Construction Analysis - Construction Stages

ASSIGNMENT 2

FLIPBOOK SECTION 2D: Construction Stages, Details and Annotations ABPL20033 - Construction Analysis, Semester 2 - 2019 Dr Alberto Pugnale, Subject Coordinator Dr Sofia Colabella, Senior Tutor Petar Petrov, Tutor Hsieh, 996484, 15/09/2019 the Northcote House, Tutorial no. 28

Melbourne School of Design, photo by Sofia Colabella

STAGE 1

SITE PREPARATION: DEMOLITION Danger/warning signs at the site entrance for safety precaution. Temporary fences prevented any public access.

Basic amenities such as a portable restroom were brought to site for the workers and trades.

Ladder to access higher spots

Soil around the stumps was loosened so the footings could be easily pulled out.

Building proposal conformed to the ResCode to avoid going through planning for a permit, which saved time and money.

Demolition requires registered demolition contractor to ensure the safe removal of structures.

Services including electricity, plumbing, and gas were supended safely by the electrician and plumber etc.

Truck to transport the waste for recycling and disposal. Waste materials such as asbestos fibres must be discarded appropriately to prevent environmental pollution and public health risks. Recycled materials in good condition are exchangeable for money.

Land surveyor established the ground levels and site boundaries.

Wooden pegs were situated to indicate the building boundaries and walls’ positions.

Geotechnical engineer analysed the ground condition to produce a soil profile in determining the suitable types of foundation system. Due to Northcote’s sandy soil, extensive re-stumping was required for stability https://www.planning.vic.gov.au/permits-and-applications/do-i-need-a-permit https://www.epa.vic.gov.au/your-environment/waste/construction-and-demolition-waste#What

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STAGE 2

FOUNDATION SYSTEMS: EXCAVATION & PIPES LAYOUT Builder dug trenches by hand (with a showel) and with a mini excavator. Level staff and laser levels were utilized to measure the depth of the excavated area and the distance between two points.

Mini excavator due to site constraints 50mm of packing sand was layered on top of the soil for a levelled bedding. 0.2mm thick polytene building film was laid over the soil, acting as a damp-proof and vapour-barrier membrane to block the moisture from the soil to migrate upwards. All holes on and between the polythene sheets were taped before the pouring of concrete.

Capped to prevent dirt from entering the pipe during construction

Wheelbarrow to distribute the sand evenly across the surface

Plumber installed the PVC sewer piping and gave falls to the pipework to ensure that wastewater is discharged in the intended direction. The architectural drawings specify where the pipes should stick out to connect to sinks, toilets, and showers etc. The pipework should have flexible connections to enable relative shifts of the slab and ground. Laggings were warped around the pipes to protect them from getting damaged by the concrete.

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STAGE 3

FLOOR SYSTEM: GROUND FLOOR STRUCTURE

Accetable

Unaccetable - shear failures

A slump test measures the consistency and the workability of fresh concrete. The allowed tolerance for a slump up to 80 mm is Âą15 mm and from 80 up to 100 mm Âą 20 mm (CCAA).

Compression test is conducted in a lab for 12 months. The assessment provides grading for the concrete based on compressive strength.

Poker expel trapped air in the poured concrete Shovel to pack down the freshly pumped concrete mixture Concrete pump connected to the truck parked on the street

Pump the concrete on top of the face that is already placed

Pump the concrete into the trenches first.

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Compaction improve the concrete performance. Vibration, as one way of compacting concrete, reduces internal friction between particles, improving the workability of the mix. An immersion vibrator expels any trapped air in the freshly pumped concrete.

STAGE 4

STRUCTURAL SYSTEM: PREPARATION & COMPLETION OF BUILDING FRAME

Lift up and position the assembled stud wall into place.

Timber members were trimmed to the required measurements on-site on a table saw. Stud walls were constructed to form the walls’ structural frames.

Evenly spaced vertical timber studs (90x45mm) were nailed perpendicular to a bottom plate and top plate.

Plywood bracing was used on smaller areas (e.g. the corner walls of the light wells). Plywood sheets were nailed onto the stud walls with 50mm distance between each nail. Sheet bracing offers 6 times the strength compared to cross bracing.

The structural frame of the rear entrance (with sliding doors) was built with hot dip galvanized steel members. The vertical angle steels were connected a horizontal universal beam with top plates.

Stud ties greater resistance against lateral shear concrete screw anchor

Toe-nailing (nailing at an angle) provides a stronger, more rigid joint.

Two top plates for load-bearing stud walls and single for non-load-bearing Temporary prop to hold up the stud wall before the structure becomes fully self-supporting.

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Noggins attached in between the studs to stiffen the wall and restrain the vertical members from moving. Smaller-dimensioned timber pieces for the noggins are preferred for a even frame to attach plasterboards.

