CSLB C-39 Roofing ContractorSteep-Slope RoofingHard
A homeowner wants to install a new slate roof. The chosen slate tiles are 16 inches long, and the roof has a relatively steep pitch of 8:12. To achieve a secure and weather-tight installation, what is the minimum recommended headlap for these slate tiles?
- A3 inches
- B4 inches
- C2 inches
- D5 inches
Show answer & explanationAnswer & explanation
Correct answer: A. 3 inches
For roof pitches of 8:12 and steeper, a minimum headlap of 3 inches is generally sufficient for slate tiles to ensure proper water shedding. While some manufacturers may allow 2 inches on very steep slopes, 3 inches is a safer and more common minimum for this pitch range.
Why the other options are wrong
- B. 4 inches is typically required for moderate slopes (e.g., 6:12 to 8:12) to ensure adequate overlap.
- C. 2 inches is sometimes allowed for very steep slopes (e.g., 12:12 or greater) but 3 inches is more universally recommended for 8:12.
- D. 5 inches would be excessive for an 8:12 pitch and is reserved for lower slopes or specific conditions.
Slate Roof Headlap
Headlap for slate roofing is the vertical distance that the top of a slate overlaps the head of the slate in the second course below it, crucial for waterproofing.
- Headlap varies significantly with roof pitch.
- Steeper roofs require less headlap.
- Minimum headlap can range from 3 to 4 inches for most applications.
Memory trick: Slate's embrace: the steeper the rise, the smaller the space.