Twin Falls County, ID Building Safety: Building Permits (2026)

Twin Falls County adopted the 2012 International Building Code, 2012 International Residential Code parts I through IV and IX, the International Energy Conservation Code, International Fire Code, International Mechanical Code, and International Fuel Gas Code as its building regulations under § 7-1-2, with those editions superseded automatically as the Idaho building code board or Idaho HVAC board approve newer versions. Section 7-1-5, Administration, layers the county's own prerequisites on top: an applicant must submit plans and specifications detailed enough to show compliance, plus a completed building and/or HVAC permit application with supporting documentation.

If work starts before a permit is obtained, the county requires a special investigation before it will issue one, and collects an investigation fee equal to the regular permit fee whether or not the permit is ultimately granted. Absent a site-specific engineering evaluation, § 7-1-5(D) sets the county's design criteria: a 30 psf ground snow load, 90 mph three-second-gust wind speed, seismic design category C, severe weathering exposure, 1,500 psf soil bearing pressure, and a 24-inch minimum frost depth. Fees for building permits, HVAC permits, plan reviews, and reinspections are set by the board of county commissioners under § 7-1-6.

Separately, qualifying agricultural buildings on five acres or more, or under 300 square feet on smaller parcels, can skip this standard building permit under Title 7, Chapter 3, but must instead obtain a siting permit under § 7-3A-2, and construction in the unincorporated county also requires its own zoning permit application to the planning and zoning department under § 8-3-4.