Loft conversion: what does it cost and what else is involved?

What does an attic conversion cost?

These are the typical prices per item for an attic of about 25 m²:

Indicative guide prices, reference date September 2026, taken from public price overviews; not every provider states whether VAT is included. For the renovation of a home over 10 years old, 6% VAT often applies, otherwise 21%. You will hear your exact price after a visit or in your quote, following the free consultation.

The electrics are installed by our own electricians, in the same schedule as the rest of the conversion.

The staircase is the item people forget most often. If there is a loft ladder now, the stair opening has to become larger, and a fixed staircase takes up space on the landing. So first check whether there is room for it.

What needs to happen before an attic becomes a room?

An attic becomes a room when it is warm, light and easy to reach. This happens in the following order, from what will later disappear behind the finishing to what you can see:

Insulation comes before the finishing. If you finish the attic first and insulate the roof from the inside later, you pay twice for the sloping walls.

If you want more standing height, you can have a dormer installed. Whether that needs a permit depends on its dimensions, on whether it is at the front or the back, and on the rules of your region and municipality. So check beforehand with the planning department of your municipality.

What does finishing a converted attic cost?

At Bouwsector België, fleece wall liner with one coat of paint on a sloping attic wall costs €26.49 per m², because we price every sloping attic wall as a ceiling.

An example for an attic of 25 m² with 30 m² of straight wall, such as the gable ends and the knee walls, and 35 m² of sloping roof and ceiling. The measurements are an assumption.

Prices from our 2026/2027 price list, valid from 1 September 2026: fleece wall liner on walls €18.99 per m² (30 to 100 m²), sloping and ceiling €26.49 per m²; plastering €22.99 and €23.99 per m², priming and painting €18.99 and €19.99 per m². Prices exclude VAT.

Fleece wall liner is the fastest route on new plasterboard. There is no drying time for a plaster coat, and we apply, fill and paint a complete home in 3 days. If you choose plastering, allow about 4 weeks of drying according to Knauf before painting.

At 65 m² the job stays above 50 m², so there is no small-job surcharge. If there are already boards against the roof that you want to keep, you can have attic boards painted for €13.99 per m² for one coat.

Do you need a dormer, or are roof windows enough?

Roof windows are enough if you mainly want light and the attic is high enough under the ridge. Two roof windows cost €1,900 to €2,100 installed.

A dormer gives you what roof windows do not: space where you can stand upright, right up to the window. In an attic with a low ridge, that is the difference between a storage space with a bed and a real room. It does cost €9,500 to €10,500 more than roof windows.

If you are unsure, measure the part of the floor where you can stand upright. If a bed, a wardrobe and a walkway fit there, roof windows are often enough. If not, the dormer is no luxury.

How do you have your attic converted by us?

Request a quote or call us on weekdays between 9:00 and 17:00. Send the dimensions of the attic, a photo of the roof and the stairs, and what you want to use it for: a bedroom, a workspace, two rooms or a bathroom. In a free consultation we discuss the plan, and then you receive a tailored quote.

If you agree, we take measurements and check the walls. The final price and schedule are then fixed, and we start on the day we agree together. You pay 50% on the first working day, once all materials are on site and we have started, and 50% on completion.

The structural work is done by our four in-house contractor teams of four people each, the finishing by our 97 in-house craftspeople: 40 wallpaper hangers, 32 plasterers and 25 painters. If the attic is too low for a room, converting a garage into living space can also provide extra room.

For the whole home we take on the complete renovation as contractor, with a single point of contact. We work throughout Belgium: Flanders, Brussels and Wallonia.