What Perth builders advertise in 2026
These are the builders' own published starting prices. They are a guide to the range, not quotes, and what's included differs.
| Builder (advertised) | Starting price | What it covers |
|---|---|---|
| Fox Granny Flats | From $119,000 (panel) or $145,000 (steel frame) | Starting prices; see their site for inclusions |
| Granny Flats WA | From $130,000 for a budget one-bed investor spec, move-in ready; can exceed $275,000 | Move-in ready at the budget end |
| Summit Granny Flats | 1-bed from $171,218; 2-bed from $183,555; 3-bed from $196,689 | Base build only. Finishes (about $15,000 for 50 m², $20,000 for 70 m²) and site works are extra |
One Perth builder puts construction at roughly $2,200 to $3,250 per m². For the largest granny flat that can skip planning approval (70 m²), that's about $154,000 to $227,500.
Costs on top of the build price
- Site works. Slope, soil, access for trucks and the distance to power, water and sewer. Builders say this is where most surprise costs come from, so get the site assessed before you sign.
- Finishes. Flooring, carpets, blinds, painting and air conditioning are not always in the base price.
- Bushfire (BAL) report and upgrades, if the lot is bushfire-prone.
- Verge bond. Many councils hold a refundable bond during building, for example $1,900 plus a $100 inspection fee at the City of Melville, or $2,200 plus a $140 admin fee at the City of Wanneroo.
The approval costs: worked examples
Every granny flat needs a building permit. The fees are set by the state, so they're the same at every council. For a granny flat lodged as an uncertified application (BA2), the permit is 0.32% of the value. The Building Services Levy is 0.137% for work over $45,000, and the Construction Training Fund levy is 0.2% for work over $100,000 (paid straight to the fund).
| Value of the build | Permit (BA2) | Building Services Levy | CTF levy | Total |
|---|---|---|---|---|
| $150,000 | $480.00 | $205.50 | $300.00 | $985.50 |
| $180,000 | $576.00 | $246.60 | $360.00 | $1,182.60 |
| $200,000 | $640.00 | $274.00 | $400.00 | $1,314.00 |
With a certified application (BA1) the permit fee drops to 0.19%, but you also pay a private building surveyor. Plans, engineering and the energy efficiency report are usually part of the builder's price.
A granny flat of up to 70 m² that meets all the standard planning rules doesn't need planning approval, which saves a fee and up to 60 days. See when you can skip planning approval.
Sources
- How much does a granny flat cost in WA? (Summit Homes, July 2026)
- Fox Granny Flats
- Granny Flats WA
- Granny flat cost in Perth 2026 (Boda Building Group)
- Building Regulations 2012 fees from 1 July 2026 (City of Fremantle)
- Building approvals and the Building Services Levy (WA Government)
- Construction Training Fund levy
- Building a shed or outbuilding: verge bond (City of Melville)
- Patios information sheet with verge bond fees (City of Wanneroo)