Smoke & Carbon Monoxide Alarm Requirements

Information from the Massachusetts Division of Fire Safety

There is hard evidence that properly installed smoke and carbon monoxide alarms save lives. Smoke and carbon monoxide detector inspections are required for consumer safety upon the sale or transfer of a property in Massachusetts. Requirements vary depending on the age and residential status of the property. The guidelines that follow are for informational purposes.

A complete guide on Massachusetts Smoke and Carbon Monoxide Requirements is available here.

Note that all detectors should be installed following the manufacturer’s instructions.

Typical One- and Two-family Residences built before January 1, 1975:

  • Smoke detector requirements:
      One on every habitable level of the residence
      On the ceiling at the base of each stairway
      On the ceiling outside of each separate sleeping area
      May be battery powered, hardwired or both
      Detectors within 20 feet of a kitchen or full bathroom must be photoelectric
      Outside of 20 feet of a kitchen or full bathroom, detectors must be either a dual detector (containing both ionization and photoelectric technologies) OR be two separate detectors, one of each technology
      Low voltage household warning systems are exempt from the dual detection requirement
  • Carbon monoxide alarms are required as follows:
      On every level of the residence, including habitable portions of the attic and basement, and within 10 feet of each bedroom door
      Combination detectors (photoelectric smoke and carbon monoxide detector) may be used if within 20 feet of a kitchen or full bathroom
      Combination detectors (ionization smoke and carbon monoxide detector) may be used if outside of 20 feet of a kitchen or full bathroom
      May be either: battery powered, plug-in with battery backup, hardwired with battery backup, or system type



    • Typical One- and Two-family Residences permitted between 1975 and August 27, 1997

  • Smoke Detectors required as follows:
      One on every habitable level of the residence
      On the ceiling at the base of each stairway
      On the ceiling outside of each separate sleeping area
      A minimum of one smoke detector must be installed for every 1200 square feet of living area per level
      Detectors must be hardwired interconnected
  • Carbon monoxide alarms:
      On every level of the residence, including habitable portions of the attic and basement, and within 10 feet of each bedroom door
      Combination detectors (photoelectric smoke and carbon monoxide detector) may be used anywhere
      Combination detectors (ionization smoke and carbon monoxide detector) may be used if the det4ector is outside of 20 feet of a kitchen or full bathroom
      May be either: battery powered, plug-in with battery backup, hardwired with battery backup, or system type


    • Typical One- and Two-family Residences permitted after August 27, 1997

  • Smoke detectors:
      One on every habitable level of the residence
      On at the base of each stairway
      On the ceiling outside of each separate sleeping area
      One smoke detector inside every bedroom
      A minimum of one smoke detector must be installed for every 1200 square feet of living area per level
      Must be hardwired and interconnected smoke detectors with battery backup
      If the smoke detector in within 20 feet of a kitchen or full bathroom, the smoke detector is required to be a photoelectric detector
  • Carbon Monoxide alarms:
      On every level of the residence, including habitable portions of the attic and basement, and within 10 feet of each bedroom door
      Combination detectors (photoelectric smoke and carbon monoxide detector) may be used anywhere
      Combination detectors (ionization smoke and carbon monoxide detector) may be used if the det4ector is outside of 20 feet of a kitchen or full bathroom
      May be either: battery powered, plug-in with battery backup, hardwired with battery backup, or system type



    • Typical One- and Two-family Residences permitted on or after January 1, 2008:

  • Smoke detectors required as follows:
      One on every habitable level of the residence
      On at the base of each stairway
      On the ceiling outside of each separate sleeping area
      One smoke detector inside every bedroom
      A minimum of one smoke detector must be installed for every 1200 square feet of living area per level
      Must be hardwired and interconnected smoke detectors with battery backup
      If the smoke detector in within 20 feet of a kitchen or full bathroom, the smoke detector is required to be a photoelectric detector
      If the smoke detector is outside of 20 feet of a kitchen or full bathroom, the detector is required to be either a photoelectric detector or a dual detector (containing both ionization and photoelectric technologies)
  • Carbon Monoxide alarm requirements:
      On every level of the residence, including habitable portions of the attic and basement, and within 10 feet of each bedroom door
      Combination detectors (photoelectric smoke and carbon monoxide detector) may be used
      Must be hardwired and interconnected with battery backup (may be separate from existing
      smoke detection system)