CSLB General Building (B)Finishes and Building EnvelopeHard
A roofer is installing step flashing along a sidewall intersection where the composition shingle exposure is 6 inches. Code requires each step flashing piece to overlap the piece below it by a minimum of 2 inches. What is the minimum overall length of each step flashing piece measured along the roof slope?
- A10 inches
- B8 inches
- C6 inches
- D4 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 8 inches
Each step flashing piece must span the full shingle exposure plus the required overlap with the piece below it, so the minimum length equals the 6-inch exposure plus the 2-inch minimum overlap, totaling 8 inches.
Why the other options are wrong
- A. Exceeds the minimum required length calculation.
- C. Covers exposure only, omitting the required overlap.
- D. Too short to cover even the shingle exposure.
Step Flashing Length Sizing
Step flashing pieces at roof-to-wall intersections must be long enough to cover the shingle exposure plus overlap the piece below to prevent water infiltration.
- Minimum overlap between pieces: 2 inches
- Length = shingle exposure + overlap
- Also requires minimum 4-inch height up wall and onto roof
Memory trick: 'Exposure plus overlap equals no leak gap.'