How much does a builder cost in Perth?
Perth builders price most work either by the square metre or as a whole project. Extending at ground level runs $2,500–$5,000 per square metre, with a usual figure of $3,500, and building a new home to a standard finish $1,600–$4,500. Whole projects sit higher: a turnkey one- or two-bedroom granny flat costs $120,000–$250,000, adding a level $250,000–$600,000, and a single-storey knock-down rebuild of three or four bedrooms $450,000–$1,000,000. Detached living is the norm here: 77.8% of dwellings are separate houses, and 45.7% of homes have at least four bedrooms, a share well above the 34.8% recorded across Australia (ABS 2021 Census). Every price includes GST.
Comparing cities, or after the Australia-wide picture? See the national guide: Builder cost in Australia.
Detailed Pricing — Building Cost in Perth 2026
| Service | Low | Typical | High |
|---|---|---|---|
| Minor structural repair (lintel, crack stitching, wall ties) | $500per job | $1,800 | $5,000 |
| Load-bearing wall removal + steel beam | $3,000per job | $8,000 | $15,000 |
| Pre-purchase building inspection / defect report | $400per job | $600 | $1,200 |
| Deck or pergola (builder-managed) | $5,000per project | $12,000 | $40,000 |
| Roofed patio / alfresco (builder-managed) | $12,000per project | $20,000 | $35,000 |
| Garage or carport (single to double) | $10,000per project | $25,000 | $55,000 |
| Bathroom renovation (builder-managed) | $15,000per project | $25,000 | $45,000 |
| Kitchen renovation (builder-managed) | $20,000per project | $35,000 | $70,000 |
| Single-storey extension (per sqm) | $2,500per sqm | $3,500 | $5,000 |
| New home build (per sqm, standard finish) | $1,600per sqm | $2,300 | $4,500 |
| Granny flat (1-2 bed, turnkey) | $120,000per build | $165,000 | $250,000 |
| Full home renovation (whole house) | $150,000per project | $300,000 | $600,000 |
| Second-storey addition | $250,000per project | $380,000 | $600,000 |
| Knock-down rebuild (3-4 bed, single storey) | $450,000per build | $650,000 | $1,000,000 |
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Get Perth quotes →Renovate, Extend or Rebuild in Perth?
In the Perth table a full renovation is $150,000–$600,000, an extension $2,500–$5,000 a square metre and a rebuild $450,000–$1,000,000. Home indemnity insurance is required for permitted work over $20,000, covering a lost deposit up to $40,000 and defective work up to $200,000.
Common Building Projects and What They Cost
Home extensions
30–50 m² extension: $75,000–$250,000.
Second-storey additions
Adding a level: $250,000–$600,000.
Granny flats
A turnkey granny flat: $120,000–$250,000.
Knock-down rebuilds
Knock-down rebuild: $450,000–$1,000,000, after a demolition permit.
Home Extensions and Second-Storey Additions in Perth
Builders on work of $20,000 or more must be registered. Selling an owner-built home within seven years needs home indemnity insurance or it’s an offence. Second storey: $250,000–$600,000.
Knock-Down Rebuild vs Renovation in Perth
A WA demolition permit (BA5) for a house is $121 plus the levy (fee as of August 2026); the City of Perth issues it within 10 business days, with a dilapidation survey of the neighbours and a licensed demolition contractor. Rebuild $450,000–$1,000,000.
What's Included in a Builder's Quote
WA caps the deposit at 6.5% on contracts of $7,500–$500,000, and progress payments can cover only work done. A pre-purchase inspection is $400–$1,200 in our table.
What Affects Builder Costs in Perth
Registration and home indemnity
In most of Western Australia a builder taking on building work worth $20,000 or more must be registered with Building and Energy. Permit work above $20,000 must also carry home indemnity insurance, which the builder takes out in your name, handing you the certificate before any deposit is requested or a spade goes in. That policy can cover a lost deposit up to $40,000 and incomplete or defective work up to $200,000.
What the deposit can be
WA home building contracts between $7,500 and $500,000 have to be written down and signed by owner and builder, and the most a builder can take up front is 6.5 per cent. On a builder-run bathroom at a typical $25,000, that is about $1,625. Kitchens can differ: where off-site cabinetry is more than half the contract, the builder may ask up to 20 per cent. Each progress claim should then cover only work actually done.
Garages, carports and patios
A Class 10a building in WA, such as a garage, carport, shed or patio, valued under $50,000 does not need a registered building contractor, and home indemnity insurance on a Class 10 starts at $50,000 rather than $20,000. The full roofed patio band in our table, $12,000–$35,000, falls under that line. Building only a pergola, fence or pool counts as associated work, which needs no home indemnity cover.
Wet winters, scorching summers
The Perth Metro station records 147 mm of rain in July and more than 125 mm in each of June and August, against 9.6 mm in December, while days in January and February average more than 31 °C (BOM averages). Footing and slab pours wait out wet weeks, and a second-storey job leaves the roof open for a stretch, so builders programming those stages through winter often allow extra weather days.
Before a knock-down
WA allows no demolition without a demolition permit, whether the building is a house or an outbuilding (a Class 1 or Class 10 building); ask the City for its current fee. In the City of Perth the permit is issued within 10 business days, the application includes a dilapidation survey of buildings next door, and work waits until services are disconnected or sealed. WA Health says to use a licensed asbestos removalist for any removal, so ask how the quote treats asbestos.
Soil, structure and energy rules
Footings are priced from the soil classification and the engineer's drawings, so quotes made before either exists are only rough estimates. A steel beam in place of a load-bearing wall costs $3,000–$15,000, and lintel, crack or wall-tie repairs $500–$5,000. Under the NCC, Perth falls in climate zone 5 (warm temperate), and any extension must meet that zone's insulation and glazing rules.
How to Save Money on Building Cost in Perth
Frequently Asked Questions — Building Cost in Perth
Our Methodology
Prices on this page are compiled from publicly available cost guides, leading tradie marketplaces, peak industry body data, and individual tradesperson websites across Australia. We cross-reference ranges from multiple sources and adjust for city-specific cost differences. Our price guides are produced independently and no tradesperson can influence a published figure. All prices are estimates and will vary based on your specific job. Always get multiple quotes. Last reviewed June 2026. Read our full methodology →