Smoke/CO Alarms

Buying or Selling a Home?

If you're buying or selling a home in Westford, you'll more than likely need to have your Smoke Alarms and Carbon Monoxide detectors inspected as part of the process.

One issue that we frequently encounter during inspections are residents purchasing alarms and detectors based on recommendations from hardware store/home improvement warehouse employees. While employees may be knowledgeable about the detectors in their stock, they are not always familiar with Massachusetts specific code requirements.

We STRONGLY encourage you to review the following guidelines before purchasing any new alarms and scheduling an inspection with us.

Requirements for Single Family & Two-Family Homes:

  • Smoke alarm and carbon monoxide detector requirements depend on what year your home was constructed, and if there were any major renovations or additions after the initial construction that may have triggered an upgrade 
  • We encourage you to refer to our Smoke Alarm/CO Detector Requirement chart below as a guide to help you make sure your home is properly protected.
  • Also visit the Massachusetts Department of Fire Service and review their information guide on smoke alarm/CO detector requirements when buying/selling a single or two-family home.

Smoke Alarms:

  • All alarms must be Underwriters Laboratory (UL) or Intertek ETL listed
  • "Hardwired" Alarms:
    • The alarm's primary power source is your home's 120v AC electrical system. 
    • If your home is hardwired, you must maintain hardwired smoke alarms. 
    • Hardwired alarms will have a battery back up so the alarm will continue to function if your power goes out.
  • Interconnection:
    • When one alarm in your home activates, all other alarms in the home will sound to alert occupants in an emergency.
    • REQUIRED in all homes built 1975 to present.
    • Hardwired alarms are typically interconnected through your home's wiring. 
    • Wireless interconnection technology is also available.
    • If your home requires hardwired alarms, you may utilize wireless interconnection technology, as long as the primary power source is hardwired to AC power.
  • Battery Operated Alarms
    • Only permitted for use in homes built prior to 1975.
    • The alarm's primary power source is from an internal battery. 
    • All new battery operated alarms installed MUST have a 10 year sealed battery. The 10 year sealed battery eliminates the need to routinely change batteries.
    • Battery operated alarms with wireless interconnection technology is available. 
      • If you are replacing or upgrading battery alarms, replacing them with alarms capable of wireless interconnection is strongly encouraged but not required.
  • Only photoelectric smoke alarms are permitted.
    • Ionization smoke alarms, and dual photoelectric/ionization alarms are available for purchase in stores and online. These types of alarms are not permitted.
  • Smoke alarms must be replaced after 10 years. Manufacturers will typically print a manufacture date on the back side of the detector.
  • Smoke alarms must be installed on ceilings and in accordance with manufacturers instructions.
  • Smoke alarms are not permitted to be installed in attached garages due to risk of false activations.

Heat Detectors:

  • Heat detectors sense rapid rises in temperature that occur in a fire and activate alarm.
  • Heat detectors are required in garages attached to any single family/two family homes built after September 1, 2008.
  • Heat detectors must be hardwired, and interconnected to smoke alarms throughout the rest of the home.
  • Make sure you purchase heat detectors that are compatible with your home's smoke alarms.

Carbon Monoxide (CO) Detectors:

  • One detector must be installed on each habitable level of the home, including basements, and finished attics.
  • Detectors must be installed in hallways OUTSIDE each sleeping area (bedroom). Detectors must be within 10 feet of any bedroom door.
  • Battery operated or plugin style CO detectors are permitted in homes built before September 1, 2008.
  • Hardwired/Interconnected CO detectors are REQUIRED in homes built after September 1, 2008.
  • Combination smoke alarm/carbon monoxide detectors are available. 
    • All combination smoke/CO detectors MUST have tone AND "Voice Alert" feature. This means that when the alarm goes off, the detector will alert occupants whether it's the smoke alarm or carbon monoxide detector that is sounding.
  • Carbon Monoxide Detectors must be replaced every 5-10 years. Manufacture date is typically printed on the back of the detector. Follow manufacturers recommendations.

Smoke Alarm/Carbon Monoxide Detector Resources

Single Family/Two Family Homes