CSLB C-39 Roofing ContractorEstimating and PlanningMedium
A roof requires drip edge along 180 linear feet of eaves and 140 linear feet of rakes, for a combined edge length of 320 feet. Drip edge stock comes in 10-foot pieces, and the estimator adds a standard 5% waste allowance for laps and cuts. How many pieces of drip edge should be ordered?
- A34 pieces
- B32 pieces
- C33 pieces
- D36 pieces
Show answer & explanationAnswer & explanation
Correct answer: A. 34 pieces
Adding 5% waste to 320 feet gives 320 × 1.05 = 336 linear feet. Dividing by the 10-foot piece length gives 336 ÷ 10 = 33.6, which rounds up to 34 whole pieces since partial pieces cannot be ordered.
Why the other options are wrong
- B. Incorrect: this ignores the 5% waste allowance entirely.
- C. Incorrect: rounds down instead of up, leaving insufficient material.
- D. Incorrect: overestimates beyond the calculated waste-adjusted total.
Drip Edge Takeoff
Drip edge quantities are calculated from total eave and rake footage plus a waste allowance, then divided by stock piece length and rounded up.
- Combine eave and rake linear footage
- Apply standard waste percentage (commonly 5%)
- Round the final piece count up to the next whole piece
Memory trick: Edges add up, waste adds more, always round the score.