Dormer and Eyebrow Windows

Abstract

Dormer (figure 9.1) and eyebrow (figure 9.2) windows are a means of providing light and ventilation to rooms constructed in the roof space of a dwelling (figure 9.3). It must be remembered that when an attic room is constructed in an existing building the ceiling joists (usually 100 × 50 mm) to the room below will not be strong enough to resist the loads that they will be subjected to when the room is occupied. It is not practical to remove these joists; joists of adequate size must be placed alongside those already there. These will usually be around 200 × 50 mm.