STAGE 5

INTERMEDIATE FLOOR STRUCTURE Structural steel members were lifted in place. The holes on the steel beams were pre-drilled in the factory before they were brought on-site. The holes allow timber piece to be easily attached to the universal beam with screws.

Structafloor

Hot rolled univerisal beam

Ceiling joists (seasoned) were attached to the timber packer between the I beam. An area of the first level overhangs the ground level in which the joists are cantilevered.

Timber attached to the I beam with screws

Joist hangers to attach the bearer and joists. The metal pieces open outward slightly when it is first purchased, so that it is easier to fit around a joist.

Construction adhesive Structaflor boards (3600 x 900) were attached on top of the joists with liquid nails (construction adhesive) for protection against moisture.

The joining piece between the particle boards can be taken out for boards that are facing corners.

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STAGE 6

ROOF SYSTEM: ROOF STRUCTURE & COVER Lintels were placed above any windows or door openings. Some windows touch the ceiling, thus the lintel is also a header for the attachment of ceiling joists.

Sarking insulates the roof and acts as a barrier to proect against moisture

Grated battens were positioned underneath the galvanised roof sheeting to give the roofing a two-degree fall. Colourbond flashings were warped around any edges and areas on the rooftop that are prone to water damage or leaks.

Roof sheet need to oversail at least 50mm in the gutter

Flashing Gutter - a gradual fall to discharge the stormwater into the downpipe. The lowest point of the gutter connects to the sump and rainwater head.

Wooden gutter board

Lysaght Klip-lok – fastening system The roof sheets click into place with the clip. https://www.no1roofing.com.au/l ysaght/klip-lok-406/

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STAGE 7

WINDOW SYSTEM: GLASS & GLAZING

All windows were prefabricated to the specified dimensions. The windows were fitted into the timber stud wall openings. The builder placed aluminium strip flashings and water-proofing membrane to the underside of the windowsill for all windows.

Weather strips and draught stoppers were fitted to the windows to avoid air leakage and increase the energy rating.

Vertical operable louvres can adjust the angle of shading according to the direction of the sun.

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Double glazing educes internal condensation and improves acoustic performance.

STAGE 8

WALL SYSTEMS: EXTERNAL WALLS & CLADDINGS Recycled brick - sustainable and reduce the construction cost

Colourbond flashings were placed in the gap between the faรงade of the ground level (brick) and the first level (timber cladding).

Temporary scaffolding for safe access to 1st level and roof

Wipe hole allows water to escape the facade

Brick ties at every third or fourth course of brick hold the two brick walls together Silicone

Expansion joints to give room for the brick wall to expand and contract.

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Backing rod

STAGE 9

INTERNAL PARTITIONS

Services, including the electrical wires, were placed the stud wall before internal cladding. They should be hidden behind the plasterboard.

Reflective foil insulation was installed throughout to stop moisture, air infiltration, and radiant heat. This enhance the thermal comfort and the energy performance of the house.

Bulk insulation (pink) was installed in the walls and ceiling as internal partition.

10mm plasterboard lining was nailed onto the stud wall after all the insulations. The building envelope must be sealed before the plasterboards are in the house as any water leakage could damage the plaster.

Ceiliing of ground level and the 1st finihsing floors were cladded with timber lining.

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STAGE 10

SERVICES & FINISHING TRADES

3 - Carpeter assembled the fixed furniture such as cabinets and kitchen island etc.

- Bricks were painted white.

- All light switches to be centred at 1100mm above the FFL. Dimmable lighting in the living area and bedroom - All socket outlets to be centred at 200mm - Deck with benches was built with concrete footings, stumps, bearer, joists and decking boards (25mm gap between deck and terrace slab) - Fan and heating systems were installed - The house was cleaned and inspected before handover.

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STAGE 1

SITE PREPARATION: DEMOLITION

Registered building contractor signed all relevant contracts with the building permit under their name. The contracts usually comprise a defects liability period during which the builder is accountable for detects. During construction, the builder is also required to carry insurances for both the on-site safety and the on-going construction work itself. All construction procedures should be controlled to be meet the S.A.A. Occupational Health and Safety Codes.

The demolition process began from the top (roofing) to the bottom (foundation system). Workers removed the roof sheets, rafters, and ceiling joists individually.

Existing vegetations that do not significantly interfere with the site access were kept.

The only viable access to the back of the site is on the west side.

Due to the site’s limited accessibility, large vehicles or equipment could not enter the site. Consequently, the demolition was mostly executed by human labour. The process was more labour-intensive, time-consuming, and expensive.

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STAGE 2

FOUNDATION SYSTEMS: EXCAVATION & PIPES LAYOUT Plastic bar-chairs hold mesh reinforcement in position above horizontal surfaces, allowing appropriate coverage of concrete over the reinforcements. The chairs are spaced at around 1.0m intervals in both directions.

