How to Choose a Granny Flat Builder

Start with licence verification — always

Licence registration is the one fact a prospective builder cannot fudge. Every Australian state publishes an online register where you can search a name or ABN and see current licence status, the scope of work permitted, and any disciplinary history.

• NSW: service.nsw.gov.au — "Check a builder or tradesperson licence"
• VIC: vba.vic.gov.au — "Find a practitioner"
• QLD: my.qbcc.qld.gov.au — "Licensee register"

Search the company name and the individual builder's name separately. A common pattern with unscrupulous operators is that the company trades under a director who is not personally licensed — or whose licence has been suspended. If the name on the quote does not match the name on the register, ask why.

Membership of an industry body — HIA, Master Builders, or a state chapter — is a signal of engagement, not a consumer guarantee. Check the licence first. Industry body logos second.

Confirm home warranty insurance is actually in place

Home warranty insurance (the precise name varies by state) protects you if the builder becomes insolvent, dies, or disappears before the job is finished or before the defects period expires. Alongside granny flat rules and planning approval, it is the most important consumer protection on a residential building contract.

The thresholds and names:

• NSW: Home Building Compensation (HBC) is required for any residential works over $20,000. Every granny flat project qualifies.
• VIC: Domestic Building Insurance (DBI) is required for works over $16,000.
• QLD: Home Warranty Insurance (HWI) through the QBCC scheme is required for works over $3,300 — effectively every granny flat build in Queensland.

Ask the builder to provide a certificate of insurance for your specific project before you pay a deposit. The certificate is issued once the builder lodges your contract with the insurer. If the builder tells you insurance will be sorted "after" you sign, that is a warning sign, not a scheduling detail.

Request at least three past project references

Ask for three completed granny flats you can visit or call about. A legitimate builder will have this list ready — they know references close deals. Insist on granny flats specifically, not full house builds, because the site-cost dynamics are different on a 60sqm secondary dwelling.

When you call references, ask three questions:

1. How closely did the final price match the original quote?
2. How did the builder handle the first major problem on site?
3. Would you use them again?

The second question matters most. Every build has at least one problem — a soil test surprise, a council request for information, a delayed product. A good builder tells you about the problem, offers options with prices, and moves on. A bad builder disappears, blames the owner, or issues surprise variations that arrive with an invoice attached.

Compare itemised quotes, not lump-sum totals

Three granny flat builders will quote your project three different ways. Some will hand you a single figure. Others will break out the base build package, the site costs, the professional fees, and the authority charges. Only the itemised quote lets you compare builders fairly.

Insist on line items for the four cost buckets every granny flat project has to pay for:

1. Base build package — the structure and internal fit-out
2. Site works — earthworks, slab, retaining walls, tree removal, service runs
3. Professional and approval fees — design, engineering, BASIX (NSW), CDC or DA lodgement
4. Authority and utility charges — sewer and water compliance, electrical upgrades, infrastructure charges where applicable

If one builder's quote is $40,000 cheaper than another's, the difference is almost always sitting in one of these four buckets. Without line items, you cannot tell which bucket — or whether you are looking at a better deal or at items that have simply been left out to make the headline number look competitive.

For a deeper walkthrough of what drives these numbers, see the granny flat building costs breakdown and the guide to published granny flat prices — both explain how builder pricing is put together and what is typically excluded.

Check council liaison is included in the scope

A turnkey build should include everything from site assessment to handover. Council lodgement — a CDC in NSW, a building permit in Victoria, or accepted development lodgement in Queensland — should not be something you do yourself unless you are on an owner-builder pathway. If the builder's scope excludes council lodgement without reducing the price accordingly, that is a margin pad and a warning sign.

For NSW projects where the CDC approval pathway is available, confirm the builder has a preferred private certifier they work with and that the quoted fee covers lodgement and any certifier requests for information. For Victorian projects, confirm the builder handles the building permit application through a registered building surveyor. In Queensland, ask whether the project falls under accepted development for the specific council or whether a DA is required — the answer materially changes the timeline.

