Asphalt Shingle Roofs | Building America Solution Center
Asphalt shingles should only be installed on roof slopes of 2 in 12 or greater. For roof slopes from 2 in 12 up to 4 in 12, double underlayment application is required. Figure 2. Locations of Fasteners for Asphalt Shingles in High-Wind Areas. (Source: FEMA 2019.) Figure 3. Incorrect location of fasteners in an asphalt roof shingle.