In recent decades, concrete slab foundations have become the norm for new homes. Homes built on a concrete slab foundation generally achieve higher energy ratings because of the insulation provided by the concrete. In contrast, homes built on stumps require careful attention to insulation of the subfloor in order to achieve a satisfactory energy rating. With ever increasing regulatory requirements around minimum standards for energy ratings, homes built on stumps are now less common.
In addition, homes built on a concrete slab foundation usually cost less than the equivalent home built on stumps. This is because constructing the stumps and sub floor framing is very labour intensive, stump foundations mean more insulation is needed and the extra heigh stumps require more cladding materials around the perimeter of the home.
Homes built on a concrete slab foundation are generally considered to be more solid and less susceptible to movement within the building – we’ve all been in old homes where the floor feels springy or uneven because the stumps have rotted or inadequate stump footings were provided. Re-stumping a home to remedy this is expensive, but building on a concrete slab foundation avoids these issues.
Stumps still have a place as a foundation option, commonly for homes where the floor level is raised above natural ground level – this may be to capitalise on views or to meet a minimum flood level requirement. In this situation, it may be more cost and labour effective to build on stumps rather than fill the site to raise the slab level.