Construction of Residential Buildings (ABPL20042) - House Watch Assignment

CONSTRUCTION OF RESIDENTIAL BUILDINGS HOUSE WATCH ASSIGNMENT MELISSA CHONG / 864703

Content

CONTENTS 1

Introduction: Site Descriptions 1.1 Houses in Point Cook 1.2 Arve townhouses in Ivanhoe

2

Pre-construction phase 2.1 Key players involved 2.2 Building Act 2.3 Building Regulations 2.4 Drawings 2.5 Land survey and site plans 2.6 Soil tests 2.7 Permits 2.7.1 Planning Permit 2.7.2 Building Permit 2.8 Termite control 2.9 Overall process (simplified)

3

Construction Phase 3.1 Site preparation 3.1.1 Clearing the site 3.1.2 Site set out 3.2 Footings 3.3 Walls 3.3.1 Load bearing walls and member connections 3.3.2 Wall components and insulation 3.3.2.1 Building Paper 3.3.2.2 Shaft liner 3.3.2.3 Insulation 3.3.2.4 Internal wall finishes 3.3.2.5 Cladding 3.4 Roof 3.4.1 Roof trusses 3.4.2 Roof components and insulation 3.4.2.1 Pitched roof components 3.4.2.2 Building Paper 3.4.2.3 Insulation 3.4.2.4 Cladding 3.4.3.5 Flashing 3.4.3 Stairs and Windows 3.4.3.1 Stairs 3.4.3.2 Windows

4

Services 4.1 Plumbing 4.2 Electricity

5

References

Construction of Residential Buildings

Introduction: Site Descriptions

Construction of Residential Buildings




1 Introduction : Site Descriptions

Introduction: Site Descriptions

Construction of Residential Buildings

1.1 Houses in Point Cook House 1 Site address

LOT 1111 Saltmarsh Crescent (Saratoga), Point Cook, VIC 3030

Builder

Orbit Homes Pty Ltd

Building Surveyor

Checkpoint

Reg No.

(Left Blank)

Building Permit No.

237310

Use of adjoining land

Residential houses

Approximate size of site

348m2

Description

This house is one storey, has 3 bedrooms, 2 bathrooms and 1 car space. This house uses 2 way waffle slabs as its footings and ground floor structure. It uses timber studs and structural frame for its structural walls and has a masonry veneer cladding. The roofs are supported by softwood timber trusses

House 2 Site address

LOT 863 Solitude Crescent, Point Cook, VIC 3030

Builder

Burbank Homes Pty Ltd

Building Surveyor

Group Foor

Reg No.

DB-0 3333

Building Permit No.

274842016339410

Use of adjoining land

Residential houses

Approximate size of site

454m2

Description

This house is two storeys has 4 bedrooms, 2 bathrooms and 2 car space. This house uses 2 way waffle slabs as its footings and ground floor structure. It uses timber studs and structural frame for its structural walls and has a masonry veneer cladding. The roofs are supported by softwood timber trusses

Introduction: Site Descriptions

Construction of Residential Buildings

1.2 Arve townhouses in Ivanhoe Currently, they are constructing a complex of townhouses in Ivanhoe. Due to its slow construction, my photos comprise a collection of different townhouses.

Site address

229 Banksia St, Ivanhoe, VIC 3030

Developer

Stockland

Architect

MPS architects

Land surveyor

TGM Group

Use of adjoining land

Residential houses

Approximate size of site

1.952 ha

Description

There are 7 main types of townhouses in Ivanhoe.

• Book End Detached 2 storeys, 4 bedrooms, 2 garage spaces • Front Loaded Terrace 01 2 storeys, 4 bedrooms, 2 garage spaces Front Loaded Terrace 02 • 2 storeys, 4 bedrooms, 2 garage spaces • Rear Loaded Terrace 2 storeys, 3 bedrooms, 2 garage spaces Urban Terrace 01 • 2 storeys, 3 bedrooms, 1 garage space • Urban Terrace 02 2 storeys, 3 bedrooms, 2 garage spaces High Density Terrace • 3 storeys, 2 bedrooms, 1 garage space The townhouses uses a timber frame as its structural wall and hebel as its cladding. It has a flat roof with a slight inclination.

Pre construction phase

Construction of Residential Buildings

 

2 Pre-construction phase

Pre construction phase

2.1

Construction of Residential Buildings

Key players involved

Builder Registered with the Victorian Building Authority, they are in charge of managing the construction process of the building. They work closely with the subcontractors and manufacturers to ensure that the building is erected within the stipulated time without compromising the quality. For the townhouses in Ivanhoe, the builders were employed by Stocklands (developer). On the other hand, the houses in Point Cook are sold collectively with the land as a package by Burbank Homes, a volume builder.

Developer The developer mainly buys and develops the land by employing builders, architects, engineers, etc.

Architect In chronological order, the architect is supposed to provide the preliminary design, schematic design, detailed design and lastly construction documentation. During the construction process, they will continue to liase with the builder to ensure that the structure is built according to the drawings. If a problem arises, the drawings would be modified.

Structural Engineer Their main role is to calculate the strains and pressures of different structural components and subsequently design the structure of the building. They will generate engineering drawings which are given to the builder and the architect. These engineering drawings would be included in the drawings under detailed design.

Services Engineer They are in charge of installing and designing the services within the house. These services include stormwater, sewage systems, etc.

