How much does a granny flat cost in Perth?
A granny flat in Perth costs $105,000–$152,000 for a turnkey 1-bedroom build (35–45m²), $133,000–$200,000 for a 2-bedroom (around 60m²), and from about $76,000 supplied for a prefab or kit unit. Per square metre, turnkey builds run $2,200–$3,350/sqm depending on design, site, and finishes.
Detailed Pricing — Perth 2026
| Service | Low | Typical | High |
|---|---|---|---|
| Prefab / kit granny flat — 1-bed (supplied) | $76,000total | $90,000 | $114,000 |
| Studio / 1-bed granny flat (35-45m², turnkey) | $105,000total | $124,000 | $152,000 |
| 2-bed granny flat (~60m², turnkey) | $133,000total | $166,000 | $200,000 |
| Custom / premium 2-bed (high-end finishes) | $200,000total | $247,000 | $304,000 |
| Two-storey or with attached garage | $266,000total | $328,000 | $404,000 |
| Garage / outbuilding conversion | $38,000total | $71,000 | $114,000 |
| Turnkey build (per m² built) | $2,200/sqm | $2,650 | $3,350 |
| Site works + service connections | $14,000total | $24,000 | $38,000 |
| Building permit + R-Codes assessment | $3,000total | $6,000 | $11,000 |
| Demolition / site clearing (if needed) | $3,000total | $6,000 | $14,000 |
| Driveway, path & basic landscaping | $5,000total | $10,000 | $19,000 |
| Privacy fencing (per m) | $140/m | $210 | $290 |
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Get Perth quotes →Prices include GST. Based on Perth metro area, Mar 2026. Outer suburbs may vary.
Perth’s Granny Flat Market in 2026
Perth has one of Australia’s busiest granny flat markets. High property prices, multi-generational living, and strong rental demand make a secondary dwelling one of the higher-return additions a Perth homeowner can make — a 2-bedroom granny flat rents well and can lift property value by 10–30%. WA has steadily relaxed its ancillary-dwelling rules, and Perth’s big suburban blocks make a detached granny flat one of the easiest backyard builds in the country.
The biggest swing in price is build method. Prefab and modular units (from about $76,000 supplied) are the budget end; standard site-built 1- and 2-bedroom homes ($105,000–$200,000 turnkey) are the mainstream; and custom or two-storey builds run $200,000–$404,000+. Site works and service connections ($14,000–$38,000) and approvals are the costs homeowners most often underestimate.
On the rules: In WA an ancillary dwelling (granny flat) of up to about 70m² can generally be approved and rented out, assessed against the R-Codes — confirm requirements with your local government. Build method, finishes and the R-Codes assessment shape the price, plus site works.
We’ve compiled pricing from Perth granny flat builders, prefab suppliers, and trade databases to give the most accurate picture of granny flat costs in Perth for 2026.
How Granny Flat Costs Vary Across Perth
Western Suburbs
Typical cost: $171k–$314k turnkey
Cottesloe, Claremont, Nedlands, Subiaco, Dalkeith. Perth’s most expensive area. Premium finishes to match high-value homes; budgets run to the top of the range.
Northern Coastal
Typical cost: $152k–$285k turnkey
Scarborough, Hillarys, Joondalup, Sorrento. Big coastal blocks suit detached 2-bed builds; sea-air sites benefit from corrosion-resistant detailing. Strong rental demand.
Southern Suburbs
Typical cost: $143k–$266k turnkey
Fremantle, Rockingham, Baldivis, Cockburn. A mix of heritage Fremantle lots and newer southern estates. Access and block type drive the price.
Eastern Suburbs
Typical cost: $114k–$219k turnkey
Midland, Guildford, Forrestfield, High Wycombe. More affordable, flatter blocks with easy access. Standard single-storey and prefab builds are the staple.
Hills & Outer
Typical cost: $114k–$219k turnkey
Kalamunda, Mundaring, Ellenbrook, Byford. Large blocks suit bigger builds; bushfire-prone hills areas need BAL-rated construction, which adds cost.
What You’ll Actually Pay — Common Perth Granny Flat Builds
Here’s what typical granny flat projects cost all-in across Perth in 2026, including build, standard site works, services, and approvals where noted.
1-bedroom granny flat — 40m², turnkey
$105,000–$143,000 total
The go-to Perth build for one tenant or a family member. A detached one-bedroom home — bedroom, bathroom, kitchenette and living — with standard finishes, slab and connections. Allow roughly 12–14 weeks once approval is through.
2-bedroom granny flat — 60m², turnkey
$143,000–$200,000 total
The strongest rental option — two bedrooms, a full bathroom and a real kitchen. Standard-to-mid finishes with slab, services and approval rolled in. Budget 14–16 weeks of build time once approved; it’s the bread-and-butter Perth investment build.
Prefab / modular 2-bed — installed
$90,000–$152,000 total
Factory-built and craned in, then connected to services on a prepared slab. Faster than site-built and priced lower, with less on-site disruption. Site works, slab and connections are usually quoted on top of the supplied unit price.
Garage / outbuilding conversion to studio
$43,000–$90,000 total
Converting an existing garage or outbuilding is the cheapest route to a secondary dwelling, but plumbing, a bathroom and kitchenette, insulation, glazing and compliance upgrades drive the price. Best value where the existing slab and walls are sound.
Custom architect 2-bed / two-storey
$247,000–$404,000 total
A top-end, architect-designed build — premium finishes, a bigger footprint or a two-storey layout on a tight block. Design and engineering are required; you’ll see these most across the coastal northern and southern suburbs where land values justify the outlay.
What Affects Granny Flat Costs in Perth
Build method
The cheapest path is a prefab/kit unit (from ~$76,000 supplied); a standard site build is the middle ground, and custom or two-storey designs sit at the top.
Size & bedrooms
Expect $105,000–$152,000 for a turnkey 1-bed (35–45m²) and $133,000–$200,000 for a 2-bed (~60m²) — 60m² being the usual size cap.
Site works & access
Slope, rock, poor access and craneage add $14,000–$38,000. Flat, clear, easy-access blocks are far cheaper to build on.
Service connections
Water, sewer, power and stormwater connections add cost — keeping wet areas near the main house’s services keeps plumbing runs short.
Approvals
In WA an ancillary dwelling (granny flat) of up to about 70m² can generally be approved and rented out, assessed against the R-Codes — confirm requirements with your local government.
Finishes & inclusions
Standard finishes keep costs down; stone benchtops, premium flooring, decks and air-conditioning push a build toward the top of the range.
How to Save Money on a Granny Flat in Perth
Frequently Asked Questions
Our Methodology
Our pricing comes from a mix of sources — public cost guides, tradie marketplaces, peak-body rate data, and individual builder sites — cross-referenced and then adjusted for regional cost differences. We produce these guides independently, and no tradesperson can buy their way onto the page or sway a figure. Every price is an estimate that will move with the details of your job, so we always recommend getting multiple written quotes. Last reviewed June 2026. Read our full methodology →