CSLB C-39 Roofing ContractorEstimating and PlanningMedium
A roofer uses 4 nails per shingle and installs 80 shingles per square across a 26-square roof. Nails are sold in boxes of 3,600. How many boxes must be purchased to complete the job?
- A4 boxes
- B5 boxes
- C2 boxes
- D3 boxes
Show answer & explanationAnswer & explanation
Correct answer: D. 3 boxes
Total nails = 4 nails × 80 shingles × 26 squares = 8,320 nails. 8,320 ÷ 3,600 = 2.31, which rounds up to 3 full boxes.
Why the other options are wrong
- A. Over-orders one box beyond actual need.
- B. Significantly exceeds required quantity.
- C. Underestimates total nail requirement.
Fastener Takeoff
Fastener quantities are calculated by multiplying nails per shingle by shingles per square by total squares, then dividing by box quantity.
- Multiply nails/shingle × shingles/square × total squares
- Divide by nails per box to find box count
- Always round up to ensure sufficient supply
Memory trick: Four nails, eighty shingles, multiply it all up.