CSLB C-39 Roofing ContractorEstimating and PlanningEasy
A contractor is planning a roofing project for a commercial building with a total roof deck area of 8,500 square feet. The specification calls for a three-ply asphalt and felt built-up roofing system. How many squares of felt underlayment will be needed, assuming no waste factor and standard 36-inch wide rolls?
- A255 squares
- B340 squares
- C85 squares
- D170 squares
Show answer & explanationAnswer & explanation
Correct answer: A. 255 squares
A three-ply system requires three layers of felt. Therefore, the total roof area is multiplied by three to determine the total squares of felt needed.
Why the other options are wrong
- B. This would be for a four-ply system, not a three-ply system.
- C. This only accounts for a single layer of felt, not a three-ply system.
- D. This would be for a two-ply system, not a three-ply system.
Multi-Ply Felt Coverage
The total area of felt underlayment required for a multi-ply built-up roofing system, calculated by multiplying the roof deck area by the number of plies.
- 1 square = 100 square feet
- Each ply adds one layer of felt coverage
- Waste factors are typically added after this calculation
Memory trick: BUR is like a BLT sandwich, layers for strength.