Western Australia’s consumer protection framework has one feature that should shape how every Perth homeowner approaches the builder decision: Home Indemnity Insurance is mandatory for residential building work valued over $20,000, and the builder must provide you with the certificate before commencing work or taking a deposit.
That is a legal obligation on the builder and a hard verification point for you. A builder who cannot produce the certificate cannot lawfully take your money — and inability to obtain the cover says something important about their financial position, because insurers assess builders before issuing it.
Verify Registration and Insurance First
Builder registration
Residential building work above the threshold in WA must be carried out by a registered building contractor. Registration is administered by the state regulator and can be verified through the public register.
Confirm:
- The registration is current, not expired, suspended or cancelled
- The class covers the work
- The name on the registration matches the entity that will sign your contract. A registered individual operating through an unregistered company, or a company whose registration depends on a nominated supervisor who has since left, is a serious risk.
- Any disciplinary history recorded against the registration
Also run a company search on the contracting entity — how long it has traded, who the directors are, and whether those directors have previously been involved in companies that were wound up.
Home Indemnity Insurance
Mandatory for residential building work valued over $20,000. Key points:
- The builder takes it out, and must give you the certificate before commencing work or taking a deposit
- It covers financial loss where the builder cannot complete the work or rectify defects due to death, disappearance or insolvency
- Limits of up to $200,000 for completion and defect rectification, with deposit protection up to $40,000
- A $500 excess applies to claims
- The period is six years from practical completion, and it transfers to subsequent owners within that period
- Owner-builders are generally exempt, unless they sell within seven years of obtaining the building permit
Verify the certificate independently rather than accepting a PDF at face value. It should name your property, the contract value and the scope of works.
Where to Find Candidates
In rough order of reliability:
- A recommendation from someone whose completed project you have walked through. Not a friend of a friend — someone who lived through it and will tell you what went wrong.
- Your building designer’s or architect’s list. Designers work with builders repeatedly and know who prices honestly and who finishes.
- Master Builders WA and HIA member directories. Not a quality guarantee, but an indicator of a business operating formally.
- Local project signage. Builders working in your suburb on similar housing understand the specific issues — the double brick, the sand, the salt.
- Trade referrals. A good bricklayer, plumber or electrician knows which builders pay on time and run organised sites.
Be cautious with lead-generation platforms, which connect you with builders who paid for the lead rather than those who do the best work.
Perth-Specific Experience Matters
This city’s construction demands particular knowledge, and a builder who works mostly on new framed homes in the growth corridors will struggle with a 1970s double-brick renovation.
For more detail on this part of the project, see Renovating a 1970s Double Brick Home in Perth: A Practical Guide.
Ask specifically about:
- Load-bearing masonry wall removal. How many have they done? Who is their structural engineer? What does the propping and needling sequence look like? What is their allowance for making good?
- Slab cutting. If wet areas or the kitchen sink move, what is their rate for saw-cutting or core drilling the slab and reinstating with correct falls?
- Chasing brick for services. How do they route electrical and plumbing in solid masonry, and what does the making good involve?
- Brick matching. Where an opening is enlarged, how do they handle the transition — secondhand bricks or rendering?
- Cavity insulation. Do they retrofit it, and do they borescope the cavity first?
- Salt damp and wall ties. Have they dealt with either, and how?
- Coastal specification. Do they specify 316 stainless fixings and marine-grade finishes as a matter of course near the coast?
- The R-Codes. Do they understand which deemed-to-comply provisions your design has to satisfy, and can they design to avoid a planning application?
A builder who answers these confidently has worked on Perth’s real housing stock. One who has not considered them is telling you something.
A related guide to consider while planning this work is Do You Need Council Approval to Renovate in Perth? The 2026 Rules Explained.
The Site Visit That Tells You Most
Ask each shortlisted builder to walk the property before quoting, and watch what they do.
