Dormer permit: what is allowed without one?

Dormer permit: the main rule

The national rules distinguish between the rear roof slope and the roof slopes facing the street. At the rear, a dormer within certain dimensions is generally permit-free. At the front, the municipality decides, and an environmental permit is usually required there.

In the environmental plan, the municipality can set extra requirements for the appearance, for example the colour, the materials or the position on the roof. That way a street of identical houses stays a calm whole.

When is a dormer allowed without a permit?

There are conditions on the distance to the ridge, the eaves and the sides of the roof, and on the height of the dormer itself. Those dimensions differ per situation. Check the Omgevingsloket to see what applies to your address.

A corner house often has a side wall that is visible from the public road. A roof slope that you see as the back may then count differently under the rules. A dormer on an outbuilding, such as a garage, also has its own rules. If in doubt, contact the municipality.

• On the rear roof slope, not facing the street
• Within the maximum height and distances to ridge and edges
• Not a listed building and not in a protected townscape
• The environmental plan sets no other requirements

Building rules apply even without a permit

Permit-free does not mean rule-free. The dormer must meet the technical building rules: a sound structure, enough insulation and a watertight connection to the roof. That is where the craftsmanship lies, because you only notice a leaking connection when the ceiling below starts to stain.

Also good to know: a dormer on the street side of a terrace sometimes only fits if it matches what the neighbours already have. A good conversation with the municipality beforehand saves time.

If you are placing the dormer in a terrace, also have a word with the neighbours. The work takes place at height and often from scaffolding that may partly stand in front of their house. A short schedule and a fixed point of contact make it easier for everyone.

Also look at what happens inside. A dormer makes the attic higher and lighter, but the existing roof insulation must connect neatly to the new walls. If that is done carelessly, a cold corner forms where condensation can occur. The carpentry inside is therefore just as important as outside.

• Sturdy structure on the existing rafters or purlins
• Insulation of the dormer's walls and roof
• Watertight flashing in lead or a synthetic alternative
• Adequate ventilation in the room behind

A dormer with Daal Constructions

We do the carpentry for dormers in Zwolle and the surrounding area, from opening up the roof to the finishing inside. Shahiro looks at the permit and the right size in advance. During the work the roof stays open for as short a time as possible and is made watertight every day. Read more under dormer carpentry or see the costs of a dormer.

Will the attic become a proper room afterwards? Then new walls and an insulated ceiling often come into play too. For general permit rules, see permit-free building. If you want to insulate the attic at the same time, read what the ISDE subsidy can mean for roof insulation.

Frequently asked questions