How Much Does a Builder Cost in Australia? Renovations, Decks and Extensions (2026)

Builders rarely quote by the hour. What you get is a fixed price for the whole project, and in 2026 that looks roughly like: a bathroom renovation $20,000 to $45,000, a deck $5,000 to $20,000, a ground-floor extension $2,500 to $4,500 per square metre. Here is how those numbers break down, what moves them, and how to compare quotes that look nothing like each other.

Prices are typical 2026 metro ranges including GST. Sydney sits at the top; regional areas can be lower on labour but higher on materials delivery.

Builder rates

The margin is how a builder makes money on a fixed-price job. It covers supervision, scheduling, insurance, warranty and profit. A quote with no visible margin is not cheaper - it is just less transparent.

Typical building project prices

Bathroom renovation: $20,000 - $45,000

• Cosmetic refresh (same layout, new tiles, vanity, tapware): $10,000 - $18,000
• Full renovation (strip out, waterproofing, new layout, mid-range fittings): $20,000 - $35,000
• High-end (stone, custom joinery, moved plumbing, underfloor heating): $35,000 - $60,000+

Waterproofing and tiling are the two items where cheap goes wrong expensively. See our tiling cost guide for what that part should cost.

Kitchen renovation: $20,000 - $50,000

Flat-pack cabinetry and laminate benchtops at the bottom, custom joinery and stone at the top. Moving the sink or the cooktop adds plumbing, electrical and possibly gas.

Timber deck: $250 - $500 per m²

A 20 m² treated pine deck is $5,000 to $8,000. Hardwood (spotted gum, merbau) or composite decking, elevated decks needing balustrade, and complex shapes push it to $400 to $500 per m² and beyond.

Pergola or verandah: $3,000 - $15,000

Freestanding timber pergola at the bottom. Attached, roofed, with lighting and council approval at the top.

Ground-floor extension: $2,500 - $4,500 per m²

A 40 m² extension is $100,000 to $180,000. Includes structure, roofing, windows, electrical and plumbing rough-in and standard finishes. Kitchens and bathrooms inside the extension are extra.

Second-storey addition: $3,500 - $6,000 per m²

Structural upgrades to the existing house, stairs, scaffold and living through it make second storeys the most expensive space to add.

Structural repairs: $2,000 - $30,000+

Underpinning, replacing bearers and joists, removing a load-bearing wall. Always needs an engineer’s report first ($500 - $1,500), and the price depends entirely on what the report says.

Licensing and insurance - the part that matters

Building licensing is state-based, and the thresholds are low:

• Queensland: licence required above $3,300
• Victoria: registered builder required above $10,000 (domestic building contract and insurance above $16,000)
• NSW: licence required above $20,000 (with home building compensation insurance)
• WA: registered builder above $20,000
• SA: licence required for all building work

Above these values the builder must be licensed, must give you a written contract and must arrange home warranty insurance. A quote from an unlicensed operator for a $30,000 job is not a bargain - it is a job with no warranty, no insurance and possibly no council approval.

Why builder quotes vary so much

Two quotes for “the same” bathroom can be $15,000 apart, and usually it comes down to:

• Scope. One includes demolition, waterproofing certification and rubbish removal. The other lists them as “by owner” or “if required.”
• Provisional sums and prime cost items. Allowances for tiles, tapware and fittings. A $30/m² tile allowance and a $90/m² allowance produce very different quotes for the same job.
• Margin transparency. Shown or hidden.
• Timeline. A builder who can start next week may be quiet for a reason - or may just have had a cancellation. Ask.

How to compare builder quotes

1. Write a scope of works before getting quotes - even a one-page list of what is in and out. Give every builder the same one.
2. Get three quotes. Post the job once with your scope, photos and any plans, and let local builders respond.
3. Ask for a breakdown: labour, materials, provisional sums, margin, preliminaries.
4. Check the licence on your state’s register, and ask for the insurance certificate.
5. Ask for recent references and go and look at a finished job if you can.
6. Read the contract. Progress payments should match completed stages. A large deposit (over 10 per cent in most states) is a warning sign.

Related guides

• Carpenter cost in Australia
• Tiling cost per square metre
• Roof restoration cost