Thornton, CO Building Safety: Carbon Monoxide Detectors (2026)

2, enacted as a Thornton-specific addition to the 2024 International Building Code, triggers the carbon monoxide requirement whenever interior work requiring a permit occurs in an existing Group I (institutional) or Group R (residential) occupancy that has an attached garage or contains a fuel-fired appliance such as a furnace or water heater. A combination smoke and carbon monoxide detector may substitute for a separate CO detector as long as its alarm signals clearly distinguish the two hazards, and the device may be hardwired, plugged into an unswitched outlet, or battery powered; unlike smoke alarms, CO detectors under this section are not required to be interconnected.

1 sets the placement standard: detection must sit outside each separate sleeping area within 15 feet of the entrance to each bedroom, and if the carbon monoxide source, such as a furnace or gas fireplace, is located inside a bedroom or its attached bathroom, the detector must be placed inside that room instead. The same 15-foot placement standard carries over to new construction through the city's amended Residential Code, which requires carbon monoxide alarms outside each sleeping area within 15 feet of every bedroom, or inside the bedroom if the fuel-burning appliance sits there.

Compliance is checked by the Thornton Building Official as part of the inspection process tied to the building permit; a job authorized under a permit that triggers this section will not pass final inspection or receive a certificate of occupancy or letter of compliance without the required CO detection in place.