Most people know that carbon monoxide alarms are important and save lives, but many are confused about where they should be installed. It can be tricky, since the manufacturer’s recommendations, state, and local requirements often don’t agree. The advice given here is based upon the California Residential Code (CRC).

Required Locations
Since 2011, the State of California has required carbon monoxide alarms in all homes and dwelling units (with gas fired appliances or attached garages). Section R315 of the CRC requires carbon monoxide alarms:

  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.
  3. In each bedroom where a fuel-burning appliance is located inside (or its attached bathroom)

While the above locations are the minimum required, you can always add them in more locations if you like. Since the risk of death from carbon monoxide poisoning is greatest while you are sleeping, adding additional carbon monoxide alarms in bedrooms is recommended.

Immediate Vicinity
While the code require alarms “outside of each sleeping area in the immediate vicinity of the bedrooms” – the question becomes: what is the immediate vicinity? No definition is given, so you’ll have to use your best judgement. If the sleeping areas are really far apart, or if there is a door that separates the sleeping areas, it’s best to have multiple alarms.

Locations to Avoid
A stand alone carbon monoxide alarm can be a plug-in or battery unit place on the wall or ceiling. The manufacturer will provide instructions for placement, but here are some locations to avoid:

  • When wall mounting, place out of reach of children. Under no circumstances should children be allowed to handle the CO alarm.
  • Do not install in kitchens, garages or furnace rooms that may expose the sensor to substances that could damage or contaminate it.
  • Do not install in areas where the temperature is colder than 40°F or hotter than 100°F.
  • Do not install within 5 ft. of heating or cooking appliances.
  • Do not install near vents, flues, chimneys or any forced/unforced air ventilation openings.
  • Do not install near ceiling fans, doors, windows or areas directly exposed to the weather.
  • Do not install in dead air spaces, such as peaks of vaulted ceilings or gabled roofs, where CO may not reach the sensor in time to provide early warning.
  • Do not obstruct the vents located on the alarm. Do not place the alarm where drapes, furniture or other objects block the flow of air to the vents.