Underpinning & restumping firms in Perth

Foundation repair in Perth

Coastal sands fail differently from eastern-states clay: washouts from leaking services are a leading cause, and fixing the leak comes before any underpinning. Inland clay pockets behave like Adelaide in miniature. The subsidence signs guide applies either way.

Restumping or underpinning: which one do you need in Perth?

The symptom tells you which trade to call. Sloping or bouncy floors, doors and windows sticking, and gaps opening between floor and skirting point to failed stumps under a timber-framed house: that is restumping (reblocking in Victoria). Stepped cracks in brickwork, cracks that widen with the seasons, and a slab home pulling away from its footings point to footing movement: that is underpinning. Our guides on the signs of failed stumps and the signs of subsidence walk through each, and restumping vs reblocking vs underpinning settles the terminology.

In Perth, it is nearly always underpinning: Double brick on slab over coastal sand: trouble usually shows as stepped brick cracks, and the cause is often a leaking pipe washing out the sand rather than clay movement. Get an engineer's assessment first and give every contractor the same report to price against. See engineers' reports and the methods compared.

Permits, licences and insurance in WA

Building permits under the Building Act 2011. WA runs building approval under the Building Act 2011, with permits issued by your local government's permit authority. Applications come in two flavours: a certified application (BA1), where a private building surveyor has already checked compliance and the council has up to 10 business days to issue the permit, and an uncertified application (BA2) for smaller residential work, where the council does the checking and has up to 25 business days. Work that affects the structure of a house, and underpinning plainly does, generally needs a permit, while genuine like-for-like maintenance may not. The exemptions are specific and councils apply them case by case, so check with your local government or a private building surveyor before assuming your job is exempt. Most underpinning contractors arrange the permit; get the permit number before work starts, and keep the permit with the engineering documents when the job wraps up, because unauthorised structural work is expensive to regularise later and awkward at sale time. Our regulations hub compares WA with the other states.

Registered builder requirements. Building work in WA valued over $20,000 must be carried out by a registered building contractor. Registration sits with the Building Services Board, administered by Building and Energy, the state building regulator within WA's industry regulation department (see commerce.wa.gov.au). Since most underpinning jobs cost $10,000-$40,000, many WA foundation repairs cross the registration threshold, and any full restumping job at $15,000-$30,000 certainly does. Below $20,000 registration is not mandatory, which is exactly where you should be more careful, not less: an unregistered operator quoting $18,000 has fewer obligations and you have fewer remedies.

Home indemnity insurance. For residential building work over $20,000, the builder must take out home indemnity insurance in your name before accepting any money or starting on site. It protects you against losing your deposit or being left with incomplete or defective work if the builder dies, disappears or becomes insolvent. Ask for the certificate at contract stage and keep it with the permit paperwork, because the cover follows the property and matters to future buyers as well as to you. A builder who hedges on home indemnity insurance for a $30,000 job is not someone to hand a deposit to.

Engineering and owner-builders. Perth's sands are kinder to footings than eastern-states clay, but WA still has reactive pockets, fill sites and coastal limestone quirks, and underpinning should always be designed by a structural engineer rather than sized by a salesperson. Expect an engineer's report at $600-$1,200 and a soil test at $400-$1,000; permit authorities expect engineering documentation for structural work. Owner-builders get a brief mention because WA formalises them: to do your own building work over $20,000 you need owner-builder approval from the Building Services Board, and restrictions apply, including limits on selling the property within seven years unless you take out home indemnity insurance. For structural foundation work, owner-building rarely makes sense; our underpinning guide explains why this is specialist territory.

Full detail, including the checklist: the WA rules explained.

What it costs in Perth

Perth quotes are underpinning and resin-injection quotes: $10,000 to $40,000 typical. Fixing the leak that caused the washout comes first, and it should be on the quote.

Full breakdowns: restumping costs, underpinning costs, when a partial restump is enough.

Getting quotes you can compare

A quote you can compare states the method, the extent (number of stumps, or metres, piles or zones for underpinning), the stump material, size and founding depth or the depth to bearing, who obtains the permit and whether its cost is included, the insurance that applies, what happens to cracks afterwards, and the warranty in writing. A number produced in the driveway without a look under the floor or an engineer's report is a guess, and the cheapest guess is the one that costs you later.

• Which licence or registration do you hold, and can I check it on the register?
• Is the permit your responsibility, and is it in this price?
• What stump material, size and founding depth are you quoting, and why?
• Have you priced against the engineer's report, or your own diagnosis?
• What is the warranty, and what insurance sits behind it if you close down?
• How many days on site, and will the house be habitable throughout?

More in choosing a contractor and what the process looks like.