Twin Falls County, ID Building Safety: Fire Sprinkler Requirements (2026)

Section 7-1-3(C) amends the adopted International Fire Code with two county-specific provisions. First, citing Idaho Code § 41-253(2), a detached single-family dwelling built on five acres or more, outside an incorporated city and not within a designated area of city impact, is exempt entirely from the International Fire Code's water supply and access requirements. Second, in rural areas and small communities of the county, including areas of city impact, the local fire chief or a designee may reduce the fire-flow requirements for an isolated building or group of buildings where meeting the full requirement is impractical.

That reduction can take one or more forms: dividing a building with a two-hour fire barrier to shrink the area below the cubic footage set by NFPA 1142, installing a fire sprinkler system built to NFPA 13, 13-D, or 13-R, or installing a full-coverage, monitored fire detection system. The provision was adopted with the 2015 building codes ordinance, Ordinance 240, and amended by Ordinance 277 in November 2022. In practice, this means Twin Falls County does not mandate residential fire sprinklers across the board; a sprinkler system is one of three options the fire chief may accept as a substitute for full fire-flow infrastructure, and very large rural lots are exempted from the underlying water-supply requirement altogether.