NSW rules for underpinning and restumping

When approval is needed

NSW planning law sorts small residential projects into exempt development (no approval), complying development (fast-track certificate) and development needing a full council DA. Genuine like-for-like maintenance and minor repairs generally sit in the exempt category. Underpinning is a harder case: because it alters the structural support of the building, it typically cannot be waved through as simple maintenance, and most jobs proceed with approval, either through a council development application or, where the work qualifies, a complying development certificate issued by council or a registered private certifier. The boundaries depend on your property, the zoning and whether heritage controls apply, so the honest advice is to check with your council or a private certifier before work starts rather than rely on a contractor's assurance that "no one bothers with approval for this". Our regulations hub compares each state's approach.

Contractor licensing

Residential building work in NSW worth more than $5,000 (labour and materials) must be done by the holder of a contractor licence, regulated by Building Commission NSW alongside NSW Fair Trading. Since most underpinning jobs land between $10,000 and $40,000, every quote you receive should come from a licensed contractor, and the licence number should appear on the quote and the contract. Contract rules scale with value: work over $5,000 needs a written contract with prescribed terms, and work over $20,000 needs a full home building contract with a progress payment schedule. A contractor who wants a big job done on a handshake is exposing you, not saving you paperwork. Licensed work also carries statutory warranties under the Home Building Act, including that the work will be done with due care and skill and comply with the plans, which is a legal backstop you simply do not have with an unlicensed operator.

Home Building Compensation cover

Where the contract price is more than $20,000 including labour and materials, the contractor must take out Home Building Compensation (HBC) cover, run through the state insurer icare, before taking your deposit or starting work. HBC protects you if the builder dies, disappears or becomes insolvent and cannot finish or fix the job. You should be given a certificate of cover naming your property; keep it with the contract. A significant share of underpinning quotes cross the $20,000 line, so ask about HBC at quote stage.

Engineering sign-off

Underpinning in NSW is engineer-led by convention as much as by regulation. A structural or geotechnical engineer should diagnose the movement, design the fix and, ideally, inspect at key stages, with an engineer's report typically costing $600–$1,200 and design work up to $2,500. Where the job goes through an approval pathway, the certifier will expect engineering documentation, and your insurer may ask for it too if the damage becomes a claim. Before committing to any method, it is worth confirming whether you need underpinning at all: plenty of cracked NSW homes are moving seasonally rather than failing, and our underpinning guide explains the difference.

Checking a licence

You can verify any NSW contractor licence free online through the NSW Government's licence check (via Service NSW). Confirm the name on the licence matches the entity on your contract exactly, the licence class covers the work, the licence is current, and check for any published disciplinary history. It takes five minutes and filters out most problems before they start. Keep everything at the end of the job: the contract, any approval or certificate, the engineering documents and the HBC certificate. Buyers' conveyancers ask about structural work, and a tidy paper trail protects your sale price as much as the underpinning protects the house. If you are still collecting quotes, our Sydney directory lists underpinning specialists, and comparing three itemised quotes remains the single best consumer protection available.