Roof System Installation Knowledge and Performance
This domain tests whether a foreman can turn drawings and manufacturer instructions into a watertight, code-compliant assembly, and can catch the errors that cause callbacks. Questions cover slope limits, underlayment, fastening, flashing sequence, and ventilation math.
Slope, deck, and underlayment
Steep-slope starts at 4:12. Most asphalt shingles are limited to 2:12, and below 2:12 you need a membrane. Deck panels must be sound, dry, and gapped about 1/8 in. Underlayment laps 2 in. horizontally and 4 in. vertically, upper lap over lower. In cold climates, self-adhering ice barrier runs along eaves to at least 24 in. inside the warm wall line.
Fastening and exposure
Nails sit 1 in. above the exposure line and at least 3/8 in. from the shingle edge, driven flush - never overdriven or angled. High-wind areas require six nails per shingle instead of four. Use hot-dip galvanized or stainless fasteners near the coast. Extra exposure beyond the manufacturer's spec voids the warranty and lifts shingles in wind.
Flashing and ventilation
Layer flashing so each piece sheds onto the one below: underlayment, base flashing, counterflashing. Step flashing at sidewalls interleaves with each shingle course. Provide 1 sq ft of net free vent area per 150 sq ft of attic floor, or 1/300 where a vapor retarder is installed and intake and exhaust are balanced.
Worked example
A 30 ft x 40 ft attic needs ventilation. Area = 1,200 sq ft. At 1/150, required net free area = 1,200 / 150 = 8 sq ft. Split 50/50 between soffit and ridge: 4 sq ft each. A soffit vent rated 0.5 sq ft net free area means 4 / 0.5 = 8 soffit vents, matched by 4 sq ft of ridge vent. Using 1/300 by mistake would halve the vents and leave the attic under-ventilated.
Traps
Mixing up gross and net free area; nailing through the exposure line; skipping ice barrier because the eave looks fine; relying on caulk instead of proper counterflashing; and counting ridge vent alone with no intake path.