Core TradesQuestion 105 of 700
On a low-slope shingle roof, underlayment courses must be lapped so water sheds over each lower course. The MAIN reason for the larger head and side laps on low slopes is:
a.To use more material
b.Slower drainage on low slopes lets water back up, so extra overlap prevents leakage
c.To make the roof heavier
d.To change the roof color
Explanation
Lower slopes drain slowly and water can back up under the covering, so codes require greater head and side laps (and often doubled underlayment) to keep water out. It is not about using more material for its own sake, adding weight, or color.
Law Reference: 2025 CA Building Code, Chapter 15 (Roof Assemblies)Practice all 700 questions free — no signup required.
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