CSLB C-39 Roofing ContractorLow-Slope RoofingHard
A 4-ply BUR system uses 36-inch-wide roofing felt applied by the shingle method with each ply overlapping the previous ply by 75 percent (typical for a 4-ply system). What is the exposed width of each felt ply per course?
- A18 inches
- B27 inches
- C4.5 inches
- D9 inches
Show answer & explanationAnswer & explanation
Correct answer: D. 9 inches
For shingle-style BUR application, exposure per ply equals felt width divided by the number of plies: 36 in ÷ 4 plies = 9 inches. This exposure produces the required 75% headlap so that four plies of coverage exist at any point on the roof.
Why the other options are wrong
- A. This doubles the correct exposure and would leave only 2 plies of coverage at some points.
- B. This exposure is far too wide and would not achieve 4-ply coverage.
- C. This halves the correct exposure, which would create too many plies of coverage.
BUR Shingle-Method Exposure
In shingle-style BUR application, felt exposure equals the roll width divided by the number of plies, ensuring consistent multi-ply coverage across the roof.
- Exposure (in) = felt width ÷ number of plies
- 4-ply system with 36-in felt yields 9-in exposure
- Proper headlap ensures full-thickness waterproofing
Memory trick: Divide the width by the plies to find what shows.