Carbon monoxide detectors; where required

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Carbon monoxide (CO) is a tasteless, colorless, odorless and poisonous gas produced by burning fossil fuels, such as, natural gas, propane, wood, etc.

Code, local building jurisdictions and manufactures recommended installation requirements generally require the following:

Where do they go?

  • Each level of a home should have a CO alarm. For example, if the home is two-stories, then a minimum of 2 CO alarms/detectors is required, if three-stories, then a minimum of three is required. Also, one should be in the basement if the home has one.
  • One in each bedroom hallway, and generally within 15 feet of all bedroom doors.
  • Hallways – if 40 feet long or longer; two may be required.
  • At least 4 inches from all exterior wall / ceiling corners and at least 3 feet from supply or return vents. (Check manufactures’ recommendations for your particular detector – for it varies from manufacture to manufacture.)
  • They can be put at any height. They do not need to be put on the ceiling. CO detectors may be put low or high on a wall or on the ceiling.  The reason is that carbon monoxide is present at all levels, verses smoke, which rises to the high areas, which is why we put smoke alarms up high. ( note that a few manufactures detectors are not designed to go on ceiling areas – check the installation instructions)

For added protection put one in each bedroom. They are generally not required in each bedroom, but recommend by by the Fire Marshall and the manufacture.

Bedrooms with a firepalce

If a bedroom has a gas or wood burning fireplace, then there should be a carbon monoxide detector in it as well. Even if there is one in the hallway outside of the bedroom. The reason is that even though there is one in the hallway outside the bedroom, should the bedroom door be closed, then the bedroom occupants may be overcome by carbon monoxide from the bedroom fireplace before the hallway alarm goes off.

Do not place:

  • Within 15 feet of heating or cooking appliances
  • Near very humid areas like bathrooms or laundry rooms
  • In kitchen areas
  • In garages

What type can be used?

The carbon monoxide detector can be one of 3 types:

  1. Battery-powered
  2. Plug in type
  3. Hard-wired with a battery backup


  • The carbon monoxide detector must produce a “distinct, audible alarm that clearly differentiates between a carbon monoxide alarm warning and a smoke detector warning”.
  • May use a combined detector as a smoke detector and carbon monoxide detector.
  • Remember: CO alarms should be installed according to the manufacturer’s instructions.
  • In newly built homes they must be hardwired, in older homes plug-ins and battery operated ones are generally acceptable.

Recent remodeling with a permit?

If the value was over $1,000. Then a Carbon Monoxide detector is usually required.

Does Every House Require a Carbon Monoxide Detector?

If the existing home has a fossil fuel burning heater or appliance, a fireplace or an attached garage – then one is required.

Electric homes with no fossil fuel burning devices like, fireplaces, gas stoves, gas ovens, gas laundry dryers or attached garages, then generally CO detectors are not required. Note if there is an attached garage, then one is required.

Know the Symptoms of CO Poisoning

Similar to the flu but without the fever. They include: dizziness, nausea, fatigue, irregular breathing and headache