CSLB C-39 Roofing ContractorEstimating and PlanningMedium
A standing-seam metal roof panel has an overall width of 36 inches but only 34 inches of effective coverage due to seam overlap. The roof width to be covered is 68 feet (816 inches). How many panels are required?
- A26 panels
- B24 panels
- C22 panels
- D28 panels
Show answer & explanationAnswer & explanation
Correct answer: B. 24 panels
Only the effective coverage width counts toward the total, since the overlap portion is not additional coverage. Dividing the total width by the effective coverage: 816 inches ÷ 34 inches per panel = 24 panels exactly.
Why the other options are wrong
- A. Incorrect: overestimates beyond the exact calculation.
- C. Incorrect: understates the panel count needed to fully cover the width.
- D. Incorrect: significantly overestimates panel quantity needed.
Metal Panel Coverage Takeoff
Metal roofing panels are calculated using their effective (net) coverage width, not their overall panel width, because seams overlap adjacent panels.
- Effective coverage width is less than overall panel width due to seam overlap
- Total roof width divided by effective width gives panel count
- Always use net coverage, never overall panel dimension, for takeoff
Memory trick: Overlap eats width, so count only what truly covers.