Metal panels go on solid or spaced decks; lapped seams need 3:12 (1/2:12 with sealant) and standing seams 1/4:12; materials and coatings meet the metal tables, with matching fasteners.
Solar shingles and solar roof panels go on solid sheathing at 2:12 or steeper, are listed to UL 7103, wind-rated (A, D or F to 129 mph; F above), and wired per R329 and NFPA 70.
Shingle, tile, metal, slate, wood and solar roofs get labelled underlayment; in normal-wind areas felt, synthetic or self-adhered types qualify, while wind-design areas need the heavier types.
Under shingles, 2:12 to 4:12 roofs get two layers (a half-sheet starter, then sheets lapped half plus 2 in); 4:12 and steeper get one layer lapped 2 in; end laps are 4 in, staggered 6 ft.
In wind-design areas, use two fastened layers, 4 in self-adhered strips over deck joints plus underlayment, or full self-adhered; cap nails go in a 12 in grid with 6 in at laps.
Where ice dams are a known problem, run an ice barrier (two cemented layers or self-adhered) from the eave to 24 in inside the wall line, or 36 in up the slope on 8:12 and steeper roofs.
Local review: San Antonio isn't normally an ice-dam area; check the city's Table R301.2 entry before adding an ice barrier requirement.
Searches all 4,276 IRC 2024 sections, 5,532 IBC 2024 sections and defined terms (Chapters 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 so far) and each city's local rules as they are added. Section numbers and titles from the International Residential Code and International Building Code, 2024 editions, copyrighted by the International Code Council; the IRC's electrical chapters (34 to 43) follow NFPA 70, the National Electrical Code. Requirements are summarized in our words (IRC Chapters 3 to 43, IBC Chapters 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33); read the full text at the link on each result. Local values come from each city's published documents.
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