Building surveyor The main role of the building surveyor is to ensure that the house is built in accordance to the requirements stated in the Building Code of Australia and the Australian standards. After the completion of the building, the building surveyor would do a round of inspections to ensure that the building is fit for occupancy. If so, he would issue the occupancy permit.

Quantity surveyor Quantity surveyors are often employed for projects that are larger in scale such as the one in Banksia Street. Mainly managing the financial aspect of the project, they ensure that the project is

Pre construction phase

Construction of Residential Buildings

within the budget and are pressured to find cheaper alternatives without compromising the quality.

Frequent checks are made on site to ensure that the builders build according to the contract.

Land surveyor The land surveyor collects data of the detailed features surrounding the site. This would be represented in the form of site plans, that would be used for the planning permit application.

2.2 Building Act

The Building Act is a form of legislation that helps control the building industry. It contains information regarding the requirements for building practitioner’s registration, fire safety for existing buildings, etc. It also provides a platform for stakeholders to settle disputes and offers existing home owners protection against adjoining property.

2.3 Building Regulations It is a set of policies that helps the builder enforce the Building Act, so as to protect the interests of the home owner. It comes in the form of the Building Code of Australia (BCA) and Australian Standards. The BCA is made of different volumes which pertains to different types of buildings.

Each volume contains a list of building requirements that should be followed. This ensures that the minimum levels of community health, safety and amenity are met. For the case of residential construction, volume 2 would be used. At times, the standard building requirements could not be met because of the nature of the house. Thus, in order to continue the construction of the house, performance regulations are used instead. In this scenario, the builder and engineer would submit an alternative design to prove to the council that the design meets the performance expectations.

Pre construction phase

Construction of Residential Buildings

2.4 Drawings The preliminary design is conceptual in nature and is produced based on very general information.

In Point Cook and Banksia street, the land and house are sold collectively as a package by the builders. Thus, in this case, architects would have to gain approval from the builders so as to proceed to the schematic design. Drawings for the schematic design are often drawn more to scale and incorporates materials selection. Feasibility and budget are also taken into consideration.

Models are also constructed. The schematic design is submitted to the planning authorities, engineers, and builders to gain approval. If approved, the detailed design would be generated.

Planning conditions highlighted, specifications and the engineering drawings (structural, mechanical, services) are brought in to this set of architectural drawings. These drawings come in the form of detailed plans, elevations and sections. After once again gaining approval, they proceed to consecration documents. These documents contain very detailed plans, specifications and the budget which is used for tendering.

Attached on the next page is the preliminary design for the Arve townhouses in Ivanhoe.

Pre construction phase

Construction of Residential Buildings

Pre construction phase

Construction of Residential Buildings

2.5 Land survey and site plans This is collection of drawings that analyses the different features of the site. This includes boundaries, features of adjacent buildings.The drawings would be submitted to in the town planning applications so as to attain a planning permit. One example highlighted is a surveyor on windows of neighbouring houses. This is necessary as it the issues of privacy and shadowing are consideration that should be made and done in a accordance to the BCA and the Australian standards.

Attached on the next page is the site plan for the Arve townhouses in Ivanhoe.

Pre construction phase

Construction of Residential Buildings

Pre construction phase

Construction of Residential Buildings

2.6 Soil tests This is a crucial step in the pre-construction phase which involves a geotechnical engineer testing the reactivity and quality of the soil. This soil test measures the likeliness of the soil movement expansion and contraction which could impact the stability of the house. After the soil test is being conducted, the results would be discussed in a soil report. The soil report would contain information regarding the soil layers, nature and the classification. This classification is based on the reactivity of soil. (Figure 1)

Figure 1 Soil classification Taken from AS 2870

For Class A to E soils (Figure 1), the design of the footings could follow the standard design of the footings set out in the Standards. If the soil is of class P, teh standard design of the footings could not be followed. Instead, a structural engineers is engaged to specifically design the footings to fit the house.

Pre construction phase

Construction of Residential Buildings

2.7 Permits

2.7.1 Planning permit A planning permit gives the individual the license to develop the piece of land. This could be obtained from the city of Melbourne.

Applying for a planning permit requires the following details:

• • • • • • •

Details of the land Plan of existing land Existing conditions Applicant and owner details Plan showing the details and layout of the proposed building Current metropolitan planning levy certificate etc

2.7.2 Building Permit According to the website of the City of Melbourne, in order to commence any form of construction work, a building permit from the local council is required. This could also be issued by a private building surveyor when the project plans comply with the Building Code of Australia and the Australian standards.

To obtain the building permit, the following are required: • Form 1 application for a Building Permit • 3 copies of architectural drawings (Plan, Elevation, sectional drawings under Detailed design for each floor) • 3 copies of material and construction specifications • 3 copies of structural engineering drawings and calculations • 3 copies of geotechnical reports • Energy report • Details of registered practitioners (Architects and Builders) • Approximate construction costs • Title of ownership • Building Contracts • Hoarding permits • Site investigation report • Statement of intended use • Subdivision Plan • Statement of home warranty insurance • Permit Fees

Pre construction phase

Construction of Residential Buildings

2.8 Termite control Before the construction of any building, termite treatments could be implemented to meet the Australian Standards 3660-1 and to prevent infestation that could affect the construction process and the long term durability of the home. With reference to Right Pest Control website, private pest control companies are engaged where they would install chemical barriers, reticulation pipe, pipe collars.

2.9 Overall process (simplified)

Houses in Point Cook

Arve townhouses in Ivanhoe

1. Site is acquired. The land is bought by the volume builder (Burbank Homes) 2. Preliminary drawings are provided by the architect.

