Typical dormer framing
Dormers are framed so that the rafters at each side are doubled to support the side studs and valley rafters. The top ends of the valley rafters are supported by a header spanning between the doubled rafters (Figure 88). The most common method of construction is to install the roof sheathing before the dormer is framed, and then cut the sheathing flush with the framing members around the opening. A bottom plate added on top of the sheathing supports the side studs enclosing the dormer and also serves as a nailing base for the wall sheathing.