How to Quote a Granny Flat Build in Australia
A granny flat is a full house build in miniature — slab, frame, lock-up, fit-out and every service connection. Here's how to quote one by stage so nothing's missed and the progress payments protect you.
A granny flat is a whole house build compressed into 40 to 60 square metres — slab, frame, roof, lock-up, rough-in, lining, fit-out and every service connection, all needing approvals and inspections. The quotes that come unstuck are the ones that priced the building and forgot the sewer connection or the council fees. This guide breaks a granny flat quote into stages, sets out 2026 costs, and shows how progress payments keep you covered across a build that runs for months.
Quoting a granny flat by stage
The clearest way to quote a granny flat is stage by stage, each with its own subtotal. It mirrors how the build actually runs and it lines up neatly with your progress payments:
- Site works and slab — clearing, earthworks, footings and the concrete slab.
- Frame and roof — wall frames, trusses and roof cover to weathertight.
- Lock-up — windows, external doors and cladding so the shell can be secured.
- Rough-in — plumbing, electrical and any HVAC run through the frame.
- Internal lining — insulation and plasterboard.
- Fit-out — kitchen, bathroom, flooring, paint and fixtures.
- External works — landscaping, driveway and fencing.
Present each stage with its own subtotal rather than one lump sum. It's easier for the client to follow, easier to adjust when they change a finish, and it maps directly onto the payment milestones.
Granny flat costs in 2026
Granny flat pricing is usually framed per square metre, landing between $2,500 and $4,500/m² depending on finish. As whole-of-build figures:
| Build | Size | Typical cost |
|---|---|---|
| Basic 1-bedroom | 40m² | $100,000–$150,000 |
| Standard 2-bedroom | 60m² | $150,000–$220,000 |
| Premium finish | 60m² | $200,000–$300,000 |
These figures include all trades, approvals and site connections but exclude the land value. Make that exclusion explicit in the quote — and remember the per-m² rate assumes a straightforward site, which is exactly what a slope or poor access will undo.
Council approval: CDC vs DA
How the build gets approved changes both cost and timeline, so check eligibility before you put a number on the approvals line. In NSW the two paths are:
- Complying Development Certificate (CDC) — available for granny flats up to 60m² that meet the criteria (lot size, setbacks, floor space ratio). Faster at 10–20 business days and cheaper at $2,000–$5,000.
- Development Application (DA) — required when the CDC criteria aren't met. Budget $5,000–$15,000 and 3–6 months.
- Either way, put the approval and certification fees in as their own line so the client sees they're a genuine cost, not your markup.
Progress payments across the build
A granny flat runs 12–20 weeks through multiple trades and inspections. Structuring the quote with progress payments tied to milestones keeps your cash flow ahead of your costs and protects the client too:
| Milestone | Payment |
|---|---|
| Deposit | 10% |
| Slab completion | 15% |
| Frame and roof | 20% |
| Lock-up | 20% |
| Rough-in | 10% |
| Practical completion | 25% |
Common mistakes that eat your margin
- Leaving out service connections. Connecting sewer, water and electrical can run $5,000–$20,000 and is the single biggest surprise on most granny flat quotes. Price it before you commit.
- Underestimating site preparation. Clearing, cut-and-fill and access works vary hugely with the block. A flat, clear site and a sloping, tight one are not the same job.
- Forgetting council and certification fees. Approvals, certifiers and inspections are real costs with real lead times. Leave them out and they come off your margin.
- Skipping the external works. Landscaping, driveway and fencing are easy to forget and expensive to absorb once the client expects a finished job.
- Quoting without a site assessment. Slope, access and where the services run all change the price. A proper assessment — ideally a survey and geotech report — comes before the number.
Pro tips for a granny flat quote that holds
- Do a thorough site assessment, including a survey and geotech report, before you price.
- Include service connection costs up front — they're the biggest surprise on most jobs.
- Structure the quote around progress payment stages tied to milestones.
- Check CDC eligibility before you quote the slower, dearer DA path.
- Attach a preliminary timeline with the key milestones marked.
- Carry a variations allowance for unexpected ground conditions.
ServiceYak keeps your stage rates, approval fees and connection costs in a reusable kit, so you can build a staged granny flat quote with milestone payments and send the PDF the same day you assess the site.
Frequently asked questions
How much does it cost to build a granny flat in Australia?
Roughly $2,500–$4,500/m², or about $100,000–$150,000 for a basic 1-bedroom (40m²) and $150,000–$300,000 for a 60m² build depending on finish. Those figures include trades, approvals and connections but exclude the land.
Do I need a DA or can it be a CDC?
In NSW a granny flat up to 60m² can often go through a CDC if it meets the lot size, setback and floor space criteria — faster and cheaper than a DA. If it doesn't meet them, a DA is required, adding cost and months to the timeline.
How long does a granny flat take to build?
Around 12–20 weeks through the trades and inspections, on top of the approval time — 10–20 business days for a CDC, or 3–6 months for a DA. Build that approval window into the timeline you show the client.