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Carbon monoxide alarm requirements

The rules come from section R315 of the International Residential Code as states and cities adopt it. Below is the wording in published government copies, with the edition each copy states.

Last checked

On this page
  1. Los Angeles County, CA
  2. Connecticut (statewide)
  3. Yakima County, WA
  4. Sources

Carbon monoxide (CO) alarm rules apply to homes with fuel-burning appliances or an attached garage, and say where alarms must go, usually outside sleeping areas. Like smoke alarms, they can be triggered in an existing home when permitted work is done.

Combination smoke and CO alarms can satisfy both rules where the code allows them.

The International Residential Code (IRC) is a model code. It is law only where a state or city adopts it, usually with changes, so the wording below shows how the model reads in published government copies, not the rule where you live.

Los Angeles County, CA

Los Angeles County Residential Code

  • Carbon monoxide alarms shall be installed in the following locations: 1. Outside of each separate sleeping area in the immediate vicinity of the bedrooms. 2. On every occupiable level of a dwelling unit, including basements.1
  • Where a fuel-burning appliance is located within a bedroom or its attached bathroom, a carbon monoxide alarm shall be installed within the bedroom.1

Connecticut (statewide)

2022 CSBC amendments to the 2021 IRC

  • (Amd) R315.3 Location. Carbon monoxide alarms in dwelling units shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms and on each additional habitable level of the dwelling unit.2
  • Where a fuel-burning appliance is located within a bedroom or its attached bathroom, a carbon monoxide alarm shall be installed within the bedroom.2
  • Where alterations, repairs or additions requiring a permit occur, or where one or more sleeping rooms are added or created in existing dwellings, the individual dwelling unit shall be equipped with carbon monoxide alarms located as required for new dwellings.2

Yakima County, WA

2012 IRC, Washington State Amended (2013 handout)

  • R315.1 Carbon monoxide alarms. For new construction, an approved carbon monoxide alarm shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms in dwelling units and on each level of the dwelling and in accordance with the manufacturer’s recommendation.3

Sources

  1. Smoke and Carbon Monoxide Alarms HandoutLos Angeles County Public Works, Building and SafetyChecked November 7, 2026
  2. 2022 Connecticut State Building Code (w/ Errata #1)State of Connecticut, Department of Administrative Services, Office of the State Building InspectorEffective October 1, 2022Checked November 7, 2026
  3. (2012) Smoke Detector & Carbon Monoxide AlarmsYakima County, WA, Public Services, Building & Fire Safety DivisionRevised December 13, 2013Checked November 7, 2026