Wisconsin Carbon Monoxide Alarm Law

All residential structures in the state of Wisconsin are required to have working Carbon Monoxide (CO) Detectors. As of February 1, 2011 every residential structure (new and existing) is required to be compliant with Administrative Codes SPS 321 (PDF) and 328 (PDF) of Wisconsin State Law. This law requires single family, duplexes and multifamily units (apartments/condos) to install and maintain working Carbon Monoxide Detectors.

What You Need to Know

  • All single family and 2-unit homes - new and existing - must install a CO alarm on every floor level, near sleeping areas.
  • New construction must be hard-wired with a battery back-up.
  • Existing homes may install any type of CO alarms; battery, plug-in, or combination smoke/CO devices.
  • A carbon monoxide detector required under this section shall bear an Underwriters Laboratories, Inc., listing mark.
  • The law took effect February 1, 2011.
  • Alarms should be installed in accordance with directions from manufacturer.


  • CO alarms are only required in new and existing homes that have any fuel burning appliance, which includes: stoves, ovens, grills, clothes dryers, furnaces, boilers, water heaters, fireplaces and heaters or an attached garage.
  • Alarms do not need to be installed in the attic, garage or storage area of homes.


  • Test alarms monthly.
  • Replace alarms according to manufacturer instructions.
  • Check batteries and replace twice a year.
  • Alarms should never be disconnected or unplugged.
  • Batteries should never be removed for other uses.


If you have any questions regarding compliance, please contact 1 of our fire inspectors at 608-837-5066 and they will gladly assist you.