Dormer window

A dormer is a small roofed structure that projects outwards from the main pitched roof of a building. Dormers can be included in the original construction of a building or added on subsequently.

Dormers are becoming more common in homes as they can help create extra headroom in spaces that may otherwise be too small or too low for habitation. They enable the creation of rooms in the roof or loft without needing to construct a new storey. Dormers will typically have dormer windows set into them to allow light and ventilation.

There are a number of different types of dormers including:

Box roof/flat roof: The plane of the roof is horizontal. This type of dormer provides the most space and floor area inside the building.

Gable: These have a gable roof, with the front of the dormer being flat with a pitched roof and vertical sides.

Hip roof: The roof comprises of three sloping panels that meet at the ridge.

Arched/eyebrow: This is similar to the hipped dormer but has an arch or curve which allows it to blend in to the existing roof.

The insertion of dormer windows as part of a loft conversion does not normally require planning permission. However, If the roof space is altered or extended and it exceeds specified limits and conditions, permission may be necessary. It may also be necessary to obtain permission within conservation areas, National Parks, Areas of Outstanding Natural Beauty or the Broads, or if the building is listed.

Dormer windows may require building regulations approval.

[edit] Related articles on Designing Buildings Wiki.

• Clerestory.
• Domestic roof.
• Domestic windows.
• Loft conversion.
• Mansard roof.
• Velux window.
• Window.