Frequently asked questions

Read three things: width, direction and behaviour. Cracks under about 5 mm are usually cosmetic; diagonal cracks from window and door corners, stepped cracks in brickwork, and any crack that keeps growing point to footing movement worth a structural engineer's opinion. A single crack rarely proves a problem, so it is the combination and the ongoing growth that matter.

Concrete cancer is the common name for concrete spalling caused by the steel reinforcement inside concrete corroding. Rust takes up several times the volume of the steel it forms from, so as the reinforcement rusts it expands and cracks the concrete apart from the inside. It shows up as rust stains, bubbling or drummy render and concrete flaking away, most often on balconies, basements and coastal buildings.

As a 2025 guide, a residential underpinning job commonly runs from roughly $4,000 to $15,000, with the full spread across jobs from about $3,000 to $25,000, and major piling jobs reaching $40,000 to $80,000 or more. It is quote-driven work, so the real figure depends on the method, soil, depth to stable ground, access and extent. See our cost guide for the detail.

Source: Underpinning and concrete repair cost guide.

Often not. Standard Australian policies commonly exclude gradual movement from reactive clay, trees, settlement or poor construction, but may cover sudden damage from an insured event such as a pipe that suddenly bursts. It depends entirely on your policy and the cause, so read your Product Disclosure Statement and get a structural engineer's report on the cause before assuming either way.

Source: Is subsidence and concrete cancer covered by insurance?

A structural engineer first. The engineer independently diagnoses whether the footing has moved and why, and specifies any repair. A remedial or underpinning contractor then prices and carries out that repair. Getting the engineer's report first means every contractor quotes on the same diagnosis, so you can compare them fairly and avoid paying for work you may not need.

Remedial Building Help is an independent information resource, not a builder or contractor. Our guides are free to read. If you want quotes, you can send an enquiry and we will match you with a remedial or underpinning contractor serving your area at no cost and with no obligation. We never publish or sell your details, and we always recommend confirming a contractor's licence and insurance directly.