Building a new home in Perth is one of the biggest financial decisions most West Australians will ever make and unlike buying an established property, there's no cooling-off period once you sign a WA building contract. That makes the conversations you have with your builder before you put pen to paper more important than almost anything else in the process.

Every year, homeowners across Perth and regional WA run into cost blowouts, disputed variations, and delayed builds that could have been avoided with the right questions asked upfront. Whether you're comparing volume builders in Perth's outer suburbs or a custom home builder for a knockdown-rebuild, these five questions will help you separate a reputable builder from one that could cost you thousands.

If you'd rather have an independent building consultant in Perth run these checks for you before you sign, that's exactly the kind of due diligence a good buyer's advocate or building consultancy service provides.

1. Are you registered with Building and Energy WA, and do you hold Home Indemnity Insurance?

This is the non-negotiable question. In Western Australia, it's illegal for a builder to take on residential work without a current licence issued by Building and Energy WA (part of the Department of Local Government, Industry Regulation and Safety) and registration with the Building Services Board. You can verify any builder's registration status yourself using the free online register before you commit to anything.

What to ask for:

• Their builder registration number (cross-check it on the Building and Energy WA register)

• A copy of their HII Certificate of Insurance, with the details verified against the insurer's public register (QBE, for example, publishes a Builders Warranty Insurance Certificate Register)

• Confirmation of public liability and workers' compensation cover

If a builder is reluctant to provide any of this, treat it as a red flag Building and Energy WA has prosecuted and fined registered builders in Perth for accepting payments without valid HII in place, so this isn't a formality you can afford to skip.

2. Is this a genuine fixed-price contract, and what exactly is included?

Ask your builder outright: "Is this a fixed-price (lump sum) contract, or are there items charged as Provisional Sums or Prime Cost (PC) items?"

A fixed-price contract means the quoted figure is what you pay, regardless of unforeseen site conditions or material price movements assuming no variations are requested. Provisional Sums and PC items, on the other hand, are estimates for work or fittings that haven't been finalised (site costs, tiling allowances, kitchen fit-outs), and the final bill can move up or down once the real cost is known. In a Perth market where soil conditions, retaining requirements, and trade availability vary suburb to suburb, these clauses are where budgets quietly blow out.

What to clarify:

• A full, itemised inclusions and exclusions list (fixtures, fittings, floor coverings, landscaping, driveways, fencing)

• How site costs are calculated, and whether a soil test and contour survey have already been factored in

• The process, paperwork, and margin (typically 15–20%) applied to any variations you request after signing

3. What is the progress payment schedule, and does it match the actual work completed?

Progress payments should be tied to stages of construction actually completed base, frame, lock-up, fixing, and completion not to arbitrary dates or the builder's cash flow needs. Ask your builder to walk you through exactly what triggers each payment claim, and how that lines up with what your bank or lender will require before releasing funds.

Questions worth asking:

• What are the fixed start and completion dates in the contract, and what happens if the build runs over?

• Who inspects each stage before a progress payment is released do you get the option to have an independent building inspector check the work first?

• How are delays caused by weather, material shortages, or trade availability handled under the contract?

Getting clarity here protects your cash flow and gives you leverage if the build timeline starts to slip which is common in WA's current construction environment given ongoing trade and material supply pressures.

4. Can I see completed homes, speak to past clients, and confirm how long you've built in WA?

Marketing photos and display homes only tell part of the story. Ask to see homes the builder has completed in the last 12–24 months ideally in a similar price bracket and style to what you're planning and request contact details for at least two or three recent clients you can call directly.

Dig into:

• How many homes has this builder completed specifically in Western Australia (not interstate)?

• Are they currently involved in any disputes before the State Administrative Tribunal (SAT) or Building and Energy WA?

• Who is the dedicated site supervisor for your build, and how often will they be on site?

• What warranty periods apply to structural work versus non-structural finishes, separate from the six-year HII cover?

A builder with a strong local track record in Perth's soil types, council requirements, and weather conditions is generally a safer bet than one new to the WA market.

5. What happens if we disagree, and how are variations and defects handled after handover?

Even well-run builds hit friction points. Before you sign, ask your builder to explain their dispute resolution process in plain terms not just what's written in the contract's fine print.

Ask directly:

• If we disagree about a variation cost or a defect, what's the step-by-step process to resolve it?

• What's your defect liability period, and how do I lodge a maintenance request after we move in?

• Do you use subcontractors, and if so, who is ultimately responsible if their work is defective?

• Is there a single point of contact for questions and concerns throughout the build, from contract signing to handover?

Because Western Australia offers no cooling-off period on building contracts, this is your last real opportunity to negotiate terms, request changes in writing, or walk away once signed, you're locked in.

Final Advice:

Asking these five questions won't guarantee a perfect build, but it will filter out unregistered, underinsured, or poorly organised builders before they get anywhere near your deposit. Read every page of your contract, get anything you're unsure about checked independently, and remember: a reputable Perth builder will welcome these questions, not avoid them.

If you'd like a second set of eyes on a contract before you sign checking registration, HII, inclusions, and fine print against WA regulations an independent building consultant can review it with you and flag anything that needs negotiating before it's too late to change.