CONSTRUCTION ANALYSIS A S S I G N M E N T
03
ABPL 20033
JEREMY BONWICK
[697718] TUTORIAL 01 . MIA WILLEMSEN
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STRUCTURAL SYSTEMS: BELOW GROUND CONSTRUCTION ANALYSIS [ABPL20033] ASSIGNMENT 03
JEREMY BONWICK [697718] TUTORIAL 01 MIA WILLEMSEN
The design of the Kew House was heavily influenced by existing conditions of the site, primarily the slope from the back of the site down to the front — approximately a 7 meter fall. The ramification is that the living areas of the home are placed upstairs to be flush with the backyard space but enjoy an elevated position on the north facade, looking down towards the Yarra River. The below ground structure allows for the level change to be flush at the front and rear, with the concrete blockwork retaining wall holding back the cut earth on the southern wall of the garage. The concrete blocks are strong in compression to support the loads from the floors above and are reinforced with N16 (normal-ductility, 16mm bars) steel bars to improve its lateral stability to withstand the forces from the earth when it is filled back in. The Agi pipe at the bottom of the trench also works to help the structural performance of the retaining wall, moving water away and not allowing it to sit against the wall which increase the pressure on the blockwork wall. The land surveyors report on the soil type of the site also influenced the properties that the below ground support needed, the soil type being a silty clay needed to be supplemented with a bed of compacted sand between the ribs of the slab and free draining backfill behind the retaining wall to assist in water draining to the agi pip to be directed away from the wall.
STRUCTURAL SYSTEMS BELOW GROUND
Pad Footing
Pad Footings are used to support the southern end of the dwelling where it is above ground, the substructure is formed from 200m deep concrete pad footings, 600mm below the ground level, poured with a diameter of 350mm on a the naturally silty clay soil of the site.
Strip Footings
The western edge of the back half of the house has a strip footing to support the edge of the dwelling. The concrete is 450mm wide and 600mm deep, reinforced with 4-L12TM (4 bars of low ductility 1mm, 200m spaced trench mesh) which is places at the top and bottom. The strip footing directly support the blockwork placed on top.
Raft Slab
The main slab on the site is that for the basement/ground floor, which is engineered with 300mm wide, 500mm deep ribs running through the center and the same dimensions on the edge ribs, with 100mm of cover between them and larger edge on the southern side, with a 2100mm wide and 500mm deep edge beam.
Blockwork retaining wall
The masonry varies across the site, but for the purposes a large-format, hardy concrete blockwork was chosen. The blockwork is reinforced through its hollow cores with 3 bars of N16 (normal-ductility, 16mm diameter) reenforcement running vertically and N16 bars every 400mms horizontally with concrete poured to fill the void around the bars.
Stumps
A 100x100mm reinforced concrete stump sits on the pad footing and carries the loads from the
HORIZONTAL VERTICAL
The site is cut and filled before the slab is laid to create the footings for the foundations (in this case, the slab) to sit upon
600mm deep concrete pad footings and in-situ poured concrete stumps partially submerged below ground level.
Although the concrete slab is one solid mass it still functions with primary and secondary structure characteristics. The 500mm deep, 300mm wide ribs through the middle of the slab act as a secondary structure and the edge beams act as primary structure. Site slopes from back to front creating a level change which means the ground level garage becomes effectively a basement. Steel reenforcement bars in the slab; 3-L12TM (3 bears of 1mm diameter, 200mm spaced trench mesh) at the base of the ribs and RL1218 (rectangular, low ductility, 12mm diameter, 180mm spaced) mesh over the top.
Because of the site’s slope, blockwork retaining walls are used to hold back the earth below the ground level.
Starter bars interlock the horizontal and vertical systems
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Blockwork is set into the concrete slab with a set-down or rebate to create the right levels for the finished floor above as the blocks are fixed heights.
