Preparation

The roofing, shown in Fig. 18, is unrolled and the edges bent up as shown at "b", the bent-up portions being from 1 to 1¾ inches in height. The roof is covered with roofing boards laid tightly together. Felt or sheathing paper is not used, as a rule, under this form of roofing, although the use of these materials tends to preserve the roofing from the injurious effects of gases and moisture in the building. The strips or rolls are cut into proper lengths, as shown at "b" in Fig. 21, and are joined together with one of the following forms of joints.