Page 124 - 2018 National Home Improvement

2018 National Home Improvement Estimator, All Rights Reserved Page 101

Siding shingles can be applied over either wood or plywood sheathing or over existing board siding.
When installed over sheathing, apply 15-pound asphalt felt between the sheathing and the shingles. If
the surface is irregular, apply horizontal furring strips of 1” x 3” lumber or 1” x 4” lumber. Spacing has to
match the exposed shingle length. Use Figure 6-11 to estimate the furring required for various
exposures per 100 square feet of shingle siding. Leave a gap of 1/8” to 1/4” between shingles to allow for
expansion during wet weather.

Shingle Linear Feet per
Exposure 100 SF of Siding
4” exposure 300 feet
4-1/2” exposure 270 feet
5” exposure 240 feet
5-1/2” exposure 220 feet
6” exposure 200 feet
6-1/2” exposure 180 feet
7” exposure 171 feet
8” exposure 150 feet

Linear feet of furring per 100 square feet of shingle siding
Figure 6-11

Single-course shingles are applied like bevel siding. Each top course laps over the course below with all
joints staggered. See Figure 6-12. Use second-grade shingles (rather than first or third grade) because
only one-half or less of the butt portion is exposed.

Compare the double-course shingles in Figure 6-13. The first grade (No. 1) shingles cover the
undercourse (third grade) shingles. The butt ends of top course shingles should project 1/4” to 1/2”
beyond the butt ends of undercourse shingles. With double coursing, shingle exposure of the top course
can be greater. Figure 6-14 shows recommended exposure distances for shingles.