3. A client purchases a land and home package.

4. The land is surveyed and soil tests are conducted.

5. Application for Planning Permit 6. Application of Building Permit 7. Construction 8. Settlement and completion

1. Site is acquired.The land was acquired by the developer (Stockland) 2. Preliminary drawings are provided by the architect 3. The land is surveyed and soil tests are conducted.

4. Application for Planning Permit 5. Application of Building Permit 6. Tender 7. Construction 8. Sales and marketing 9. Settlement and completion

Pre construction phase

Construction of Residential Buildings

During the pre-construction phase, there is a need to create a timeline or a schedule showing when the different tasks would be carried out. This gives a rough estimate to when the project would be completed and helps ensure that there would be no clashes when installing certain components that could not be done simultaneously. A generic schedule has been attached below.

Figure 2 Bar chart Taken from ownerbuilder.com

Construction phase

Construction of Residential Buildings

3 Construction Phase

Construction phase

3.1

Site Preparation

3.1.1

Clearing the site

Construction of Residential Buildings

Across the houses for this assignment, two distinct types of excavation could be observed, mainly bulk and trench excavation.

Previously, the land in Point Cooke was empty, hence bulk excavation was employed. This involves a tracked loader adding or removing rocks and soil to form an even area for building.

(Photo 1) This is carried out by the excavation contractor and done according to the soil report.

Soil delivered to site by excavation contractor Tracked loader evening out the ground level Added soil

Photo 1 Bulk excavation

The townhouses in Banksia Street used to be occupied by Bellfield Primary School and Banksia La Trobe Secondary College.Thus trench excavation was engaged to remove the substructures of the previous schools to make way for for the installation of footings for the townhouses.

3.1.2

Site set out

This refers to marking out the perimeter of the building with lime. Allowances are considered to fit the width of the footings. (Photo 2)

tracked loader

Soil and rocks removed from house perimeter

pipes within the perimeter: sewer site set out with lime pipes outside the perimeter: storm water Photo 2 Bulk excavation and site set out

Construction phase

3.2

Construction of Residential Buildings

Footings

Footings, part of the substructure, transfers the load from the super-structure to the foundation. These loads often include dead, live and dynamic loads. Dead loads refer to the weight of the ceiling, self weight of structural walls, etc and live loads refer to the weight of moving objects and people.

The choice of footings is up to the contractor. Some factors that contribute to this decision could be cost, time, availability of materials and the contractor’s familiarity to the method used.

In Point Cooke, waffle slabs are chosen. They are classified under integrated footings and is a form of reinforced concrete slab that has closely spaced ribs on the underside. It involves polystyrene void formers being laid on a levelled site and formwork surrounding the perimeter of the house. (Photo 3). Without the need to dig trenches, cost and time for site preparation is reduced.

Photo 3 shows the different components of the waffle slab.

Formwork Made of timber, they are temporary moulds built along the perimeter of the house to hold the liquid concrete in place for the curing process.

This could be because of its smooth finish, low labour cost and its ability to be reused and recycled several times8. This is done in-situ.

Reinforcement bar chairs They hold reinforcing bars Placed under the reinforcing bars to hold them up to the middle of the concrete slab, they prevent the bars from rusting and failing.

Therefore ensuring maximum and efficient tensioning.

These bar chairs are manufactured in factories and assembled in situ.

Photo 3 Preparation for waffle slabs Polythene Vapour Membrane It protects the poured cement from the moisture released from the soil underneath, which could potentially reduce the stability of the foundation. This sheet is assembled in situ.

Reinforcing Steel Bars They are long steel bars used with concrete to form reinforced concrete. With concrete being weak in tension and steel being strong in tension, steel bars are added to increase the tensile strength of concrete foundation7 via posttensioning3. Thus when a load is added, chances of cracking decreases, which increases the stability of the foundation. These bars are assembled in-situ.

Polystyrene Void Formers They act as a mould to produce a concrete slab with a ‘grid’ layout, resulting in the underside mimicking a waffle10. These boxes are manufactured are made in factories and assembled in-situ.

Construction phase

Construction of Residential Buildings

Waffle slab footings often follow a standard set of measurements which are indicated in Sketch 1.

Sketch 1 Waffle slab diagram with standard measurements (mm)

In order to determine the footing specifications, information such as site class (refer to soil report) and type of construction is needed. I was unable to obtain the soil report for this site, thus assuming that it has a site class of H1 (similar to all the houses in Point Cook) the specifications are highlighted below.

Thus the specifications for the house in Point Cooke is as follows :

Beam reinforcement: • Beam depth: 460mm • Edge beam • Bar alternative: 3 N16- N steel grade with 16mm diameter of bars • Internal beam: N16- N steel grade with 16mm diameter of bars • Slab mesh: • SL82- square,low ductility steel,8mm diameters with 200mm spacing between bars (knowing that slab length <20m ) Taken from AS 2870-2011

After carrying out a slump test to ensure the workability the poured concrete, concrete is added via the drop chute. The freshly poured concrete is run over a vibrator which removes the existing air bubbles in the concrete. (Photo 4) This improves the bond between the concrete and the reinforcements and increases the strength and density of the slab. This increase the overall durability of the reinforced concrete slab.

Photo 4 Use of the vibrator on the surface

Afterwards, curing occurs which involves retaining moisture and reducing the rate of evaporation to increase the compressive strength of the slab as well as to prevent cracking

Construction phase

Construction of Residential Buildings

3.3 Walls 3.3.1 Load-bearing walls and member connections Structural in nature, load-bearing walls transfer loads from the superstructure towards the footings.

