Page 149 - 2018 National Home Improvement

2018 National Home Improvement Estimator, All Rights Reserved Page 124

Thickness Slope less (1) Slope 4 in
Length (green) than 4 in 12 12 or over
16" 5 butts in 2" 3-3/4" 5"
18" 5 butts in 2-1/4" 4-1/4" 5-1/2"
24" 4 butts in 2" 5-3/4" 7-1/2"
(1) Minimum slope for main roofs -- 4 in 12.
Minimum slopes for porch roofs -- 3 in 12.
Recommended exposure for wood shingles
Figure 7-2

Follow the standards illustrated in Figure 7-3 when you apply wood shingles:

1. Extend the shingles 1-1/2" to 2" beyond the eave line and about 3/4" beyond the rake (gable) edge.

2. Nail each shingle with two rust-resistant nails spaced about 3/4" from the edge and 1-1/2" above
the butt line of the next course. Use 3d nails for 16" and 18" shingles and 4d nails for 24" shingles. If
you’re applying new shingles over old wood shingles, you’ll need longer nails to penetrate through the
old roofing and into the sheathing. Use ring-shank (threaded) nails on plywood roof sheathing that’s less
than 1/2" thick.

3. Allow a 1/8" to 1/4" expansion space between shingles. Stagger the joints in succeeding courses
so the joint in one course isn’t in line with either of the two courses above.

4. Shingle away from valleys, using the widest shingles in the valleys. The valley should be 4" wide at
the top and increase in width at the rate of 1/8" per foot from the top to the bottom. Valley flashing with
a standing seam (W valley) works best. Don’t nail shingles through the metal. Valley flashing should be
a minimum of 24" wide for roof slopes under 4 in 12; 18" wide for roof slopes of 4 in 12 to 7 in 12; and
12" wide for roof slopes of 7 in 12 and over.

5. Place metal edging along the gable end to direct water away from the end walls.

You can use the same instructions for applying wood shakes, except you’ll need longer nails because
shakes are thicker. Shakes are also longer and the exposure distances can be greater: 8" for 18"
shakes, 10" for 24" shakes, and 13" for 32" shakes. For a rustic appearance, lay the butts unevenly.

Install an 18"-wide strip of 30-pound asphalt felt between each course to protect against wind-driven
snow. The lower edge of the shake felt should be above the butt end by twice the exposure distance. If
the exposure distance is less than one-third the total length, most shingle roofers don’t bother with
shake felt.

Asphalt-Fiberglass (Composition) Shingles
Asphalt shingles are made from a fiberglass mat saturated with asphalt. Fiberglass adds strength and
durability, and asphalt adds moisture protection. But asphalt doesn’t bind very well with fiberglass, so
mineral fibers are added to the fiberglass before coating. The result is a "composition" shingle that is
both durable and effective.

The most common type of asphalt shingle is the square-butt strip shingle. It measures 12" by 36", has
three tabs, and is usually laid with 5" exposed to the weather. Top-quality laminated asphalt shingles
weigh as much as 450 pounds per 100 square feet (a square) and can be expected to last up to 45
years. Heavyweight laminated asphalt shingles are sold in four bundles to the square. Regular weight
asphalt shingles are sold in three bundles to the square. Store the bundles flat so the strips don’t curl
when they’re installed. Avoid storing them in the sun, which will activate the self-sealing tabs, causing
the top shingles in each bundle to stick together.