CSLB C-39 Roofing ContractorFlashing, Ventilation and InsulationMedium
A mason is coordinating with a roofer to install counter flashing into a raked mortar joint on a brick chimney. What is the typical minimum embedment depth required into the mortar joint for the counter flashing to be considered properly secured?
- A1 inch
- B0.5 inch
- C1.5 inches
- D3 inches
Show answer & explanationAnswer & explanation
Correct answer: C. 1.5 inches
Standard practice and manufacturer/code guidance calls for counter flashing to be embedded a minimum of 1.5 inches into a raked-out mortar joint, then sealed, so it stays anchored and watertight over time.
Why the other options are wrong
- A. Still less than the accepted minimum embedment.
- B. Too shallow; flashing could work loose over time.
- D. Excessive and not typically required or practical.
Counter Flashing Embedment
Counter flashing set into masonry should be embedded at least 1.5 inches into a raked mortar joint and sealed to prevent water entry and flashing displacement.
- Works with base/step flashing to shed water over the roof-to-wall joint.
- Mortar joint is raked out, flashing inserted, then re-pointed or caulked.
- Reglet method is an alternative embedment technique.
Memory trick: 'One and a half keeps the flashing safe.'