These loads include live, dead and lateral loads. Lateral loads are wind forces that may cause the overturning and uplifting of houses.(Ching, 2014) For the houses in Point Cook and Banksia street, timber frames were used. This is because they are renewable resources, environmentally-friendly and readily available.

Depending on the client, these frames could be either made precast or assembled on site. In Point Cook, timber members are assembled insitu which is possibly because of its smaller scale of construction. On the other hand, in Banksia street, the large scale construction could be one of the reasons for timber frames being produced off site.

Photo 5 Point Cook- Timber members delivered to site and assembled on site

Photo 6 Banksia Street- Timber frames made in factories delivered to site

Timber frames are designed by the structural engineer. They are done according to the guidelines specified in the Australian standards, specifically AS1684.4-2010. The sizes of the timber members are generally derived from the plans of the house (type of roofs, opening widths,etc) and the type of timber the contractor is planning to use(seasoned or unseasoned, F or MGP).

Taken from AS1684.4-2010

Construction phase

Construction of Residential Buildings

Bracing helps resist lateral forces such as wind, thus is crucial in maintain the overall stability of the house. It could be permanent or temporary.

Permanent bracing helps ensure the long-term stability of a house.They are often placed at the corners (areas most vulnerable to lateral forces) There are two types of bracing, diagonal bracing and sheet bracing. Diagonal bracing is made of two steel members that are crossed. They resist wind forces by having one acting in compression and the other in tension, depending on the line of action. (Sketch 2) On the other hand, sheet bracing comes in the form of a large piece of plywood that has its perimeter nailed to the timber frame. They act as and additional layer of wall so as to resist wind loads.

Temporary bracing comes in the forms of props. It supports the building for a short period of time and is removed once the building is able to stand by itself.

The different parts of a timber frame and the load path diagram are shown below (Photo 7,8 and sketch 3) Lintel They are made of timber with higher stress gradings so as to better withstand the weight above openings. Unlike the rest, The larger surface of the timber member faces the exterior which gives them a higher moment of inertia.

(Sketch 3). This allows the forces in there vertical direction to be transferred more efficiently to the footings.

Full stud They are vertical framing members that carry static loads, resists lateral load and outline the shape of the building.

Cross Bracing (metal) Jack stud Jamb stud Made of two timber members so as to more effectively transfer the load from the lintel, around the opening to the bottom plate

Load

Sketch 2 Lintel orientation

Jack stud

Sheet Bracing (plywood)

Lintel trimmer

Sill trimmer

Nogging It works similar to a jamb stud but instead of using 4 timber studs, shorter blocks are used to reduce cost and are only put at critical areas.

Bottom plate They are beams located at the base of the timber frames. They help transfer the load from the vertical timber studs to the footings. They also ease the nailing of vertical timber studs to the concrete slab.

Photo 7 Wall framing components

Dead and Live load

Wind

Lintel (for the garage)

Sketch 3 Load Path Diagram

Temporary bracing

compression tension

Photo 8 Wall framing components

Construction phase

Construction of Residential Buildings

Member connections play an important role in stabilising the structure. They come in different forms to cater to different situations. The following photos will show how different types of connections are used and show different cases of timber frame.

Edge detailing The addition timber blocks at the edge prevents the studs at the edge from shearing and bending.

The studs at the edge are most prone to failure because it is subjected to winds coming towards its side and front

Based on the moment of inertia, many of the studs have an â&#x20AC;&#x2DC;on edgeâ&#x20AC;&#x2122; arrangement, which helps resist lateral forces (wind). (Sketch 4) It also increases the thickness of the wall so as accommodate insulation components.

Metal straps They are nailed in so as to connect the lintel to the timber studs.

The corners use studs with a square cross-section to avoid lateral forces coming from perpendicular directions, based on moment of inertia. (Sketch 5)

Wind Sketch 4 Stud orientation

Wind

Special metal straps are used to attach the meter boxes to the timber frames.

Wind Sketch 5 Corner stud shape

The bottom part of this corner stud is made of metal so as to to more effectively connect and transfer the load from above to the footings. Extra consideration was taken because there no other studs at the front or the right to support the weight of the upper storey

Shear ring It connects the metal to the timber. This increases the bearing area of timber when bolted into metal components

Photo 9 Timber frames and member connections

Truss connector plates The timber members are connected by â&#x20AC;&#x2DC;driving' nails into the plates on the studs. This reduces the likelihood of splitting.

Tensioning clip It allows builders to alter the amount of tension by tightening the screw.

Hoop iron bracing They are long diagonal metal straps that forms the main component for bracing.

Photo 11 Stud orientation

Nogging

Timber stud Bottom plate Photo 10 Bracing members

Concealed beam ties One possible connector used here is concealed metal beam ties between studs and sole plates. They are strong and embedded within the timber.

(Gibson, 2016) This protects the connection from moisture thus is less prone to rusting and less likely to fail (Sketch 6)

Bolts

Sketch 6 Concealed beam ties

Construction phase

Construction of Residential Buildings

For the structural frames, a variety of timbers and other beams are being used according to their function. This would be illustrated in the following photos below â&#x20AC;Š Termite treated timber These timber members are treated with chemicals so as to resist a termite attack. They are placed at primary load bearing areas within the house. This is because,these load bearing members could not be easily replaced with new timber studs when the house is under a termite attack

Hot-rolled steel beams and studs They are used as lintels and corner timber studs. This is because these areas are comparatively more load bearing than the other areas. Thus stronger and thicker materials such as hot rolled steel is used instead of the standard timber studs.

