What should your build cost?

A ballpark for a new home, extension, second storey or granny flat from published building prices, checked against Canberra builders, and the ACT rules that come with a big job.

1What are you building?

2How big is it?

Floor area built, measured to the outside of the walls. Don't count a garage or deck.

Area (m²)

3What level of finish?

Standing by

$— – $—

ACT rules

ACT rules for a big build

Granny flats: in the ACT a granny flat is a secondary residence. It can only go with a single house, can be up to 90 m² (measured to the outside of the walls, not counting a garage), can be up to two storeys, and there can be one per block. It can't be sold or titled separately, and if your Crown lease allows only one dwelling you'll need a lease variation. Check whether yours needs a development application.
Builder insurance: residential building work insurance covers houses and apartment buildings of three storeys or less, and protects you and future owners if the builder dies, disappears or goes broke. The minimum cover rose from $85,000 to $200,000 on 1 January 2025. In the ACT it comes from QBE or the Master Builders Fidelity Fund, and the builder arranges it.
Approvals: new homes, extensions and second storeys usually need building approval, and many need a development application. ACT Planning's checkers tell you which applies to your block.

From Territory Plan 2023, E01 Residential Zones Policy (NI2023-540) and ACT Planning: Case study, Grant and his granny flat and ACT Planning: Residential building work insurance and ACT Planning: Builders' responsibilities and ACT Planning: Check if you need a building approval and ACT Planning: Check if you need a DA (checked 22 Oct 2026). A guide, not legal advice: check the source before you rely on it.

Cross-checked

3 of 3 independent prices agree

Most published trade prices trace back to one guide, so we check our numbers against any independent source we can find.

New home, per m²Rawson Homes (Canberra): $2,150–$4,200. Roughly: $1,600–$4,500.inside our range
Single-storey extension, per m²Rentoule Projects (Canberra): $3,200–$5,200. Roughly: $2,500–$5,000.overlaps our range
2-bed granny flat, about 60 m², build onlyCanberra Granny Flat (Canberra): $145,000–$195,000. Roughly: $138,000–$210,000.inside our range

From Rawson Homes: Building costs Canberra 2026 (citing Rider Levett Bucknall), Rentoule Projects: Home extension costs in Canberra, Canberra Granny Flat: Granny flat prices in Canberra 2026.

Licensed work

Check their licence

Building work that needs building approval has to be done or supervised by a licensed builder in the ACT, and for a house build or a renovation worth $12,000 or more they must also hold residential building insurance for you. Ask for their licence number, then look them up on Access Canberra's public register. It shows expired, suspended and cancelled licences, and any disciplinary action.

Access Canberra: choosing a tradesperson →