Concrete slab integrated footings – These require substantial excavation on all but level sites, increasing impact. They can reduce construction costs where the slope is low. They can be an effective part of passive design where the climate allows for earth coupling.
Waffle pod slabs – These can be a cost-effective solution on flat sites and they don’t require major excavation. Waffle pods reduce the overall cost of the slab because they create a ‘void’, which uses less concrete and reduces the cost of labour. This means they also reduce wastage and have lower embodied energy than a typical concrete slab.
Detached strip footings – These, combined with loadbearing brickwork to floor level, can reduce excavation.
Engineered steel pile systems – These can support masonry walls, reduce excavation and site impact, and make for faster construction. Cost varies with application but these systems are generally more expensive than strip footings.
Floor systems High-mass floors High-mass floor system options include:
Concrete slab-on-ground – This is the most common high-mass floor system. In cold climates, insulating under the slab will reduce heat loss to the ground; in permanently hot climates, insulating under the slab will prevent heat entering the home. If the slab is not insulated, the summer cooling benefit of earth coupling may or may not exceed the additional energy required in winter to compensate for the uninsulated slab on ground. Earth-coupled (uninsulated) slabs are effective where deep (>3m) earth temperatures remain constantly between 16°C and 19°C.
Suspended slabs or precast concrete beams – These can be used with lightweight infill and concrete topping. To contribute positively to thermal performance, the underside of suspended floors, including subfloor spaces, must be insulated if externally exposed.
Lightweight suspended concrete floor systems – (such as autoclaved aerated concrete (AAC) floor panels, or thin poured concrete slabs on permanent formwork, supported on floor joists). These may be competitive in cost with conventional timber- and steel-framed floors, and can reduce site impacts where a slab floor is preferable to a lightweight floor. The underside of thin concrete slabs must be insulated; AAC provides sufficient insulation on its own in many climate zones.
