Residential · IRC 2021 §R905.1.1
Asphalt Shingle Underlayment Application
Underlayment laps to scale: two layers with a 19 in. eave strip on 2:12 to 4:12, one layer lapped 2 in. at 4:12 or more, 4 in. end laps offset 6 ft, and fastener spacing.. Referenced to IRC 2021 §R905.1.1.
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