A builder who works properly in Perth will tap and assess the internal walls to determine which are load-bearing, look at the ceiling to work out how the roof loads are carried, check the base of external walls for salt damp, look at the wall for horizontal cracking that suggests tie corrosion, check whether the weep holes are clear, note the ground levels against the brickwork, look at the roof and the eaves, and ask where the existing plumbing runs.
A builder who walks through, takes some measurements and leaves has priced the visible work and assumed the rest. In double brick, those assumptions become expensive variations.
The Reference Check That Works
Every builder supplies three references who will say good things. Ask instead for the contact details of the last three projects completed, and ask those owners:
- What was the contract sum, and what was the final invoice? The gap is the most informative number you will get.
- How many variations were there, and were they priced before the work or after?
- Did the project finish on the contracted date, and if not, why?
- How did the builder handle the structural work — was the engineering resolved before demolition?
- How much dust and disruption did the masonry work generate, and how was it managed?
- Were the site kept clean and the neighbours managed?
- How was the defects period handled?
- Would you use them again — and, the key follow-up, what would you do differently?
Ask to visit a current site as well as a completed one. A live masonry renovation site tells you a great deal about how a builder manages dust, waste and sequencing.
Getting Comparable Quotes
Tender on identical documents. Every builder prices the same drawings, structural engineering, specification, finishes schedule and inclusions list. On a masonry renovation, the structural documentation matters especially — without it, each builder makes different assumptions about beam sizes and bearing, and the quotes are not comparable.
Require an itemised breakdown — trade-by-trade allocations, preliminaries, margin and any provisional sums.
Interrogate provisional sums. A builder can win a tender by setting them low and adjusting upward once you are committed.
Check the exclusions. Common ones that become expensive in Perth: structural steel and engineering, slab cutting, making good after chasing, asbestos removal, limestone retaining, salt damp remediation, brick matching or rendering, service upgrades, landscaping, driveways, and building surveyor and permit fees.
Be suspicious of the outlier. If three quotes land at $240,000, $255,000 and $175,000, the low quote has misread the structural scope or intends to recover through variations. Ask them to walk you through their figure.
Understanding the Margin
A builder’s quote has three components: direct trade and material costs; preliminaries covering site establishment, scaffolding, waste removal, supervision and insurances; and margin, the gross profit before overheads.
- Preliminaries typically run 8 to 15 per cent of a Perth residential project, and higher on constrained sites or where masonry demolition generates significant waste handling
- Margin typically runs 12 to 20 per cent for mainstream work, 18 to 30 per cent at the premium end
A builder quoting materially below these ranges is underestimating, intending to recover through variations, or running so thin that a single problem project puts them under. The productive negotiation is about scope and specification, not margin.
The Contract
Use a standard form — Master Builders WA or HIA residential contracts — rather than a builder’s own document. Provisions to read carefully:
- The contract price and what it includes. Cross-reference against the quote, the structural documentation and the specification.
- The progress payment schedule. Payments tied to completed stages, not dates. Deposit amounts are regulated.
- The variation clause. Variations must be in writing, priced and signed before work proceeds. This single clause prevents most disputes.
- Completion date and extension of time provisions.
- Latent conditions. Specifically, what happens if salt damp, corroded wall ties, asbestos or failed under-slab plumbing is discovered. A good Perth contract addresses this in advance.
- Liquidated damages for late completion, if any.
- The defects liability period.
- Dispute resolution and the process before escalation.
Warning Signs
- Pressure to decide quickly, particularly a discount that expires
- A request for a deposit before providing the Home Indemnity Insurance certificate — this is not merely poor practice, it is unlawful on work over $20,000
- Reluctance to provide a registration number
- A single-page quote for a six-figure project
- No structural engineering for a project involving masonry wall removal
- No written contract, or a suggestion that one is unnecessary
- Cash discounts, which remove your consumer protections
- The person quoting is not the person building
- Vagueness about subcontractors, particularly the bricklayer and the waterproofer
- Unwillingness to let you speak to past clients directly
- A pattern of blaming previous clients
Managing the Job
- Make decisions early and stick to them. Owner indecision is the largest single cause of delay.
