The Construction Process
CONSTRUCTION PROCESS
All structural design should be prepared by a competent person and may require preparation or checking by a qualified engineer. Qualified professionals, architects and designers provide years of experience and access to intellectual property that has the potential to save house builders time and money as well as help ensure environmental performance. All construction has to comply with the Building Codes.
SOME COMMON SYSTEMS
LIGHTWEIGHT WALLS WITH HEAVYWEIGHT FLOOR
- Insulated lightweight wall construction on an exposed concrete slab (not covered with insulating materials like carpets) is an efficient and economic combination on level sites in most climates. It is also the most commonly used in most states.
- Concrete slabs provide thermal mass to even out diurnal temperature ranges, reducing heating and cooling energy and increasing comfort.
- Embodied energy of normal reinforced concrete is high but can be reduced by using recycled steel and aggregate. Cement from an efficient kiln and use of cement extenders can further reduce embodied energy.
- Brick veneer is an inefficient, high embodied energy cladding system. The brick has no structural role.
FOOTING SYSTEMS:
- Slab integrated footings require excavation on all but level sites, increasing impact. They can reduce construction costs where slope is low.
- Detached strip footings with load bearing brickwork to slab level can reduce excavation but increase embodied energy content
- Strip footings and piers add embodied energy and create site disturbance. They are not easily relocated or re-used. Cost is low.
- Engineered steel pile systems capable of supporting masonry walls are now available. They reduce excavation and site impact and speed construction. Cost varies with application but is generally more expensive than strip footings.
- Bore in or pile type systems have minimal site impact, can be relocated and re-used and have lowest embodied energy. Cost: medium to high.
- Pole frame construction integrates footing and framing, giving benefits on steep sites with high wind exposure. Embodied energy is low for timber and medium for concrete or steel poles. Durability and efficient use of structure are important to maximise efficiency and reduce cost. Cost: medium to high.
LIGHTWEIGHT FLOOR WITH HEAVYWEIGHT WALLS
- A lightweight insulated floor can reduce site impact and construction costs on sloping sites. Reverse brick/concrete block veneer clad with insulated lightweight cladding (fibre cement or plywood) or internal masonry walls, provide thermal mass for effective passive design.
- Embodied energy in the masonry will be offset by operational energy savings during the life span of the building in most climates, providing good insulation levels are included.
- Timber framed flooring: has low embodied energy, low thermal mass but requires additional insulation in most climates. It is suitable for flat or sloping sites and durability is good when termite protection and sub-floor ventilation are correctly installed. Sustainably sourced timbers should be specified or biodiversity impact will be high. These floors can be a source of air infiltration if not well sealed. Low cost.
- Steel framed flooring: as for timber framed but with slight increase in embodied energy. Durability is high. They can have greater durability advantages in termite prone areas and often have lower transport costs than equivalent timber structures. Usually more expensive than timber.
- Steel frame conducts cold so in northern climates may not be the best choice for residential use.
- Lightweight suspended concrete floor systems are now available that are competitive in cost with timber and steel framed floors.