Building or renovating in WA: what you should know

In WA, building work valued at $20,000 or more that needs a building permit can only be carried out by a registered building contractor. Registration is how the Building Services Board checks that builders have appropriate qualifications and experience.

Ask any builder for their registration number, then check it on the Building and Energy register. Only registered builders can take out home indemnity insurance, which is the next thing to check.

For residential building work over $20,000, the builder must take out home indemnity insurance in your name. They must give you the certificate before accepting any payment, including a deposit, and before starting work.

It protects you if the builder dies, disappears or becomes insolvent and can't finish the work or fix faulty work. In most cases the policy covers construction and six years from practical completion.

Associated work on its own, such as a pool, carport, pergola or landscaping under a separate contract, doesn't require this insurance.

The Home Building Contracts Act 1991 applies to fixed-price home building contracts valued between $7,500 and $500,000. Under those contracts, the deposit can't be more than 6.5% of the contract price.

After work starts, each progress payment can only be for work actually done or materials already supplied. Over $500,000 the deposit limit doesn't apply, but insurance cover for a lost deposit is still capped at $40,000, so the size of any deposit matters.

A variation is any change to the work in your contract, whether you ask for it or the builder finds it's needed. It must be in writing, dated and signed by both of you before the varied work begins, and should state the effect on price and time.

• Development approval from your council checks the design against the local planning scheme and the Residential Design Codes: setbacks, height, overshadowing, privacy and streetscape. Some compliant projects don't need it.
• A building permit checks the design against building standards and is required before construction starts on most building work. For residential work over $20,000, the insurance certificate forms part of the application.

WA adopted the National Construction Code 2022 energy efficiency requirements from 1 May 2025. New homes must now achieve a minimum 7-star NatHERS rating and meet a whole-of-home energy budget, along with updated condensation management provisions.

An energy assessor rates your design before the building permit is lodged. Orientation, glazing, shading and insulation choices made at design stage have the biggest effect on the result.

Under the Home Building Contracts Act, your builder must fix defects at no cost if you notify them in writing within four months of practical completion. Keep a list as you settle in, and send it in one written notice.

Separately, complaints about the standard of workmanship can be lodged with Building and Energy within six years of the work being completed.