Idaho Building Codes

Important: Idaho has extreme variation in ground snow loads due to elevation differences. Valley floors (Boise, Twin Falls, Idaho Falls) typically have ground snow loads of 20-40 psf. Mountain communities (Sun Valley, McCall, Stanley) can have ground snow loads exceeding 100-200 psf. ASCE 7 provides baseline values but many jurisdictions have adopted site-specific snow load maps. Roof slope, exposure, and thermal factors affect the conversion from ground to roof snow load. Reroofing projects must verify the existing structure can support the new roof system weight plus design snow loads. Snow guards and retention systems are commonly required on metal roofs, especially over walkways and entries.

Important: Idaho is one of the most permissive states for contractor regulation. There is no statewide general contractor, roofing, or siding license requirement. Only electrical (Idaho Division of Building Safety), plumbing, and HVAC contractors require state licenses. Individual cities may require business licenses but not trade-specific licenses. Public works projects over $50,000 require a Public Works Contractor License. Idaho does require contractors to register with the Idaho Contractor Registration Board (effective 2023) for projects over $2,000, but this is registration only — no exam, no bond, no insurance requirement.

Important: Idaho has extensive Wildland-Urban Interface (WUI) exposure, particularly in the Boise foothills, Sun Valley/Ketchum area, McCall, and throughout forested mountain communities. Communities in WUI zones often require: Class A fire-rated roofing materials, ember-resistant vents (1/8-inch mesh screening), non-combustible or ignition-resistant exterior materials within defined distances, and defensible space (typically 30-100 feet). The Idaho Department of Lands and local fire districts establish WUI zone boundaries. After significant fire seasons, many communities have enhanced their WUI building requirements.