Concealed beam ties could have been used to join the cross section of the particle board to the wall frame.

Metal straps could have been used for this butt joint which connects the top plate of the wall framing to the floor bearers of the upper storey.

Particle board Particle boards are used in the floor bearers of the upper storey for convenience.

As particle board is a form of engineered timber, different dimensions of beams could be easily obtained. In this case, beams with a long cross section is required so as to increase its moment of inertia. To achieve this cross section, it would be difficult to use regular hardwood timber members

Termite treated timber Again, termite-treated timber is used. In this case, it is very difficult to replace the openings around the stairs without having to demolish the house.

Construction phase

Construction of Residential Buildings

3.3.2 Wall components and insulation Wall components vary according to the builder, facings and design of the house, etc. The wall components highlighted is an isolated case that may not be representative of all the houses in Melbourne.

For the townhouses in Banksia street, the wall components are illustrated below. (Sketch7-8)

Plasterboard Minimum 25mm air gap Reflective insulation Bulk insulation

Timber stud (part of timber wall frame)

Building paper

3.3.2.1 Building paper Metal bracket (to attach Hebel to timber frame)

After the timber frames are installed, building paper is immediately laid on the outer surface of the frames. They protect the Hebelframes from weathering which could potentially cause moulding and expansion. In addition, they have a reflective surface that faces the interior of the house, which helps reflect radiant heat back into the house.

EXTERIOR

INTERIOR

For the corner houses whose rear wall is exposed, building paper is laid. However, for the houses Sketch 7 whose rear wall is attached to another house, building paper is not installed as the timber frames Rear wall of corner town houses that is exposed are less prone to weathering. This saves cost.(Photo 11)

Plasterboard Minimum 25mm air gap Reflective insulation Timber stud (part of timber wall frame)

Bulk insulation Shaft liner Reflective insulation

Building paper

Minimum 25mm airinstalled gap at the Plasterboard

exposed wall

Timber stud (part of timber wall frame)

Building paper not installed at the nonexposed wall

Bulk insulation INTERIOR

INTERIOR OF ADJACENT HOUSE

Sketch 8 Rear walls of houses in the middle. These walls are attached to the rear walls of the Photo 11 adjacent townhouse.

Interior of a corner house

Construction phase

Construction of Residential Buildings

3.3.2.2 Shaft liner For the houses whose rear walls are attached to another house, a shaft liner panel is being installed instead. They are 25mm thick sheets made of glass fibre reinforced gypsum. Being fire graded and containing acoustic insulation characteristics, they prevent the fast spread of fire and reduces the transmission of noise to another house. (Photo 12-13)

Shaft-liner

Shaft-liner

Photo 12 Shaft-liner on non-exposed wall

Photo 13 Shaft-liner between attached town-houses

After the shaft liners are fixed in place, the inner wall and cladding could be assembled simultaneously.

3.3.2.3 Insulation For the inner wall, insulation is installed first. (Photo 14) Insulation reduces the transmission of heat, that comes in the form of convection, conduction and radiation. The townhouses in Banksia Street uses a composite material, a combination of bulk and reflective insulation. Reflective insulation comes in the form of a sheet with a shiny aluminium foil surface. The foil faces the interior so as to reflect radiant heat back into the house. There is a 25mm air gap next to the foil so as to further facilitate thermal insulation. Bulk insulation is made of foam consisting of tiny air pockets. The air pockets acts as a barrier against heat entering by conduction and convection.

Bulk insulation Reflective insulation

Photo 14 Insulation at roof (I was unable to get a good photo of the wall insulation components, thus I used the photo of the roof insulation which in this case is rather similar because a flat slightly inclined roof is used instead of a truss roof. )

Construction phase

Construction of Residential Buildings

3.3.2.4 Internal wall finishes For the townhouses in Banksia Street, 10mm standard (RE) plasterboards are used for the wall finishes. They are nailed on to the timber wall framing with plasterboard screws and acrylic stud adhesive. The ends are slightly recessed such that when the joints are concealed with tape, an even surface could be achieved. After the taping the joints, several coats are added so as to even out the surface. During this process, the surface is constantly sanded. (Photo 15)

Plasterboard panel Tape coat over plasterboard tape Tape coat over plaster board screws Skirting Plasterboard tape

Photo 15 Plaster boards for the internal wall

Diagram 1 Plasterboard finishes diagram, screenshoted from Gyprock youtube video on plasterboard assemblage

Tape coat over Plasterboard tape

Wet area resistant plasterboard

Services

Photo 16 Plasterboard in bathroom

For the bathrooms, a 10mm wet area resistant (WR) plasterboard is being used instead. These plasterboards are treated with a spray or a varnish coat that resists water. This protects the timber frames from water which could prevent moulding and failing.

(Photo 16)

Construction phase

Construction of Residential Buildings

3.3.2.5 Cladding For cladding, Hebel is used. Hebel is a form of autoclave aerated concrete. It is lightweight and contains 80% air which increases heat and sound insulation. They are also fire-rated, which is crucial in preventing the fast spread of fire to neighbouring townhouses. They are manufactured in factories and delivered to site in standard sizes. Their size and shape could be altered on site if changes are to be made.

