CSLB C-39 Roofing ContractorSteep-Slope RoofingHard
A roofing inspector is examining a newly installed slate roof. To ensure proper installation and longevity, what is the minimum acceptable side lap for individual slate tiles, regardless of the roof's slope?
- A1 inch
- B3 inches
- C4 inches
- D2 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 3 inches
For slate roofing, a minimum side lap of 3 inches is required to prevent water from entering the roof system through the vertical joints. This ensures that the vertical joints of successive courses are adequately covered.
Why the other options are wrong
- A. 1 inch side lap is insufficient for slate and would compromise its watertightness.
- C. 4 inches would be more than sufficient but is not the minimum required for side lap.
- D. 2 inches is also insufficient; slate relies on substantial overlap to shed water effectively.
Slate Roof Side Lap
Side lap in slate roofing refers to the horizontal distance that the edge of one slate overlaps the vertical joint of the slates in the course below it.
- Crucial for preventing water penetration through vertical joints.
- Minimum 3-inch side lap is a universal requirement.
- Ensures adequate coverage over fasteners and joints.
Memory trick: Slate's side, three inches wide, keeps the water outside.