Underpinning and restumping in Adelaide and South Australia

Foundation repair in South Australia

Adelaide's black earth and red-brown clays swell and shrink dramatically between wet winters and dry summers, which is why crack-watching is a local pastime. Slab and double-brick homes dominate, making underpinning the usual conversation - though stumped villas and cottages still turn up. Read the movement signs before anyone quotes you.

Why subsidence is so common in Adelaide

Much of the Adelaide Plains and the foothills sit on heavy clay that takes on water through winter and dries out hard through summer. Footings that were sound for decades can drop at one corner when something changes the moisture in the soil beneath them: a long dry spell, a large tree growing close to the house, or a leaking stormwater or sewer pipe softening one side. The result is the familiar Adelaide pattern of stepped cracks in brickwork, doors and windows binding on one side of the house, and gaps opening between the floor and the skirtings. It is not confined to any one suburb, and it shows up in regional centres on similar soils too.

Underpinning or restumping: which does your Adelaide house need?

Go by what the house stands on, not by the word a tradesperson used. Most Adelaide homes are double brick or brick veneer on strip footings, or newer homes on a concrete slab. When those footings settle, the fix is underpinning: new support under the footing by mass concrete, screw piles or resin injection, designed by an engineer and priced per metre or per pile. Older villas, bungalows and cottages with timber floors over a crawl space stand on stumps, and sinking or rotten stumps are fixed by restumping, which some people in SA call reblocking or re-levelling; it is the same job, priced per stump. Some houses have both, a stumped original with a slab extension, and movement at the join between old and new is the usual tell. The three terms compared.

Monitor first, then get an engineer's report

Because underpinning is expensive and some Adelaide cracking is seasonal, the sensible first step is often monitoring rather than digging. Photograph and date the cracks, measure the widest points, and watch whether they keep growing across a season or close up again. If they keep growing, an independent structural engineer's report tells you what is actually moving and which method is justified, before a contractor with a product to sell gets involved. Ask any firm whether their design is engineer-specified and whether the work comes with a written warranty. Engineer's reports explained, what underpinning costs, and the SA approvals and licensing guide.