Wondering what a granny flat will cost on your Perth block? As a rough guide, most turnkey builds in 2026 sit somewhere between $80,000 and $185,000 or more, depending on size, design, and your site. Every figure on this page is an estimate to help you budget, not a quote. The only way to know your real cost is a site-specific assessment. Since the April 2024 WA planning reforms removed the minimum lot size, more Perth blocks than ever can take one. Here’s how the numbers break down.
PLEASE NOTE
All prices on this page are indicative 2026 estimates intended for budgeting only. They are not quotes and do not form any offer or contract. Actual costs depend on your block, design, finishes and site conditions, and can only be confirmed by a tailored quote after a site assessment.
Key Takeaways
- Estimated turnkey granny flat costs in Perth typically range from about $80,000 for a basic one-bedroom unit to $185,000+ for a custom two- or three-bedroom design in 2026. All figures are estimates only.
- Size, site conditions, and finish level are the three things that move the price the most.
- A turnkey contract bundles design, permits, construction, and fit-out into one estimate, which makes budgeting clearer.
- Site works, service connections, and council permit fees can add to a base build estimate, so set aside a contingency.
- Demand is strong: “granny flat perth” is searched more than 8,100 times a month, and the number of builders competing is rising.
How Much Does a Granny Flat Cost in Perth?
As an estimate, a basic one-bedroom granny flat in Perth starts from around $80,000, while a custom two- or three-bedroom build with a full fit-out can sit between $150,000 and $185,000 or more. These are indicative 2026 ranges only. What you actually pay comes down to your block, your chosen design and the level of finish, so treat the table below as a budgeting starting point rather than a fixed price.
| Granny Flat Type | Approx. Size | Estimated Turn-Key Cost (2026) |
| 1-bed (entry-level) | ~48sqm | $80,000 to $110,000 |
| 1-bed (standard) | ~60sqm | $100,000 to $130,000 |
| 2-bed | ~65 to 70sqm | $130,000 to $160,000 |
| 2-3 bed (custom) | Up to 70sqm | $150,000 to $185,000+ |
The ranges above assume turn-key pricing, where design, permits, construction and fit-out are all included. Two builds of the same size can land at different prices once you factor in site conditions and finishes, which is why every estimate should be confirmed in writing. You can view the Classic WA granny flat designs to see which footprint suits your block, or read our complete granny flats Perth owner guide for the wider picture on rules, designs and timelines.
What’s Included in a Turn-Key Granny Flat Price?
A turnkey estimate usually covers the whole build from start to finish, so you can compare quotes on a like-for-like basis. The risk with cheaper headline prices is what they leave out. Some builders quote a low base figure, then add charges for the things that make the granny flat actually liveable. Always ask for a written list of inclusions and exclusions before you compare estimates.
Typically included
- Design and drafting of your plans
- Building permit application and documentation
- Slab, frame, roof and external cladding
- Standard kitchen, bathroom, flooring and internal fit-out
Often charged as extras
- Driveways, paths, fencing and landscaping
- Service connections (power, water, sewer or septic)
- Site works on sloping, sandy or tight-access blocks
- Upgraded fixtures, appliances or finishes above the standard range
What Affects How Much You’ll Pay?
Beyond the headline size, a handful of factors explain most of the gap between a $90,000 estimate and a $180,000 one. The biggest single driver is usually your site. A flat, sandy block with easy access is far cheaper to build on than a sloping or rear lot that needs extra earthworks and a crane.
Size and layout:
Size and bedrooms: every extra bedroom and bathroom adds cost.
Site conditions:
Slope, sand, drainage, demolition and access all change the site works needed.
Finishes:
Tiles, benchtops, appliances and joinery can swing the estimate by tens of thousands.
Services:
Distance to power, water and sewer connection points affects servicing costs.
What Extra Costs Should You Budget For?
On top of the base build estimate, it is sensible to budget for the surrounding costs that turn a finished shell into a working home. Your local council issues the building permit, and WA’s Building and Energy division sets the construction standards every dwelling must meet. As a rough rule, setting aside a contingency of 5 to 10 percent on top of your estimate gives you room for the unexpected, particularly on older or unusual blocks.
- Council building permit and application fees
- Connecting power, water, sewer or septic to the new dwelling
- Driveway, crossover, fencing and basic landscaping
- A 5 to 10 percent contingency for site surprises
Many Perth homeowners fund the build using equity in their existing home, and a granny flat can also generate rental income to help offset the cost over time. If you want to understand repayment options before you commit, take a look at the Classic WA finance options.
Frequently Asked Questions
How much does a granny flat cost in Perth in 2026?
As an estimate, turn-key granny flats in Perth range from around $80,000 for a basic one-bedroom unit to $185,000 or more for a custom two or three-bedroom design. These are indicative figures for budgeting; your actual cost is confirmed by a site-specific quote.
Is a one-bedroom or two-bedroom granny flat cheaper?
A one-bedroom granny flat is generally cheaper, with estimates from about $80,000, because it is smaller and simpler to build. A two-bedroom design typically sits from around $130,000. Both figures are estimates and depend on your block and finishes.
What’s usually not included in a granny flat price?
Cheaper estimates often exclude driveways, fencing, landscaping, service connections and site works on difficult blocks. Always ask for a written inclusions and exclusions list so you can compare quotes on a genuine like-for-like basis.
Can I finance a granny flat in Perth?
Yes. Many Perth homeowners draw on the equity in their existing property to fund a granny flat, and the rental income it can generate may help offset repayments. Speak to your builder and lender about options before you commit.