Which roof slope is required for installation of asphalt strip shingles?

• A. 1:12
• B. 2:12
• C. 3:12
• D. 4:12

Answer: (B)

The installation of asphalt strip shingles typically requires a minimum roof slope of 2:12. This means that for every 12 horizontal inches, the roof should rise at least 2 vertical inches. A slope of 2:12 is considered necessary to ensure proper water drainage and to prevent potential leaks, as it allows rainwater to shed effectively rather than pooling on the roof surface.

Additional slopes, such as 3:12 or 4:12, are also acceptable for asphalt shingles and may enhance performance, but the minimum requirement is established at 2:12. This consideration ensures that the roofing material adheres correctly and functions as intended under various weather conditions.

While a slope of 1:12 might allow for some water drainage, it is generally not adequate for asphalt shingles due to the higher risk of water infiltration and the potential for shingle failure. Thus, the requirement of 2:12 serves as a standard in the roofing industry to support the longevity and effectiveness of the roofing system.