Core TradesQuestion 45 of 700
For asphalt shingles installed on slopes between 2:12 and 4:12, the underlayment must be applied as:
a.A single layer, same as steeper slopes
b.Two layers (doubled) for added protection
c.No underlayment is needed at this slope
d.A continuous membrane only, without shingles
Explanation
Low-to-moderate slopes between 2:12 and 4:12 require doubled underlayment because water drains more slowly and is more likely to back up under the shingles. A single layer applies only to steeper slopes, and omitting underlayment is never allowed.
Law Reference: 2025 CA Residential Code (CRC) R905.2 (Asphalt Shingles)Practice all 700 questions free — no signup required.
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