CSLB C-39 Roofing ContractorLow-Slope RoofingMedium
A building inspector is checking base flashing on a newly installed low-slope modified bitumen roof where it terminates at a parapet wall. Per standard code requirements, what is the minimum height the base flashing must extend above the finished roof surface?
- A6 inches
- B12 inches
- C8 inches
- D4 inches
Show answer & explanationAnswer & explanation
Correct answer: C. 8 inches
Building codes (IBC/CBC) and industry standards require base flashing on low-slope membrane roofs to extend a minimum of 8 inches above the finished roof surface to protect against wind-driven rain and shallow ponding.
Why the other options are wrong
- A. 6 inches is still below the required minimum flashing height.
- B. 12 inches exceeds the minimum code requirement, though sometimes used for extra protection.
- D. 4 inches is insufficient and does not meet minimum code height.
Base Flashing Height Minimum
The minimum vertical height (8 inches) that base flashing must extend above a low-slope roof surface at walls and curbs to prevent water intrusion.
- Applies to walls, curbs, and parapets on low-slope roofs
- 8 inches is the standard code minimum
- Higher flashing may be needed in ponding-prone areas
Memory trick: Flash it up EIGHT to keep water straight.