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STRUCTURAL SYSTEMS: ABOVE GROUND CONSTRUCTION ANALYSIS [ABPL20033] ASSIGNMENT 03
JEREMY BONWICK [697718] TUTORIAL 01 MIA WILLEMSEN
The above ground structure defines the exterior form of the building as much as it encloses the interior space. The cantilever over the garage door is supported by the vertical and horizontal supports on the ground floor, withstanding the added loads with an engineered steel parallel flange channel supporting the suspended floor beam with a square hollow section and stiffener plates added where the loads will be greatest. The cantilever has to appear weightless, so the structure needed to be effective in supporting the projection and maintaining a relatively small profile to enhance the ‘magic’ of the overhang. Although the structure describes the envelope, much of it will be hidden in the end, with the exception of the blockwork, none of the materials used are to be seen in the final building, instead acting purely as supports for the structure.
GROUND FLOOR
STRUCTURAL SYSTEMS ABOVE GROUND
FIRST FLOOR
PRIMARY
SECONDARY
BRACING
HORIZONTAL
250 Universal Beam running north/south with timber beam in-set to mount the joists onto.
FLOOR JOISTS: LVL 240 x 45 Hyspan joists doubled where necessary running east/west.
LVL blocking used between the joists to increase rigidity at 1800mm centers.
VERTICAL
BLOCKWORK WALLS: With reenforcement (see previous page), floor beams embedded to bear onto. STEEL: Square hollow sections used in front of the rumpus room to support living room projection.
As well as steel reenforcement in the blockwork, they are braced by their concrete filled cores.
HORIZONTAL
300 x 45 LVL Roof beams bearing on the timber stud walls’ top plate and/or steel sections.
200 x 45 Hyspan LVL Rafters running north/ south fixed into the roof beams.
LVL blocking between rafters at 1800mm centers and around skylight opening.
VERTICAL
TIMBER STUDS: 90x45 LVL studs. STEEL: Bedroom windows 89x89x3.5 Square Hollow Section
Nogging nailed between studs in 90x45 LVL
STEEL strips bracing in a X shape to withstand lateral forces. Plywood SHEET bracing also used.
Forces
The framing of the above ground supports is completed predominantly in timber members — this is in preference to steel as it is relatively cheap and lightweight for its load bearing capacity.
Framing for the highlight and skylight windows supports the window’s glass and frames after they are installed, they are the highest above ground load-bearing element in the structure.
Rafters are doubled are doubled around the perimeter of the skylight to carry the greater loads of the frame and glazing
LVL studs as primary support Nogging between studs as secondary Steel bracing in strips
300 x 45 Hyspan LVL Roof beam supports the 200 x 45 Hyspan Laminated Veneer Lumber (LVL) rafters with blocking between at 1800mm centers Blocking between rafters
300 x 45 Hyspan LVL roof beam
Primary Structural Elements
240 x 45 Hyspan Laminated Veneer Lumber (LVL) floor joists at 450mm centers with blocking between at 1800mm centers. Floor joists are doubled to increase their load bearing capacity instead of using steel sections Steel is used for the lintel above the garage door and in other places as specified by the engineer
EXAMPLE OF FORCES TRANSFERED THROUGH STRUCTURE
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250 Universal Beam
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INTERNAL NON-LOADBEARING PARTITIONS CONSTRUCTION ANALYSIS [ABPL20033] ASSIGNMENT 03
JEREMY BONWICK [697718] TUTORIAL 01 MIA WILLEMSEN
INTERNAL PARTITIONS
The internal partition walls have no structural impact on the building, they do not carry loads from the roof or floors above but instead work to define the spatial arrangement of the home. The scale of room is defined by the partitions, their intimacy and their flow. The kitchen and living area is left largely without partition to create an open-plan and spacious environment where as the partition of the corridor to the bedroom creates a narrowing and focusing towards that more private space. The placement of doors also creates a hierarchy in the home, with the en-suit for example only accessible from the walk-in-robe which is in turn only accessible from the bedroom. This is a flow of spaces where the en-suit is the most private and removed from the rest of the home as numerous thresholds in the form of partitions are placed between it and the front door. The partitions are lightweight in nature and do not need to be reinforced or braced to the same extent as the timber framed load-bearing walls as they only act to define the spaces.
