Cost guides › Attic conversion
Australia
Attic conversion cost: a habitable room in the roof
Converting 30 m² of roof space into a habitable room typically costs $95,100 including GST, with most quotes between $74,100 and $123,600. That covers approvals, engineering and certification, a strengthened floor, insulation and plasterboard, a fixed staircase, three roof windows, electrics and a finished room. A simpler fit-out is about $84,400, and a premium version with better insulation, timber floors, built-in storage and larger roof windows is around $110,300.
Most homeowners pay
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Cost by region
| Location | Basic | Mid-range | Premium |
|---|---|---|---|
| Australian Capital Territory | $89,300 | $100,600 | $116,600 |
| Western Australia | $86,700 | $97,700 | $113,300 |
| Northern Territory | $85,600 | $96,400 | $111,900 |
| New South Wales | $85,000 | $95,800 | $111,200 |
| Queensland | $83,700 | $94,300 | $109,500 |
| Victoria | $83,600 | $94,200 | $109,400 |
| South Australia | $80,600 | $90,900 | $105,600 |
| Tasmania | $78,200 | $88,100 | $102,500 |
What's included
Mid-range
- Council approval or complying development, engineering and certifier fees
- New or strengthened floor structure with sheet flooring
- Insulation to the roof and walls, plasterboard linings and finish
- Fixed staircase from the floor below
- Three roof windows, flashed and fitted
- Electrical circuits, lights and power points
- Flooring, doors, skirting and painting
What affects the cost
Roof framing
Houses with a traditionally pitched (cut) roof, common in older Sydney and Melbourne homes, are the easiest to convert. Modern trussed roofs are full of web members and usually need an engineer-designed replacement structure, which costs much more.
Ceiling height
A habitable room needs enough ceiling height over most of its floor. Low-pitched roofs often only allow a storage room, and your certifier will confirm what the building rules allow before you commit.
Stairs
A proper staircase is what turns roof storage into a room you can live in. It needs space on the floor below, and fitting it without losing a bedroom or hallway is the main design challenge.
Heat in summer
Roof spaces get very hot. Good insulation, sarking, ventilation and roof windows that open or shade are what make the room usable in January; plan cooling from the start.
Approvals
Most councils treat a new habitable room in the roof as work that needs approval, either a development application or complying development with a private certifier. Fees and engineering are a noticeable share of the budget.
How to save
- Ask a certifier or attic specialist to confirm the room can be habitable before paying for full drawings.
- Keep the roofline unchanged; adding dormers or lifting the roof moves the job into a different price range.
- Choose roof windows over custom glazing and keep plumbing out of the roof space.
- Get three itemised quotes covering approvals, stairs and windows so you can compare like with like.
Grants, tax and rules
Licensed trades and GST
Electrical and plumbing work must be done by licensed tradespeople under state licensing. Quotes to households include 10% GST, and so do our figures. Check with your council or a private certifier which approval pathway applies to your house.
Frequently asked questions
How much does an attic conversion cost in Australia?
A habitable attic room of about 30 m² with stairs, roof windows, insulation and approvals costs around $95,100 including GST. A simpler fit-out is about $84,400 and a premium one around $110,300.
Can I convert my roof space into a bedroom?
Only if the roof is high enough and the structure can be adapted. Older houses with pitched cut roofs are the best candidates; modern trusses and low-pitched roofs often only allow storage.
Do I need council approval for an attic conversion?
Usually yes when you create a habitable room, because it involves structure, stairs and fire safety. Your council or a private certifier will tell you whether a development application or complying development applies.
Is a storage attic much cheaper?
Yes. A lined, floored storage room with a ladder costs a fraction of a habitable room because it needs no fixed stairs, approvals for a bedroom or full insulation.
How long does an attic conversion take?
Building work usually takes six to ten weeks, but approvals can add several months before work starts.
How this estimate is calculated
Work hours: 543.5 · Labour: $50,150 · Materials: $36,262
Sources: ABS Employee Earnings and Hours, Australia; Regione Toscana, Prezzario dei Lavori 2026 (CC BY 4.0); ECB exchange rates; market check: Habitable attic room ~30 m2 with roof windows and stair, incl. GST. hipages attic renovation guide (updated Dec 2024: $80-100k habitable conversion, DA $5-10k); sydneyatticconversion.com.au FAQ ($70-120k one-bedroom loft); Inner City Attics Sydney 2026 guide (DA-approved bedroom $120-200k+).
Last reviewed 26 September 2026 · How we calculate costs · Editorial policy