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What a granny flat costs in Perth
Typical 2026 market prices, the site costs people forget, and how we price.
Granny flat prices in Perth vary with size, finishes and the block. The figures below are independent 2026 market ranges for the Perth metro area, including GST, so you can sense-check any quote, including ours.
| Type | Typical size | Typical range |
|---|---|---|
| Studio or one bedroom, turnkey | 35 to 45 m² | $110,000 to $160,000 |
| Two bedroom, turnkey | About 60 m² | $140,000 to $210,000 |
| Custom or premium two bedroom | Up to 70 m² | $210,000 to $320,000 |
| Prefab or modular one bedroom, delivered | Varies | $80,000 to $120,000Plus site works and connections |
Source: What's The Damage, Perth granny flat cost guide, October 2026. Market ranges, not our prices.
Costs on top of the building
| Item | Typical range |
|---|---|
| Site works and service connections (water, sewer, power) | $15,000 to $40,000 |
| Building permit and R-Codes assessment | $3,000 to $11,000 |
| Demolition or site clearing, if needed | $3,000 to $15,000 |
| Driveway, paths and basic landscaping | $5,000 to $20,000 |
Source: What's The Damage, Perth granny flat cost guide, October 2026.
What moves the price
- Distance to sewer and power. A long trench or a sewer connection at the back of the lot adds cost.
- Crane access. A short, easy lift costs less than lifting over a two-storey house or using a bigger crane.
- Slope and soil. Sloping blocks and poor soil need more earthworks and footings.
- Bushfire-prone areas. A higher BAL rating adds construction requirements.
- Size and finishes. The biggest lever is the design you choose.
How we price
After the free site visit we send one fixed price in writing, under a WA home building contract. It covers the granny flat, delivery and crane, the slab, the building permit application and the service connections we can see on site. If something needs a provisional sum, such as an unknown sewer depth, we tell you up front and explain it.
Common questions
Is a factory-made granny flat cheaper?
Often, because the building is made efficiently in a factory and less time is spent on site. You still pay for the slab, delivery, crane and connections, so compare total prices, not just the building.
Is a granny flat cheaper than an extension?
Often similar per square metre, but a granny flat is fully self-contained with its own kitchen and bathroom. It can also earn rent, which an extension usually can't.
See what fits in your backyard
Book a free site visit. A registered builder checks your block, access and services, then sends a fixed-price quote.