Interior Code Requirements in Idaho

Ground snow loads range from 20 psf in the Snake River Plain (Boise, Twin Falls) to 30 psf in the eastern valleys. Statewide base zone — see Mountain Snow Load overlay for panhandle and central mountain counties with loads of 40-80+ psf. Idaho's dramatic elevation changes create highly variable snow loads even within a single county.

Mountain areas with avalanche risk, particularly in resort communities (Sun Valley, McCall, Stanley) and backcountry areas. Structural design must account for avalanche loading where applicable.

Ice barrier required throughout Idaho (Climate Zones 5B, 6B, 7) per IRC R905.1.2 where local jurisdictions have adopted codes. Must extend minimum 24 inches inside exterior wall line.

Historic districts and properties throughout Idaho, particularly Wallace (entire downtown), Boise North End, Idaho City. SHPO review for state/federal involvement.

FEMA-designated flood zones along rivers (Snake, Boise, Payette, Salmon) and lakes. Local floodplain permits required in addition to building permits where codes adopted.

High seismic risk areas, particularly Teton Valley (near Yellowstone), eastern Snake River Plain, and parts of eastern Idaho. Enhanced structural requirements apply.

Extensive WUI areas throughout Idaho, particularly North Idaho panhandle, Boise Foothills, and mountain communities. Class A fire-rated roofing strongly recommended or required by local ordinances.