Building paper Hebel Head and Base Angles Hebel is nailed into these stainless steel angles so as to attach Hebel to the timber frames.

Holes are being made in the Hebel to accommodate for services.

Nails drilled into Hebel onto head and base angles

Hebel mortar is mixed on site and is used to seal the joints between Hebel panels.

Photo 17 Hebel used for cladding

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Construction of Residential Buildings

3.4 Roof

3.4.1 Roof trusses One of the houses in Point Cook and all the Arve townhouses in Ivanhoe use timber roof trusses.

Roof trusses are load bearing structures that use the shape of triangles to effectively transport the loads from the roof to the the external walls.

For the houses in Point Cook, an A-type roof truss is being used. (Photo 18). This is a roof is commonly used and has an approximate truss span of 9m which is divided into 3 equal lengths.

Sketch 9 would show the different components of an A-type roof.

Photo 18 Roof truss in Point Cook

Apex

Top chord

Truss connector plates (discussed earlier ) Web Heel

Overhang

Bottom chord Intentional gap

External wall

Internal wall

Sketch 9 A-type roof

The truss roof design must adhere to the following requirements set out in the Australian standards. Some of these requirements include rood having a maximum pitch of 45 degrees, a maximum truss span of 16m,etc.

Construction phase

Construction of Residential Buildings

For the Arve townhouses in Ivanhoe, flat trusses are being used. (Photo 19). Unlike the A-type truss, it has a parallel top and bottom chord. Though less efficient in resisting wind, live and dead loads, this truss type was chosen for aesthetic reasons. Sketch 10 would show the different components of a flat truss.

Photo 19 Roof truss in Point Cook

Top chord Truss connector plates (discussed earlier)

Web Bottom chord Intentional gap

External wall Internal wall

Sketch 10 Flat truss

Timber members are more likely to fail in bending rather than compression and tension. This theory is used in the mechanism and the design of the roof truss. Timber roof trusses resists wind loads, gravity dead and live loads, and roof loads by timber members acting in compression and tension. Diagram 2 and 3 would show how trusses resist the different loads

Members acting in compression : 1, 2, 3 and 6 Members action in tension : 4, 5 and 7 1

3

5

4

2 6

7

Diagram 2 Resistance to gravity dead and live loads

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Construction of Residential Buildings

Members acting in tension : 1, 2, 3 and 6 Members action in compression : 4, 5 and 7 1

3

4

5

2 6

Diagram 3 Resistance to wind uplift

There is a need to put a gap between the non-load bearing internal walls and the truss. This is because the truss functions by transferring dead, live, and wind loads towards the external load bearing walls only. This is brought about by the timber members acting in tension and compression. If the truss is joined to the internal non-load bearing walls, the truss would function as a beam, thus bottom chord would undergo bending instead to resist the force.

As its easier for timber members to fail by bending, the roof loads should not be directed towards the inner walls. Therefore, it is necessary to put a gap between the roof truss and the non-load bearing internal walls.

Diagram 4 Load path diagram showing the gap between the load bearing internal wall and roof truss

These trusses are often fabricated in factories and is subsequently delivered to site for assemblage. This allows the manufacturers to camber the trusses. Cambering refers to forcing an upward bend in the top chords. Thus when the load applies a downward force on the truss, the top chord would flatten and bend to take up the straight shape it was supposed to have.(Diagram 5)

Initial shape of pre cambered timber Final shape of pre cambered timber after forces are directed to the roof Diagram 5 Load path diagram showing the gap between the load bearing internal wall and roof truss

Construction phase

Construction of Residential Buildings

3.4.2 Roof components and cladding

Roofing components vary according to the builder, design of the house, etc. The roofing components highlighted is an isolated case that may not be representative of all the houses in Melbourne.

For one of the houses in Point Cook who uses a pitched roof instead of a roof truss, a metal roof sheeting is used as its cladding. This form of cladding has a corrugated surface, whose direction is perpendicular to the the eaves gutter, which lines the perimeter of the roof. Therefore, it is able to effectively facilitate the transport of stormwater into the eaves gutter for stormwater collection.

(Photo 20)

Metal roof sheeting Incomplete installation of eaves gutter for flashing

Direction of corrugated metal roof sheeting

Photo 19 Metal roof sheeting

The different components of the roof is shown in sketch 11.

Metal roof sheeting

Building paper

Purlin

Rafter Reflective insulation

Sketch 11 Roofing components for metal roof sheeting

Construction phase

Construction of Residential Buildings

3.4.2.1 Pitched roof components

Pitched roofs is a conventional roofing method that uses purlins and rafters to withstand the load.

Initially, the rafters and and purlins are assembled on site to form the main room structure. Rafters are beams positioned vertically on the sloping sides of the roof and spaced at regular intervals.

Purlins too are beams but are positioned horizontally and perpendicular to the rafters. They too are spaced at regular intervals. These components form the base for sheathing and cladding. Unlike roof trusses, pitched roofs are assembled entirely in situ, thus is more labour intensive and requires more precision.

Bracing could be added to these roofs to add stability.

The installation of a timber roof frame allows the interior and exterior side of the roof to be worked on simultaneously. â&#x20AC;¨

3.4.2.2 Building Paper After the timber roof frames are installed, building paper is installed on top of the purlins. They protect the timber rafters and purlins from weathering and mould. If this is not carried out, the timber rafters and purlins are succeptible to early failure. Building paper also has insulating properties. the reflective surface of the building paper faces the interior of the house so as to reflect radiant heat back into the house (Photo 20).

