How much does an attic conversion cost in 2026? – Price guide

What does an attic conversion cost?

Our calculator uses a Swedish baseline of about SEK 15,000 per square metre excluding VAT for a standard conversion with insulation, walls, floor, electrics and finishes. It is converted for the country you choose.

Simple attics with good head height and an existing staircase cost less. Dormers, a bathroom or floor reinforcement push the price up.

Labour rates and rules differ a lot between countries, so always compare against local quotes.

What drives the cost?

Head height and floor joists: living space needs enough head height, and old joists often need strengthening to carry a floor and furniture.

Insulation and ventilation: the roof must be insulated and ventilated correctly to avoid moisture and mould.

Dormers and roof windows: they add light and standing room but are among the most expensive items.

Staircase: a new stair takes space on the floor below and may require cutting through the floor structure.

Fire safety, electrics and heating: fire-rated materials, new wiring and heating are usually needed.

Do you need planning permission?

Converting the inside of an attic often needs no planning permission as long as the exterior is unchanged, but building regulations still apply.

Dormers, new roof windows or a changed roof shape alter the exterior and often require permission. Check with your local authority first.

Rules vary by country and municipality, and in apartment buildings the housing association must usually approve.

Common pitfalls

Counting floor area with too little head height – it is rarely usable.

Forgetting joist reinforcement and the staircase in the budget.

Missing that dormers need permission. Keep a 10–15% contingency for surprises.

Estimate your attic

In our calculator, choose renovation, tick "Attic conversion" and enter the area. You get an estimate in your currency with VAT shown separately and a PDF report.