside of the tower except where; A built in ladder has been provided in the end frames that the manufacturer has designed for that purpose. However, a check with the manufacturer should be undertaken before fitting any ladder to the outside as well as making sure there is a secure hand hold at the landing place. In most cases a purpose made ladder can be attached safely on the inside of the frame. Edge protection Suitable edge protection should be provided where it is possible that a person can fall. Guard rails should be at least 950mm high and toe boards at least 150mm high. An intermediate guard rail or suitable alternative should be provided so that the unprotected gap does not exceed 470mm. Brick guards etc may be used instead of the intermediate rail so long as they are strong enough and placed to prevent someone falling through. A tower scaffold needs to be fitted with the same safety features as that of a fixed scaffolding. Moving the tower Before attempting to move the tower from any working position or after erection you must check that there are no power lines or other overhead obstructions in the immediate proximity or along the route to the workplace. Always ensure that the ground is firm and level and that any voids are either filled in or have been plated over. When moving the tower, push or pull only from the base, never use powered vehicles. Never move it while there are people or loose materials on the upper platforms and always secure tools and materials left on top or take them down altogether. Never attempt to move a tower in windy conditions. Once moved the scaffold tower brakes must be applied to all wheels.
If the towers are to be used in public places, extra precautions may need to be taken: • Minimise the storage of materials & equipment on the working platform. • Erecting barriers at ground level to prevent people from walking into the tower or work area. • Removing or boarding over access ladders to prevent unauthorised access if it is to remain in position overnight or when unattended; You may also need to check if you require a license from the local authority if erecting towers on the pavement or public highway. Inspection All tower scaffolds must be inspected by a competent person; 1. Before use 2. After substantial alteration and 3. After any event likely to have affected its stability
If the tower remains in the same place for more than 7 days, it should also be inspected at regular intervals (7 days max’) and a written report made. Any faults that are found must be put right before further use.
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Maintenance All components and their parts should be regularly inspected to identify damage, particularly to welds. Lost or broken parts should be replaced and any tubing with indentations greater than 5mm should be put to one side for manufacturer repair or replacement. Adjustable leg threads and castors should be cleaned and lightly lubricated to keep them free running. Cement or concrete residues are to be cleaned off all components before being allowed to set as the cement reacts with aluminium to weaken the material. Platform boards are to be replaced if cracked or cup locks bent, broken or missing.
Windy conditions Erecting, moving and or working on a scaffold tower during windy conditions can be hazardous as well a danger to others. Getting real time information on wind conditions and or forecasts on expected weather conditions is an important aspect to consider. Localised weather forecasting is common and can be accessed via radio, television, smart phone and other media avenues. Many organisation use the Beaufort scale to determine wind conditions and velocity. Those using tower scaffolding outside of a structure should beware of high winds in exposed, gusty or medium breeze conditions. It is recommended that in wind speeds over 7.7 m/s (17 mph) all work on the tower should cease. If the wind becomes a strong breeze, it is expected to reach 11.3 m/s (25 mph) and the tower should be tied into a rigid structure. If the wind is likely to reach gale force, over 18 m/s (40mph) the tower should be dismantled.
Beaufort Scale examples
TG20:13 contains a simplified wind map system with an automatic wind calculator that will calculate your current location, height above sea level and wind speed on site.
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4.3 Podium Scaffolds
A relatively new comer to the construction/demolition industry and used extensively for asbestos removal is the podium step or ‘hop up’ as they are commonly called. This is a lightweight access scaffold that can be fitted with castors or straight legs or both. Podiums are manufactured at a variety of heights and most have the capacity to fold away, have integral hand rails and platforms and are extremely mobile. However, as with all access towers they should be erected and used correctly by competent people. Podiums may also be fitted with outriggers for extra rigidity although most are designed to be free standing. Podiums are a safe and simple means of access to relatively low level areas. Following the safety rules for erection and use should ensure a risk free working methodology.
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DO’S AND DON’TS Do consult your manual or supplier if in any doubt as to the safe working protocol Do face the folding back section when ascending or descending Do ensure the gate is closed and locked before use Do ascend and descend using the access provided Do inspect the unit before starting work Do lock any castors prior to use Do beware of finger traps
Do not use on loose or slippery surfaces Do not use on an incline or uneven surface Do not overreach when working on the platform Do not move the unit with anyone standing on it Do not stand on the access step or ladder to work Do not place anything on the platform to gain extra height Do not exceed the safe working load (usually you and your hand tools)
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FURTHER READING BS EN 12811-1-2:2003 BS EN 12810-1:2003 BS 1139-6:2005 BS 2482:2009 BS EN 74-1:2005 BS EN 39:2001 BS EN 131-1:2007+A1:2011 BS EN 1004:2004 TG20:13 replaces TG20:08 Work at Height Regulations 2005 SG4:10 preventing falls in scaffolding SG17:08 fall arrest equipment HSE Construction Information Sheet No 10 (rev4) HSE Construction Information Sheet No 47 HSE Construction Information Sheet No 49 Health & Safety in Construction HSG150 Work at Height Regulations 2005 part 1 Provision & Use of Work Equipment Regulations 1998 Management of Health & Safety at Work Regulations 1999
Here is a list of other relevant, useful guidance and codes of practice that may be consulted in conjunction with this guidance note:
1. Provision and Use of Work Equipment Regulations 1998 – ACOP L22
2. Construction (Design and Management) Regulations 2007 - ACOP L144
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Produced by the National Federation of Demolition Contractors.
Requests to copy or reproduce any part of this publication should be made to:
National Federation of Demolition Contractors Paradise Hemel Hempstead Hertfordshire HP2 4TF Tel: 01442 217144 Fax: 01442 218268 www.demolition-nfdc.com
NATIONAL FEDERATION OF DEMOLITION CONTRACTORS Resurgam House • Paradise • Hemel Hempstead • Hertfordshire • HP2 4TF Tel: 01442 217144 • Fax: 01442 218268 • www.demolition-nfdc.com
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NATIONAL FEDERATION OF DEMOLITION CONTRACTORS Resurgam House • Paradise • Hemel Hempstead • Hertfordshire • HP2 4TF Tel: 01442 217144 • Fax: 01442 218268 • www.demolition-nfdc.com