(Ref. CCAA) Packing sand

Soil

150mm rebate

Trench Mesh Formwork made from timber boards were placed around the perimeter before the pouring of concrete. Formwork needs to be coated with release agent to aid the removal of formwork and to enhance the concrete finishes.

A 150mm rebate on the slab edge enables enough space for the brick cladding. Two courses of bricks sit on the damp-proof course (DPC) below the floor level.

Overlapping sheets of mesh reinforcement

2 x 4m sheets https://www. arcreo.com. au/product/s quare-reinfor cing-mesh

Polytene membrane

Trench mesh at T & L intersections should be overlapped by the full width of the mesh. (ref. CCAA)

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Trench meshes were installed to counter against the tensile force experienced at the bottom of the concrete footings. There should be a clearance of at least 50mm of concrete around the trench mesh in all directions such that no steel is exposed. The decision on the sizes/depths of the ribs and edge beams depend on the soil’s condition and the required level of strength. The building surveyor set the minimum bearing capacity of footing material for the Northcote House at 100KPa.

STAGE 3

FLOOR SYSTEM: GROUND FLOOR STRUCTURE Screeding A screed board was used to level the concrete after it was roughly distributed with a shovel. The plastic concrete is still malleable at this stage.

Screeding to level the surface

Bull-floating - initial smoothing of the surface right after screeding.

Trowelling Trowelling helped to create a smooth, dense surface, which was performed after the stab had time for some stiffening.

Curing Rapid moisture loss before the concrete has gained any strength can result in pre-hardening cracks (plastic shrinkage).

Spraying water on top of the exposed surface helps to achieve appropriate moisture retention during the hardening state.

Hydration Silicates and aluminates within the cement chemically reacts with water to make the concrete mixture harden. Cement begins to solidify after just an hour and the hardening begins after 24hours. Usually after 3 days, the surface becomes strong enough for workers to work on top of the slab.

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STAGE 4

STRUCTURAL SYSTEM: PREPARATION & COMPLETION OF BUILDING FRAME Galvanized hoop iron straps (with punched nail holes) were fixed to the stud walls to form a strap-brace. The bracings serve as diagonal tensile members, providing horizontal stability to withstand seismic activities.

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The straps are loosely attached to the stud wall as the workers assemble the stud wall on the ground.

The brace should form a 30o to 60o angle with the plate.

The iron strap wraps over the top plate within 150mm of a stud.

Nail the strap onto the stud wall

Strap brace is tensioned by a tensioner

Square hollow sections (SHS)

Staggered noggins over a central line so it is easier for nailing.

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Pairs of studs may be used at the corners

STAGE 5

INTERMEDIATE FLOOR STRUCTURE The boards are placed in a staggered manner to avoid any potential weak points around the corners of the boards. https://www.gunnersens.com.au/images/ stories/products/ParticleboardFlooring/str uctafloor_install_guide.pdf

Speed brace on the roof

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STAGE 6

ROOF SYSTEM: ROOF STRUCTURE & COVER

Anticon blanket provide acoustic and thermal insulation. It helps to reduce rain noise and control condensation. https://www.bradfordinsulation.com.au/-/media/br adford/files/anticon-blanket-datasheet.pdf

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STAGE 7

WINDOW SYSTEM: GLASS & GLAZING

Backing rod and silicone for expansion joint

30 x 70 mm timber batten Galvanised tek screw Galvanised steel section

Louvres move in clockwise direction and do not open past 90o angle

Shadow gap Plasterboard lining

Breathable sarking Vertical Timber Cladding

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STAGE 8

WALL SYSTEMS: EXTERNAL WALLS & CLADDINGS Timber battens were nailed in before the cladding, allowing a gap between the breathable sarking and the timber faรงade. The cladding was attached to the battens. The charred timber that was selected requires low maintenance and demonstrates a deliberate contrast in colour and material with the rustic brick base.

The double cavity brick wall was left with a 150mm wide cavity to accommodate the sliding doors and the sliding door track.

The design allows the door to disappear when it is opened.

Rigid Insulation in the cavity between the double brick wall Fire insulation Villaboard lining Hardie weather barrier reduces condensation build-up with breathable pores Bulk insulation Multiple common studs at corner joint to have a more stable joint ABPL20033 - 2019, Hsieh | 996484 |Tutorial No.28 | Petrov | p. 19

Sycon axon sheet as external cladding

STAGE 9

INTERNAL PARTITIONS Insulations (IN-07) were installed under the screed and to the edges of the slab and edge beams to achieve the energy rating requirement.

In screed hydronic floor heating was installed on top of the structural slab. Hot water heating coils were connected to a boiler then covered with 100mm of concrete screed.

The heating pipes were placed parallel to one another and equally distributed to provide even heat.

The screed is polished and used as the finished flooring.

External concrete paving slabs for the outdoor terrace was poured after the scaffolds were removed.

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STAGE 10

SERVICES & FINISHING TRADES

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