Bannock County, ID Building Safety: Carbon Monoxide Detectors (2026)

Bannock County's building code adopts the 2018 IRC, whose Section R315 requires carbon monoxide alarms in dwellings with fuel-fired appliances or attached garages and, at Section R315.2.2, sets out when an alteration, repair or addition to an existing home triggers a CO alarm retrofit. Rather than keep the IRC's stock exceptions, the county deleted them at Section 15.04.200 and substituted its own two exceptions specific to Section R315.2.2. Work on a dwelling's exterior surfaces, replacing roofing or siding, adding or replacing windows or doors, adding a porch or deck, or pulling an electrical permit, is exempt from triggering the CO alarm retrofit.

The county also exempts installation, alteration or repair of noncombustion plumbing or mechanical systems, wording that is narrower than the smoke alarm exception at Section R314.2.2, which exempts plumbing or mechanical work generally rather than only noncombustion systems. A combustion-appliance mechanical repair, such as work on a fuel-fired furnace or water heater, is therefore not automatically exempt under Section R315.2.2 and can trigger the CO alarm retrofit even where an equivalent smoke alarm exception would apply. Planning and Development Services determines at permit review which exception, if any, applies to the scope of work, and inspectors verify carbon monoxide alarm placement before a certificate of occupancy is issued.