Reflective surface of building paper.

Photo 20 Building paper attached to purlins

3.4.2.3 Reflective insulation Afterwards, reflective insulation is assembled under the rafters. Similar to wall insulation, reflective insulation reflects heat back in to the house. For it to function efficiently, a 25mm gap is required between the reflective surface and the particleboard attached to the roof.

Construction phase

Construction of Residential Buildings

3.4.2.4 Cladding Simultaneously, the cladding, in this case, metal sheet roofing could be added on top of the building paper. The metal sheet roofing is often screwed into the purlins and through the building paper. (Diagram 6)

Diagram 6 Screwing the metal sheet roofing onto the timber members Taken from the â&#x20AC;&#x153;Roof framing and claddingâ&#x20AC;&#x2122; lecture notes

3.4.2.5 Flashing To facilitate the movement of water from the roof to the stormwater pipes, an eaves gutter, a form of flashing, is being used. The eaves gutter and the other roofing components are assembled simultaneously. (Photo 21)

Eaves gutter

Metal straps are used to attach the eaves gutter to the

Photo 21 Eaves gutter assemblage

Construction phase

Construction of Residential Buildings

Sketch 12 shows how the eaves gutter would be assembled into.

Eaves drip It is a metal strip attached at the edges of the roof below the building paper . It supports the roof cladding, covers small gaps between the building paper and the fascia,and prevents water from entering the airspace which can destroy the insulation and destroy the structural framing

Metal roof sheeting Building paper

Fascia They are long boards lined and attached to the bottom edge of the roof and the sofit. It supports the weight of the bottom tiles and gutter.

Eaves gutter It collects stormwater from the metal roof sheeting and transfers it to the stormwater pipes.

Sofit It is the covering on the underside of the roof where it meets the walls. It is used to cover the rafter beams to meet aesthetic needs and to protect rafters from rain

Interior

Exterior Sketch 12 Eaves gutter

Sofit vent They are openings in the sofit. They allow air to enter and exit the attic which prevents overheating and moisture that can cause the rusting(steel) and moulding (timber) of rafters and sheathing

Construction phase

Construction of Residential Buildings

3.5 Stairs and Windows

3.5.1 Stairs

For the Arve townhouses in Ivanhoe, the winder stairs were being used. (Diagram 7) Because of the plan of the townhouse, I was unable to take a good photo of these stairs. (Photo 22) The winder has two flights of stairs. The shorter flight of stairs in the winder stair design reduces the distance to which a person could fall across to. Therefore, the winder stairs are often preferred over straight stairs. Other factors that influence the design of the stairs is the required length of the tread and risers which is emphasised in the Building regulations. The treads should range from 115mm to 190mm whereas the risers should range from 240mm to 355mm. (Diagram 8)

Diagram 7 Winder stairs Taken from 'Stairs and Windows' lecture

Handrail Riser Tread

Skirting board Photo 22 Bottom of the winder stairs

Diagram 8 Stair components Taken from 'Stairs and Windows' lecture notes

Construction phase

Construction of Residential Buildings

3.5.2 Windows To be fit for occupancy, the requirements for natural lighting and ventilation must be met. Thus, windows are necessary.

Most of the windows used for the houses in Point Cook and the Arve townhouses in Ivanhoe are made of aluminium frames. This reduces the need for regular maintenance.

The windows are mostly single glazed and made of toughened glass. Toughened glass is stronger than usual glass and would break into small pieces with blunt edges. This protects the occupants from getting hurt.

The toughened glass is fitted into the aluminium frames in factories and brought to site to be assembled. They are often nailed into the sill trimmers and the lintels. (Photo 23 and 24)

Aluminium frames of window rest directly below the lintel

Lintel Black covering over aluminium frames to offer protection against rough construction work Nailed to vertical studs that are covered with sheet bracing

Photo 23 Aluminium window frames for the house in Point Cooke

â&#x20AC;Š Unlike the houses in Point Cook, the window frames do not rest directly on top of the sill trimmer or directly below the lintel. Instead it protrudes out of the timber frames

Metal connector to attach sill trimmer to window.

Photo 24 Aluminium window frames for Arve townhouses in Ivanhoe

Services

Construction of Residential Buildings

4 Services

Services

4

Construction of Residential Buildings

Services

4.1 Plumbing

Plumbing covers stormwater, sewer, hot and cold water supply, gas,etc.

Initially, site visits and inspections are carried out to identify the underground positions of these services. To confirm the location of these services, Dial Before You Dig should be contacted.

For stormwater services, the legal point of discharge is crucial in directing stormwater from the roof or the ground to the neighborhood’s collective stormwater tank. (Photo 1)This is often located on the streets and near the kerbs. To use this legal point of discharge, an application must be made to the council.

Photo 1 Legal point of discharge taken from the ‘Services’ lecture

For the sewer, information regarding the sewer configuration within the property could be acquired from the asset authority. After understanding the sewage system of the area, applications should be made to the council to request a modification to the sewer’s underground pipework, so as to accommodate the sewage of the new property.

Th plumbing services must be roughed in before the construction of the footings. This involves the plumber setting out the drainage and installing the sewer and stormwater pipes to the required areas within the site. (Photo 2) Here, the architectural working drawings is heavily referenced to, so as to ensure that the pipes rise up through the slab at the correct position for toilets, kitchens, etc.