Framing for the later addition of a vanity unit for the en-suit
WITHOUT OPENINGS
Typical stud walls are constructed with LVL 90x45 studs and nogging between with a top and bottom plate which do not carry any loads from the structure above.
WITH OPENINGS
The internal partitions with openings in them need to be supported with lintels — such as in the walls between the bedroom and the walk-in robe, where the opening for the door has an 90x45 MGP10 (machine graded pine rating 10) lintel installed. Pine is used for the lintels in the most part, as well as a few LVL and one horizontal 200 x 3 steel plate for the fireplace.
DOORS
Internal doors separate the spaces into rooms and create a barrier. The door between the bedroom and hallways connotes a public to private threshold with dimensions of 2400mm high and 970mm wide. This and many other doors in the house swing about an axis which is offset from the wall, unlike a traditional hinge. This gives a sense of grandeur as the door appears as part of the whole wall which can swing open.
FIXED FIRST FLOOR
Internally once the walls have been covered with plasterboard the non-load bearing and load bearing walls become hard to distinguish between, only the structure gives away the timber frame’s role, such as in the outer wall where the structure above its sitting on its top plate.
Doors as a gateway between spaces, thresholds that can be moved through. These doors are 32mm hollow core, pivot doors with a painted finish to match the walls
90x45 top plate Bottom plate
These internal partitions are freed from any load-bearing capacity and therefore are positioned by the architects agenda to create interior spaces for the inhabitants
PROGRESSION FROM PUBLIC THOROUGH TO PRIVATE
The internal partitions can also be used not to create rooms but for housing joinery
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Nogging 90x45 timber studs
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Doors define the boundaries to these volumes, closing or opening them changes the experience of the space greatly, making it either inviting or secluded
Partitions give the rooms dimension as well as volume, making them a 3d space, a cubic element to be occupied
MGP10 Pine Lintel over door opening
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ENVIRONMENTAL PROTECTIONS CONSTRUCTION ANALYSIS [ABPL20033] ASSIGNMENT 03
Box gutters are used throughout the roofing system to collect the rain water. The roof sheeting is laid with a minimum slope of 2° to prevent pooling and direct the water down to the gutters. The gutters feed into a sump which drains into the downpipes, taking the water either to one of the two 5000 liter rainwater tanks or to the storm water system.
The house is sealed from water entering via a number of techniques; the slab has a water proof tanking laid underneath and tied up into the wall system where there is another membrane to prevent water entering. Sarking is used in the roof structure to direct any water that has made it past the roof sheeting away from the internal spaces. Capping and flashing materials are used to seal the external skin from water entering.
WATER
GUTTERS
WATERPROOFING
HEAT
EAVES are used to protect from the summer sun in the bedroom, with the window set back enough that the winter sun is still permitted to enter to warm the space when it is cooler. INSULATION is also installed in the wall to prevent heat-loss. This works well to complement the active strategies (next page) for heating and cooling, reducing heat loss through the building envelope.
AIR
Air flow through the home can be used as a passive cooling strategy, there is a double hung window in the master bedroom which can be opened to permit air flow, cross ventilating with the sliding window on the west wall of the bathroom or through to the main living spaces if the windows there are also open. The prevailing winds come from the south and south-west in the summer when cooling is needed so the bedroom will draw air through and out.
SOUND
Insulation in the external walls of the house is mainly focused on the retention of heat, in the internal partitions though the insulation has the added effect of absorbing sound from room to room. The noise from the outside of the building is largely cut by the structure, its cladding and the insulation.
