For roof slopes 4:12 or greater, which underlayment is specified for asphalt shingles?

For roof slopes 4:12 or greater, which underlayment is specified for asphalt shingles?

• A. One layer #15 non-perforated felt
• B. Two layers of felt
• C. No underlayment
• D. One layer #30 felt

Answer: (A)

The correct choice specifies that for roof slopes of 4:12 or greater, one layer of #15 non-perforated felt is recommended as an underlayment for asphalt shingles. This is in accordance with standard roofing practices and building codes which aim to ensure sufficient protection against moisture intrusion while maintaining proper ventilation and breathability within the roofing system. Using one layer of #15 non-perforated felt helps to create a barrier that can resist water penetration during rain events, particularly in regions subject to wind-driven rain. This thickness of felt is adequate for slopes 4:12 and above, as the pitch of the roof allows for water runoff to occur effectively, reducing the potential for pooling or leaks. The other choices either suggest an unnecessary addition of layers or lack of protective material entirely, which would not provide adequate weatherproofing for asphalt shingles in most roofing contexts. Thus, the selection of one layer of #15 felt balances performance and cost while adhering to recommended building practices.

The correct choice specifies that for roof slopes of 4:12 or greater, one layer of #15 non-perforated felt is recommended as an underlayment for asphalt shingles. This is in accordance with standard roofing practices and building codes which aim to ensure sufficient protection against moisture intrusion while maintaining proper ventilation and breathability within the roofing system.

Using one layer of #15 non-perforated felt helps to create a barrier that can resist water penetration during rain events, particularly in regions subject to wind-driven rain. This thickness of felt is adequate for slopes 4:12 and above, as the pitch of the roof allows for water runoff to occur effectively, reducing the potential for pooling or leaks.

The other choices either suggest an unnecessary addition of layers or lack of protective material entirely, which would not provide adequate weatherproofing for asphalt shingles in most roofing contexts. Thus, the selection of one layer of #15 felt balances performance and cost while adhering to recommended building practices.