Review the contract payment schedule line by line

Deposit caps exist precisely because large upfront payments are the most common way consumers lose money on residential building projects. In NSW, the law limits deposits on residential building contracts over $20,000 to 10% of the contract price or $20,000, whichever is less. A builder asking for 30% up-front on a granny flat is not "just how it is done" — it is breaching the consumer protection that exists on paper specifically to stop that behaviour.

A reasonable progress payment schedule looks like this:

• Deposit on signing: up to 10% (capped in NSW)
• Base stage (slab complete): 10–15%
• Frame stage (framing complete): 20–25%
• Enclosed stage (roof, windows, external cladding): 20–25%
• Fixing stage (internal fit-out, tiling, painting): 20–25%
• Practical completion: 5–10%

Never pay ahead of stage. If the builder asks for a frame payment before the frame is up, decline politely and point to the contract. Stage payments are not a formality — they are the mechanism that keeps the builder honest, because they do not get the next tranche until the work is actually done.

Confirm the defects liability period

The defects liability period is the window after practical completion during which the builder must return to fix issues at no charge. Six months is the typical minimum on a residential contract; twelve months is better. In NSW, the statutory warranty period is 6 years for major defects and 2 years for other defects — the defects liability period in the contract sits in addition to those statutory warranties, not as a replacement.

Make sure the contract specifies:

• The length of the defects liability period
• How defects are reported (in writing, within what timeframe)
• Response time for major defects (72 hours for anything affecting habitability is reasonable)
• Final payment withheld until defects are resolved

Red flags — when to walk away

Some behaviours should end a builder conversation immediately, regardless of the quote price or how charming the sales rep was.

• No fixed-price contract. Cost-plus arrangements on a residential granny flat are almost always a worse deal for you than a fixed price with a realistic contingency.
• Demands for a large upfront payment. Anything over 10% breaches NSW law and is questionable practice in every state.
• No ABN or licence number on the quote. Both should be printed on every page of every document you receive.
• Pressure to sign today. "This price is only valid this week" is a classic closing technique used on people who do not have time to verify.
• Cash-only discount offers. They void warranty insurance and break the consumer protection chain entirely.
• Verbal promises that do not make it into the written contract. If it is not in writing, it does not exist. Get every inclusion, every exclusion, and every allowance into the contract before you sign.

Questions to ask at the quoting stage

Print this list. Take it to every quoting meeting:

1. What is your current licence number, and where can I verify it?
2. Will you provide a certificate of home warranty insurance for my project before I pay a deposit?
3. Can I visit a completed granny flat you built in the last 12 months?
4. Is the quote itemised across base build, site works, professional fees, and authority charges?
5. What site costs are excluded — retaining walls, tree removal, service connection runs?
6. Who lodges the CDC, DA, building permit, or accepted development paperwork?
7. What is the deposit, and what are the progress payment stages?
8. How long is the defects liability period, and how are defects reported?
9. What happens if the job runs late — is there a liquidated damages clause?
10. Can I have 48 hours to review the contract with a solicitor before signing?

If a builder hesitates on question ten — the solicitor review — that is a quiet red flag on its own. Legitimate builders expect contract review. It is a normal part of every significant construction project.

What the vetting process tells you about the builder

By the time you have worked through licence, insurance, references, itemised quote, and contract review, you already know whether this is a builder you want on your property for the next four to six months. These checks are not a bureaucratic hurdle — they are the first real test of how the builder will handle your project when something inevitably goes wrong.

A builder who walks you through licence and insurance without prompting, volunteers references before being asked, and itemises every cost bucket by default has already told you, through their behaviour, what working with them will be like. A builder who resents the questions has told you exactly the same thing.

GrannyFlatGuide is an independent resource — our about page explains how we stay that way. We do not accept payment from builders in exchange for directory placement or favourable coverage. Use the checklist above with any builder you are considering, including ones we connect you with.

A note on scope

This page is general consumer guidance, not legal advice. Building contracts are enforceable agreements with real financial consequences. For contracts over $100,000 — which describes most turnkey granny flat projects — a one-hour review by a building-and-construction solicitor typically costs $300–$600 and often saves many times that in variation disputes and scope disagreements later. GrannyFlatGuide does not provide legal, planning, or building advice. Verify licence and insurance details directly with the relevant state regulator before making decisions.