CSLB C-39 Roofing ContractorEstimating and PlanningMedium
A roof has 14 plumbing vent stack penetrations requiring pipe flashing boots. The estimator adds 10% extra to cover potential damage during installation, and boots are sold in packs of 6. How many packs must be purchased?
- A5 packs
- B4 packs
- C2 packs
- D3 packs
Show answer & explanationAnswer & explanation
Correct answer: D. 3 packs
Add 10% to the 14 penetrations: 14 × 1.10 = 15.4, rounded up to 16 boots needed. Divide by pack size: 16 ÷ 6 = 2.67, rounded up to 3 packs since partial packs cannot be purchased.
Why the other options are wrong
- A. Far exceeds the actual requirement.
- B. Overestimates by rounding up too aggressively before pack division.
- C. This only covers the base 14 boots without extra, and even then falls short of a full pack count.
Pipe Boot Takeoff
Pipe flashing boot quantities are calculated by counting penetrations, adding a waste/spare allowance, then dividing by the pack size sold.
- Add a spare percentage before dividing by pack size.
- Always round up both the boot count and the pack count.
- Pack sizes vary by manufacturer, commonly sold in sets of 6.
Memory trick: Count penetrations, pad for spares, then pack it up.