WA Building Contracts: What to Check Before You Sign

Western Australia's Home Building Contracts Act 1991 sets clear rules for home building contracts — deposit caps, cooling-off rights, price variation limits, and required contract contents. MBA contracts are particularly common in WA.

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What WA law requires

Written contract

Home building work of $7,500 or more must be in a written home building work contract.

Deposit cap

• Contracts $20,000 or more: maximum deposit 5% of contract sum
• Contracts under $20,000: maximum deposit 10%

Cooling-off period

For contracts $20,000 or more: 5 clear business days after signing to rescind. Builder must not commence work during this period.

Required contract contents

Must include:

• Names and addresses of parties
• Description of the work, with plans and specifications
• Contract price and payment schedule
• Date for commencement and completion
• Provisional sums and prime cost items (with estimates)
• Variation procedure
• Dispute resolution process

Price variation protections

Price increases after signing are limited to defined circumstances — not open-ended escalation. Variations, provisional sum adjustments, and specific contractual events.

Home indemnity insurance

Required for residential building work above certain thresholds. Certificate must be provided before deposit.

Statutory warranties

6 years from practical completion for all construction defects (structural and non-structural).

Clauses to watch in your WA contract

Notice of Proposed Complaint — If a dispute arises later, WA requires a written Notice of Proposed Complaint at least 14 days before lodging with the Building Commissioner. Good practice from day one: put everything in writing.

Extensions of time — Track and dispute in writing.

Provisional sums — Check allowances are realistic.

Progress payments — Align payments with completed stages, not dates.

Before you sign — WA checklist

• Written home building work contract (if ≥ $7,500)
• Deposit ≤ 5% (if contract ≥ $20,000)
• Home indemnity insurance certificate before deposit
• Cooling-off period — use for legal review
• Price variation clauses understood
• All plans and specifications attached

Can you negotiate your building contract? →

If things go wrong in WA

• Building disputes in WA →
• Building disputes in Australia →

Keep the record from signing day

Chronicle Build tracks every decision and variation against your WA contract — so if you ever need Building and Energy or SAT, your evidence is already organised.

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Frequently asked questions

What is the maximum deposit in Western Australia?

Under the Home Building Contracts Act 1991, the maximum deposit is 5% of the contract sum for home building work contracts of $20,000 or more. For contracts under $20,000, the maximum is 10%.

Do I have a cooling-off period in WA?

Yes. For home building contracts of $20,000 or more, you have 5 clear business days after signing to rescind. The builder must not start work during this period.

Can my builder increase the price after signing in WA?

The Home Building Contracts Act limits price increases to specific circumstances — variations agreed in writing, provisional sum adjustments, and defined events. Open-ended price escalation clauses should be flagged with a lawyer.

What insurance is required in WA?

Home indemnity insurance is required for residential building work above certain thresholds. The builder must provide a certificate before you pay a deposit.