JEREMY BONWICK [697718] TUTORIAL 01 MIA WILLEMSEN
The environmental protections of the house providing comfort to the inhabitants by keeping the elements out — primarily preventing or mediating the way the home deals with water, heat, air and sound. The gutter system which is used to capture rainwater is hidden behind parapets, with only the downpipes visible from the outside. This is common amongst many of the environmental protections, being obscured or hidden away to not interrupt the facade. An exception is the eave over the bedroom window, a very visible element of the building’s heat-mediation as it defines the visual aesthetic of the cantilevered bedroom. Internally it also has an impact, with the space under the window appropriated to become joinery. The gutter over the garage also has visibility, changing the roof level with a bulkhead to contain it. This is perhaps acceptable to the architect as this space is not as public and on-display as other through the house where a greater effort has been made to keep the roof levels constant, or at least not dictated by the gutters or other roof systems. Openable sliding window for ventilation Box Gutter Downpipe
Rainwater head
ENVIRONMENTAL PROTECTIONS
The use of these passive strategies reduces the need for the building to use electricity to make the indoor environment more inhabitable by protecting it from the outdoors. The passive cooling and heating systems mean the home will use less electricity and the rainwater tank harvests the water from the roof to be used elsewhere on the property.
Parapets to conceal the roof system and give a seamless look to the facade
Summer: 17°
Roof slopes towards the box gutter Winter: 60°
Eave for shading of the northern sunlight
Insulation prevents heat-loss by holding the heat inside the building and sealing gaps between the structural members
Bulk insulation batts installed in the roof, floor and walls in the gaps between the primary, secondary and bracing elements
Gutter concealed by a bulkhead
Double glazed windows provide some protection from solar heat and noise transfer Horizontal bulk insulation in the floor cavity between joists and blocking
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Gutter system feeds into rainwater head and into the downpipe
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MECHANICAL AND ELECTRICAL SYSTEMS CONSTRUCTION ANALYSIS [ABPL20033] ASSIGNMENT 03
Potable water is supplied to the dwelling from the mains water supply, this supplemented with water from the two 5000 liter rainwater tanks on-site. The hot water boiler is fed with this and then distributed via insulated pipes to taps around the dwelling.
WATER SUPPLY
JEREMY BONWICK [697718] TUTORIAL 01 MIA WILLEMSEN
MECHANICAL AND ELECTRICAL SYSTEMS
The mechanical and electrical systems of the house are to bring services through to the house and pipe or cable to where they need to go. The most effective way of doing this to save money and reduce heat loss (in the case of hot water) is to reduce the piping distance by locating services near where they are needed and clumping together those rooms. The architect has placed the services such as the hot water boiler, hydronic boiler, solar power inverter and air conditioning unit on the west elevation and as such the west side of the house is where the majority of the bathrooms are placed, along with the laundry. In the below section, the en-suit bathroom backs onto a powder room which can share in the pipes, both basins being on the same wall, back-to-back. Electricity is fed throughout the house through the stud walls and ceiling, the switchboard is located in the garage on the eastern wall for ease of access and near a natural light source if the power fails.
HEATING
Hydronic heating is used to complement the passive strategies seen on the previous page. The hydronic boiler is separate from the potable hot water and feeds into pipes which run to the radiators throughout the house.
VENTILATION
The Air Handling Unit situated in the gallery hallway distributes the air into the space and expels air to the outside condenser unit. There are exhaust fans in the wet spaces which vent to the exterior and a range-hood over the stove in the kitchen.
COLLING
The house is cooled with an active system which requires, in addition to the two Air Handling Units in the gallery, a condenser on the exterior of the building. Melbourne is a predominantly heating climate so the AC will not regularly be in use.
HVAC
Electricity is distributed through wires around the home, running first from the mains to the switchboard then onto the GPO wall outlets, lighting and services such as the hot water system and garage door which require power sources to operate.
ELECTRICITY
The dwelling is installed with photovoltaic solar panels on the roof to generate electricity. This comes in the form of DC power which needs to be converted to AC for use in the home, the job of the Inverter which is located on the west elevation of the building.
