Dormer costs in 2026: what are you paying for?

Dormer costs by width

Width is the most important factor. Every extra metre means more structure, more frame and more roofing. At the same time, fixed items such as opening up the roof, the scaffolding and finishing the junctions with the roof tiles stay roughly the same. A wider dormer is therefore often slightly cheaper per metre.

The indications below assume a dormer with uPVC frames, HR++ double glazing, an insulated flat roof and a finished interior, including VAT.

• Up to 2 metres wide: roughly €7,000 to €10,000
• 2 to 3 metres wide: roughly €9,000 to €13,500
• 3 to 4 metres wide: roughly €12,000 to €18,000
• Wider or with more tilt and turn windows: often extra

Prefab or built on site

A prefab dormer is made in a factory and lifted into place by crane in one day. That is quick, but the dimensions and design are fairly fixed. A dormer built on site adapts to the roof: a different roof pitch, a chimney nearby or an unusual width is then no problem.

Daal Constructions builds dormers as bespoke carpentry. That takes a little longer on the roof, but you decide the size, the finish and the layout of the frames. More about that approach under dormer carpentry. Unsure about the frame material? Read timber or uPVC window frames.

• Prefab: installed quickly, fixed sizes
• Built on site: fits any roof
• Frames in uPVC or timber
• Interior finish matched to the loft

What else comes on top of dormer costs?

At the front of a house a dormer often requires an environmental permit (omgevingsvergunning). At the rear it can be permit free under certain conditions. Always check with the municipality or via the Omgevingsloket; the fees are a separate item. Read more under dormers and permits and building without a permit.

Also: do solar panels need to come off the roof temporarily, do you want to insulate and finish the loft at the same time, or is an extra window needed in the gable? Those items are not always in a standard price. For roof and glass insulation a grant may sometimes apply, see grants for renovation.

• Fees for an environmental permit
• Scaffolding or a cherry picker
• Temporarily removing and refitting solar panels
• Insulating and finishing the loft

Having a dormer built around Zwolle

A dormer turns a dark loft with sloping walls into a proper room with standing height and daylight. In new-build homes we have laid out lofts with a storage loft and two rooms; a dormer gives a lot of extra usable space in that situation. Think in advance about what you want to use the loft for, so that the layout of frames and walls can be matched to it.

Daal Constructions does not quote fixed prices for dormers, because every roof is different. Shahiro Daal comes to have a look, measures up and discusses what is feasible. After that you receive a tailored quote, including the interior finishing if you wish. We work from Zwolle and within a radius of about 40 kilometres.

Frequently asked questions