Dormers

A dormer is a window that is set vertically on a sloping roof. The dormer, in turn, has its own roof, which may be flat, arched, or pointed. Dormers are used, either in original construction or as later additions, to create usable space just under the roof of a building by adding headroom and usually also by enabling addition of windows. Often conflated with the term 'dormer', a dormer window is a window set into the dormer.

Like skylights, dormers provide a dark space with light and, if they open, also ventilation. Unlike skylights, which are flush with the roof surface, dormers increase the amount of headroom in the room and allow for more usable space.

Dormers make it possible to create a romantic and cozy feel for the top floor of a home because the roof slopes down in a way that it seems to embrace the inhabitants of the structure while in addition to light and air, the dormers provide a lofty view of the home’s surroundings.

Dormers are very common in the United Kingdom, where requirements for supplementary space cannot be met by a typical addition in such structures as connected row houses. This has created a boom in the business of extending dormers, a tricky way to add floor space because the dormer cannot be extended beyond the main roof line.