These should be framed as shown in the section drawing, Fig. 87. An opening of the proper size to receive the dormer should be framed in the roof, as shown in Fig. 77, and the studs of the dormer should be notched out 1 inch over the roof boarding and trimmer rafter and extended to the floor. Notching the studding on to the roof prevents the roof from sagging or breaking away from the sides of the dormer and thus causing a leak, and the studding being extended to the floor also stiffens the trimmer and gives a homogeneous surface to lath on, without-fear of plaster cracks. An enlarged section through the dormer sill is also given in Fig. 87, showing the way in which the flashing should be placed. The flashing should be laid over the upper course of shingles, and a wedge-shaped piece fitted between the sill and flashing and toe-nailed into sill. This keeps the flashing in place and nearly conceals it. The upper end of the flashing should be securely nailed to the back of the sill.
On mansard roofs' the front of the dormer generally comes over the wall, the front studding thus resting on the wall plate; the studding forming the sides may, in this case, be spiked to the top of the trimmer rafters.