Where a shingle roof runs up beside a vertical sidewall, the correct flashing is:
- one continuous L-shaped strip under all courses
- a bead of sealant along the wall joint
- roll roofing turned up the wall 2 in.
- step flashing, one piece with each course
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D. step flashing, one piece with each course
Individual step flashings are interleaved with every shingle course so each piece laps the one below and water is stepped back out onto the shingles. A single continuous strip lets water that gets behind it run all the way down under the shingles.
Reference: IRC 2021 R905.2.8.3
Which modified bitumen sheet is modified with a plastic and is most commonly installed by torch?
- SBS modified bitumen
- EPDM membrane
- Type IV ply sheet
- APP modified bitumen
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D. APP modified bitumen
APP (atactic polypropylene) gives the bitumen plastic-like properties and a higher softening point suited to torch application. SBS is rubber-modified and is usually mopped, set in cold adhesive, self-adhered, or torched only when made for it.
Reference: NRCA Roofing Manual: Membrane Roof Systems
A gable roof has two identical rectangular planes. Each plane is 40 ft long at the eave and measures 16 ft from eave to ridge along the slope. What is the total roof area in squares?
Answer in squares.
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12.8 squares
Area of one plane = 40 x 16 = 640 sq ft. Two planes = 1,280 sq ft. 1,280 / 100 = 12.8 squares.
Reference: Roofing estimating: area of rectangular roof planes
OSHA allows a safety monitoring system to be used alone, with no other fall protection, for roofing work on a low-slope roof that is no more than:
- 25 ft wide
- 100 ft wide
- 50 ft above the ground
- 50 ft wide
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D. 50 ft wide
On low-slope roofs 50 ft or less in width a safety monitoring system by itself is permitted. Wider roofs need a warning line combined with the monitor, or guardrails, nets or personal fall arrest.
Reference: OSHA 29 CFR 1926.501(b)(10)
Asphalt shingles are being installed on a 3:12 roof under the IRC. Compared with a 6:12 roof, what must change?
- Underlayment goes on in two layers
- Shingle exposure is cut in half
- Shingles are fully bedded in cement
- Six nails are used in each shingle
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A. Underlayment goes on in two layers
Between 2:12 and 4:12 water drains slowly and can back up under the tabs, so the code calls for a doubled underlayment. Extra nails address wind, not slow drainage, and the exposure does not change.
Reference: IRC 2021 R905.1.1 and R905.2.2