- Order long-lead items before construction, allowing extra for eastern-state freight.
- Hold a weekly site meeting with a short written record.
- Approve variations in writing before the work happens.
- Photograph everything before it is covered — waterproofing, structural steel and bearing points, service runs, cavity insulation, termite management.
- Do not pay ahead of the schedule. Paying early to help a builder’s cash flow is how homeowners become unsecured creditors.
- Attend or obtain records of the building surveyor’s inspections.
- Manage the dust expectation. Masonry demolition generates far more dust than timber work. Agree the containment approach in writing before it starts.
If Things Go Wrong
Raise the issue with the builder in writing, describing the defect and the resolution sought. If that fails, WA’s building services regulator handles complaints about registered builders and can issue building remedy orders requiring defective work to be rectified.
The State Administrative Tribunal hears building disputes. Where the builder has died, disappeared or become insolvent, the Home Indemnity Insurance policy is the claim path — which is why obtaining and verifying that certificate before paying anything matters more than any other check in this guide.
What Good Looks Like
A good Perth renovation builder holds current registration in the correct name, provides the Home Indemnity Insurance certificate before taking a deposit without being asked twice, quotes from complete documentation including structural engineering, prices provisional sums realistically, uses a standard form contract, and issues written variations before doing work. They understand double brick, slab cutting and the R-Codes. They have subcontractors who have worked with them for years, and past clients who describe the process as unremarkable.
That last quality is underrated. The best outcome is not a dramatic story — it is a project that finished roughly when it was meant to, cost roughly what it was meant to, and left you with a builder you would call again.
For cost benchmarks, see our Perth renovation cost guide, and for the approval framework, our guide to Perth approvals.
Sole Traders, Small Builders and Volume Operators
Perth’s residential market has distinct contractor types.
- The trade-based sole operator — often a carpenter or bricklayer running small jobs with regular subcontractors. Good value on bathrooms, kitchens and patios. Limited capacity for structural work or permit coordination.
- The small to mid-sized renovation builder — three to eight projects with a supervisor on each. The right choice for extensions and whole-house renovations involving structural change. This is where most Perth renovation work sits.
- The patio and alfresco specialist — a distinct Perth category given how central the alfresco is to local housing. Efficient and competitively priced for a standalone structure, but not a renovation builder.
- The volume or project builder — Perth’s volume building industry is among the largest and most competitive in the country, which makes it excellent value for a knockdown rebuild and poorly suited to renovation where nothing is standard.
Matching the type to the project matters more than finding “the best builder”. A patio specialist will struggle with a load-bearing wall removal, and a volume builder will price a $60,000 renovation uneconomically.
Questions Worth Asking at the First Meeting
- How many projects are you running, and who supervises mine day to day?
- Which of my internal walls are load-bearing, and what would each opening cost?
- Who is your structural engineer, and at what stage do you engage them?
- What is your rate for slab cutting if the plumbing moves?
- How do you handle chasing services into masonry, and what does making good involve?
- Are your key trades — bricklayer, plumber, electrician, waterproofer — regulars or engaged per job?
- How do you manage brick and mortar dust if we stay in the house?
- Will you use the certified or uncertified permit route, and why?
- What happens if we find salt damp or corroded wall ties?
- Which parts of my project concern you most?
That last question is the most revealing. A builder who identifies genuine risks — the structural scope, the slab, the salt damp, the freight timelines — has read the project. One who says it all looks straightforward has not.
The Contract Payment Sequence
One WA-specific sequencing point worth stating plainly, because it is where homeowners most often lose their protection.
The order must be: verify registration → receive the Home Indemnity Insurance certificate → sign the contract → pay the deposit → work commences.
A builder who asks for a deposit before producing the certificate on work over $20,000 is asking you to do something that leaves you unprotected, and that they are not legally entitled to do. It is the single clearest warning sign available in this state, and it takes one question to test.