(Photo 3) Stormwater pipes are often located at the perimeter of the house so as to collect stormwater from the gutter on the roof

Services

Construction of Residential Buildings

Photo 2 Storm water and sewage pipes being roughed in Sewage pipes

Stormwater pipes (green)

Photo 3 Storm water and sewage pipes being embedded into the concrete slab Sewage pipes (black)

Stormwater pipes (green)

For hot and cold water supply, rough ins are also made into timber wall frames before the main insulation components and cladding are added. This involves drilling holes into the timber frames (wall and upper floor) so as to run and install the water pipes.(Photo 4 and 5) Building paper is laid on the frames before pipe installation so as to protect the surface of the rubber pipes

Holes made in the timber wall frames to accommodate the pipes

Photo 4 Close shot of rough ins in the timber frame

Services

Construction of Residential Buildings

Pipes are fixed to the timber frames by metal connectors to prevent them from drooping.

This could allow a continuous and unrestricted flow of water.

Hot and cold water supply for the upper storey

Holes made in the timber wall frames to accommodate the pipes Photo 5 Rough ins in the timber frame

In photo 6, the hot and cold water piping protrudes out of the house to connect to the water tank that has yet to be installed. The building paper is easily torn. To protect its insulating properties, the gaps between the building paper and the pipes are taped. This is also done to secure the position of the pipes.

Here the surface of the pipes would be subjected to degradation if not covered and exposed to rain, causing the hot and cold water service system to fail even before occupancy.

Supposed position of water tank

Water pipes directing water towards the interior of the house

This water tank also collects stormwater. This is necessary because the Arve townhouses in Ivanhoe lack gardens spaces.

Water pipes Stormwater pipe Photo 6 Rough ins in the timber frame.

Here, the use of timber frames as the structural wall is especially advantageous. The gaps between the timber studs and beams allow the pipes to run smoothly through the structure. In addition, the ability to drill through the timber on site allows the plumber to flexibly alter the position of the pipes if there is a change.

Services

Construction of Residential Buildings

The gas meter is located on the exterior of the house. It measures and directs the flow of gas to hot water services, cooktops, etc. The outlet side would be connected to the following services by the plumber.

Photo 7 Gas meter that has been partially installed

4.2 Electricity The electrical components and the meter boxes of the house has to be installed by a qualified and licensed electrician. This must be done in accordance to the Electricity Safety Act and Electrical Safety (Installations) Regulations.

Prior to installation, the electrician would need the architectâ&#x20AC;&#x2122;s working drawings. This would allow him to factor in the position of the other services when installing the electrical components. Thus prevents clashes from occurring. The working drawings would also include position of light switches and power sockets, which would be useful in determining the location of certain wires.

For the houses in Point Cook, the electric mains would be brought into the house through underground mains (Photo 8) that would connect to an electric meter (Photo 9) and a sub board.

The sub board would then split up the electricity to power circuits, lighting circuits, isolation switch etc.

Photo 8 Underground mains for electricity

Services

Construction of Residential Buildings

Initially, a temporary electricity supply was attached to the building site. This generates energy for the machinery used during the construction process. (Photo 9)

Photo 9 Power generator on site

There are two main stages for electrical installation in the house, electrical rough ins and electrical fix off.

Similar to plumbing, electrical rough ins involve the installation of meter boxes and electrical circuits into the structural walls, which happens before major insulation components and cladding are added. Holes would be drilled into the timber frames to fit these circuits which would eventually run through the walls and the floors of the upper storey.

Brackets used to attach Hebel (cladding) to the walls

Meter box

Building paper

Photo 10 Meter box installation during rough in stage

Services

Construction of Residential Buildings

Electrical wires

Holes drilled into timber farming to accomodate the electrical wires

Photo 11 Rough in works for electrical components (Taken from the â&#x20AC;&#x2DC;Servicesâ&#x20AC;&#x2122; lecture notes)

Electric fix off occurs when the plasterboard had been added to the walls but before painting.

Holes are made into the plasterboard for the wires to come through. In photo 3, the electrician is responsible for connecting all the lighting outlets, powerpoint and other electrical components.

(Photo 12) During the electric fix off process, the sub board is also installed onto the plasterboard before painting. (Photo 13)

Photo 12 Electric fix off in the bathroom for light switch

Photo 13 Sub board on plasterboard

After completing the electrical installations, the electrician has to issue a certificate of compliance which would be presented to the building surveyor.

References

Construction of Residential Buildings

5 References

References

Construction of Residential Buildings

References • Devine, Aidan. "The Development Process – Step By Step: 20/10/2011". Your Investment Property. N.p., 2017. Web. 7 Mar. 2017.

• "Planning And Building Services - City Of Melbourne". Melbourne.vic.gov.au. N.p., 2017. Web. 7 Mar. 2017.

• "Planning And Building Services - City Of Melbourne". Melbourne.vic.gov.au. N.p., 2017. Web. 7 Mar. 2017.

• "Soil Testing And Geotechnical Reports". BUILD. N.p., 2017. Web. 8 Mar. 2017.

• "Pre-Construction Termite Control Melbourne | Right Pest Control". Right Pest Control. N.p., 2017. Web. 8 Mar. 2017.

• "Former School Sites". Banyule.vic.gov.au. N.p., 2017. Web. 18 Apr. 2017.

• Wilkie, G. (2011) Building Your Own Home. Australia : New Holland Publishers. 18 Apr. 2017.

Images • "Accurate scheduling is key to better manage your home building or remodeling project".OwnerBuilder. Taken from http://www.ownerbuilder.org/scheduling.shtml 21 April 2017