CSLB C-39 Roofing ContractorLow-Slope RoofingHard
A building is located in a high-wind exposure zone requiring enhanced mechanical attachment of a TPO membrane. Field zone fastening is 1 fastener per 2 sq ft, while the corner zone requires 1 fastener per 0.5 sq ft. For a 10 ft x 10 ft corner zone, how many fasteners are required?
- A100 fasteners
- B200 fasteners
- C50 fasteners
- D150 fasteners
Show answer & explanationAnswer & explanation
Correct answer: B. 200 fasteners
The corner zone area is 10 ft x 10 ft = 100 sq ft. At a fastening rate of 1 fastener per 0.5 sq ft, the required number is 100 sq ft ÷ 0.5 sq ft/fastener = 200 fasteners.
Why the other options are wrong
- A. 100 fasteners would apply if using 1 fastener per sq ft, not the enhanced corner rate.
- C. 50 fasteners uses the field zone rate (1 per 2 sq ft), not the corner rate.
- D. 150 fasteners does not correspond to the given corner attachment density.
Wind Uplift Zone Fastening Calculation
High-wind roof designs require enhanced (denser) mechanical fastening in corner and perimeter zones compared to the field, per wind uplift engineering ratings.
- Corner zones experience the highest wind uplift pressures
- Fastener density increases dramatically (denser spacing) in corners
- Calculate fasteners by dividing zone area by required area-per-fastener
Memory trick: Corners catch the worst wind, so pack the fasteners tight.