Effective April 1, 2012, RCW 19.27.530 requires the seller of any owner-occupied single-family residence to equip the residence with carbon monoxide alarms in accordance with the state building code before a buyer or any other person may legally occupy the residence following the sale. This requirement applies to all single family residences, including single family homes, condominiums, and manufactured/mobile homes.

The building code (WAC 51-51-0315) requires that an alarm be installed: (1) outside of each separate sleeping area in the immediate vicinity of each bedroom; (2) on each level of the dwelling; and (3) in accordance with the manufacturer’s recommendations. The building code also requires that single station carbon monoxide alarms comply with UL 2034.  There are no exceptions for properties that do not have fuel-fired appliances or an attached garage. The alarms may be battery operated and can be purchased for as little as $25 from a variety of sources.

In addition, effective April 1st, the building code requires a property owner to install carbon monoxide alarms when alterations, repairs or additions requiring a permit occur, or when one or more sleeping rooms are added or created. There has been a requirement to install carbon monoxide alarms in new construction since January 1, 2011.

Watch this informational video with Annie Fitzsimmons, the Washington Realtor Legal Hotline Attorney about the new law. 

These are some general guidelines for carbon monoxide detectors common to most manufacturers:

• Alarms should be placed on every level of your home, including the basement, and near or over any attached garage.
• They should be located within 10-15 feet outside of each separate sleeping area.
• Detectors can be placed on the wall or the ceiling as specified in the installation instructions.
• Do not install detectors within 15-20 feet of any furnace or fuel burning heat source.
• Detectors should not be placed in or near humid areas, such as bathrooms.
• Place alarms in areas where they will not be damaged by children or pets.
• Do not install alarms in direct sunlight or areas subjected to temperature extremes. (crawlspaces, unfinished attics, porches)
• They should not be installed behind curtains or other obstructions.
• Alarms may not function as designed if installed near ceiling fans, heat vents, air conditioners, fresh air returns, or open windows.
• Life expectancy for detectors will be specific to each manufacturer’s recommendations. Carbon monoxide detectors actually have an expiration date, so check with the manufacturer instructions to determine how long the carbon monoxide detector is supposed to last and maintain your specific unit accordingly.