SOLAR
The west facade has few windows to reduce heatload therefore artificial lighting is needed
Hot water service and hot water boiler
Water supply — hot and cold to the basin and shower in the en-suit
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Solar inverter and air conditioner
FI
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Hydronic boiler Hydronic floor radiator
Air handling unit
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FL
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Hydronic heated towel rail
GPO power outlet
Electric meter and switchboard
Fluorescent tube light fitting
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Waste pipes feed to the sewage system via gravity to the Sewer Access Point at the front, west corner of the site
Hot water boiler
HORIZONTAL
CONSTRUCTION ANALYSIS [ABPL20033] ASSIGNMENT 03
INTERNAL
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PHYSICAL ENCLOSURE SYSTEMS
JEREMY BONWICK [697718] TUTORIAL 01 MIA WILLEMSEN
Highlight and skylight windows bring light into rooms without needing windows to the west to reduce heat-load
PHYSICAL ENCLOSURES EXTERNAL
The final layer on the building is the physical enclosures, both internal and external. This system is a conscious choice to express or obscure parts of the building’s structural system — for example the blockwork is left exposed in its original state whereas the upper floor walls are clad in a zinc sheeting to create a more refined feel. There is a visual disconnect between the upper and lower floors, created through the contrasting materials — the black, vertically highlighted zinc against the light, horizontally accented blockwork — and the sense of overlapping created by the cantilever. Overall, the architect has sought to hide much of the structure in this building, opting to even try and obscure the roof sheeting for the most part to maintain the dark zinc aesthetic on the outer skin. Internally too the walls, floors and ceilings are clad in a variety of materials to leave a blank slate for the occupants. The window systems provide a primal feeling of comfort through surveying one’s surroundings, separating the internal from the external but still providing an aspect out (a primal sense which is heightened here due to the slope of the site).
FLOORBOARDS
180 x 19mm dimensioned timber floorboards laid in the living areas over 18mm particleboard to maintain a constant Finish Floor Level (FFL).
PLASTERBOARD
The internal walls are largely sheeted with plasterboard which is then painted for a smooth, largely untextured finish.
CARPET
Carpet is used as the final finish in the master bedroom and walk-in-robe, laid on the particle board to achieve the FFL.
TIMBER CLADDING
Outside the bedroom in the corridor a timber cladding is used on the walls to bring a sense of warmth to the entry.
TILES
Porcelain tiles are used in a large 600 x 300mm format in the gallery and other kid’s play areas as well as over a waterproof seal in the bathrooms.
TILES
In the bathrooms porcelain tiles are laid on the walls up to a height of 2.4 meters to match with the floor tiling.
CONCRETE
In either its rough state or polished, the concrete of the slab is used as a final finish in the basement area
SHEET CLADDING
The majority of the upper floor is clad in a zinc flat-lok material. The garage is clad with Lysaught ‘Mini-Orb‘ in a colourbond ‘cortex’ colour.
BLOCKWORK
The exterior visible blockwork is a Boral concrete block laid in a pattern specified by the architect.
ROOF SHEETING
Kip-lok roof sheeting has the benefits of no perforations for nails or screws thus performing better in terms of keeping the building envelope waterproofing
VERTICAL
The house’s roof is clad with Klip-Lok 406 roof sheeting which is fixed to battens to create the slope necessary for the drainage of water into the gutter system.
PARAPET CAPPING
The capping of the parapets wraps around to create a waterproof seal that overlaps the zinc cladding and is in a material that matches for consistency.
TIMBER CLADDING
Kiln Dried Hardwood (KDHW) cladding is used on the veranda outside the main living area as a wall cladding.
SKYLIGHT
The skylight permits light into the walk-in-robe. It is a fixed pane with a 15° fall to the south to drain water to the roof below.
WINDOWS
The window systems of the house are predominantly housed in Aluminum frames with KDHW reveals with double glazing installed.
Parapet capping to match with the zinc roof sheeting
Highlight window creates a pop-up in the roof which is quite strong architecturally, the changed roof height to achieve a larger amount of light entering the en-suit
Wall finishes creates the internal enclosure, including tiles in the bathroom and plasterboard in the bedroom and walk-in-robe Timber stud walls Plywood substrates and battens
Klip-lok roof sheeting concealed behind parapets
Flat-lok Zinc cladding Soffit lining with villaboard
Exposed blockwork expresses the materiality both internally and externally Exposed blockwork has a horizontal overtone due to the specified pattern which contrasts with the vertical strips of the Zinc cladding 0
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