LOW SLOPE ROOF DETAILS

The minimum roof slope on which shakes are recommended is 1:3 and for shingles, 1:4. It is possible, however, to apply shingles or shakes successfully to solid-sheathed roofs of lower slope providing a special method of application is followed (Figure 8.) The prescribed method provides a double roof on which the shingles or shakes are applied to a lattice-like framework embedded in a bituminous surface coating.

A conventional hot-mop ( or suitable roll-type) asphalt roof should be applied over the roof deck. With the final hot-mop application 2"x 4" (50.8 mm x 101.6 mm) spacers of Western Red Cedar or preservative treated lumber are embedded in the bituminous coating. These spaces are installed over the rafters at 24" (609.6 mm) O.C. and extend from eave to ridge.

Next, 1" x 4" (25.4 mm x 101.6 mm) or 1" x 6" (25.4 mm x 152.4 mm) nailing strips, spaced according to the weather exposure selected for the shingles or shakes, should be nailed across the spacers to form a lattice-like nailing base. For example, if 24" (609.6 mm) shakes are to be installed at a weather exposure of 10" (254 mm), the nailing strips would also be spaced at 10" (254 mm) on centers.

Finally, the shingles or shakes are applied in the normal manner with a starter course at the eave and felt interlays between each course of shakes (Figure 8).