CSLB C-39 Roofing ContractorSteep-Slope RoofingEasy
A roofing contractor is inspecting a low-slope commercial building for a new roofing installation. The building is located in an area with moderate wind uplift requirements. Which type of asphalt shingle is generally not recommended for roofs with slopes less than 2:12?
- AArchitectural laminates
- BSelf-sealing three-tabs
- CModified bitumen rolls
- DStrip shingles
Show answer & explanationAnswer & explanation
Correct answer: D. Strip shingles
Strip shingles, particularly three-tab shingles, are generally not recommended for very low-slope applications due to their susceptibility to wind uplift and water infiltration at lower pitches. They rely heavily on gravity and shingle overlap for water shedding.
Why the other options are wrong
- A. Architectural laminates offer better wind resistance and sealing compared to strip shingles, making them suitable for a wider range of slopes.
- B. Self-sealing three-tabs are a type of strip shingle and, despite their self-sealing feature, are still not recommended for slopes below 2:12.
- C. Modified bitumen rolls are specifically designed for low-slope and flat roofs, offering excellent waterproofing and durability.
Asphalt Shingle Slope Limits
Different types of asphalt shingles have minimum slope requirements to ensure proper water shedding and performance.
- Strip shingles typically require a minimum 2:12 slope.
- Architectural shingles can often be used on slopes as low as 2:12 with proper underlayment.
- Low-slope roofing materials like modified bitumen are used for very low slopes (e.g., 0.25:12 to 2:12).
Memory trick: Slope's low, so shingle's slow, pick a roll for where water flows.