Smoke Alarms | CRC § R314


Smoke alarms are critical safety devices that detect the presence of smoke, alerting occupants to potential fires. Understanding the code requirements for smoke alarms can help ensure the safety of your home and family.

To assist in your comprehension of the code sections provided, let's decipher some key terms and ideas:

  1. Smoke Alarm: A device that sounds an alert when smoke is detected, indicative of a potential fire.
  2. UL 217: Underwriters Laboratories (UL) is an organization that sets safety standards for various products. UL 217 is the specific standard for smoke alarms, ensuring they meet certain safety and performance requirements.
  3. UL 2034: This is another UL standard, but it pertains to carbon monoxide alarms. Some alarms can detect both smoke and carbon monoxide, and such combination devices must meet both UL 217 and UL 2034.
  4. Interconnection: This refers to the practice of connecting multiple alarms in such a way that if one alarm is triggered, all alarms within the dwelling will sound. This is especially important in larger homes to ensure that an alarm is heard throughout the property.
  5. Ionization Smoke Alarms: These are a type of smoke detector that uses a small amount of radioactive material to ionize air in an internal sensing chamber, thus detecting smoke. These alarms are generally more responsive to flaming fires.
  6. Photoelectric Smoke Alarms: These alarms use a light beam and light sensor to detect smoke. When smoke particles obstruct the light beam, the change in light intensity is detected by the sensor, which triggers the alarm. These alarms are generally more responsive to fires that begin with a long period of smoldering.

The sections of the CRC you'll be reading address rules on the installation and maintenance of smoke alarms in residential dwellings. These guidelines are important to understand whether you're constructing a new home, making alterations to an existing home, or simply want to ensure your current home is as safe as possible.


The requirements for smoke alarms are outlined in CRC R314 and are required to be installed with new construction of dwellings. Where dwelling alterations, repairs or additions requiring a permit occur, the individual dwelling unit shall be equipped with smoke alarms.


Smoke alarms shall be listed in accordance with UL 217. Combination smoke and carbon monoxide alarms shall be listed in accordance with UL 217 and UL 2034.


Some alarms are required in each sleeping room, outside each separate sleeping area in the immediate vicinity of the bedrooms, in each additional story of the dwelling (including basements and habitable attics), and in the room open to the hallway serving bedrooms if the ceiling height of that room exceeds that of the hallway by 24”. Additionally, the installation of smoke alarms and smoke detectors shall comply with the location requirements CRC R314.3.3. Some of these additional requirements are listed below.

  1. Garages. Smoke alarms and smoke detectors shall not be located within unfinished attics or garages or in other spaces where temperatures can fall below 40°F (4°C) or exceed 100°F (38°C). Heat alarms can be used as an alternative.
  2. Near Bathrooms. Smoke alarms shall be installed not less than a 3 foot (0.91 m) horizontal distance from the door or opening of a bathroom that contains a bathtub or shower unless this would prevent placement of a smoke alarm required by other sections of the code.
  3. Near Cooking Appliances. Smoke alarms or smoke detectors shall be installed a minimum of 20 feet horizontal distance from a permanently installed cooking appliance. Ionization smoke alarms with an alarm-silencing switch or photoelectric smoke alarms shall be permitted to be installed 10 feet (3 m) or greater from a permanently installed cooking appliance.
  4. Near Heating/Cooling Registers. Smoke alarms and smoke detectors shall not be installed within a 36 in. (910 mm) horizontal path from the supply registers of a forced air heating or cooling system and shall be installed outside of the direct airflow from those registers.
  5. Near Ceiling Fans. Smoke alarms and smoke detectors shall not be installed within a 36 in. (910 mm) horizontal path from the tip of the blade of a ceiling-suspended (paddle) fan.
  6. Near Stairs. Where stairs lead to other occupied levels, a smoke alarm or smoke detector shall be located so that smoke rising in the stairway cannot be prevented from reaching the smoke alarm or smoke detector by an intervening door or obstruction.


For new construction of dwellings, the smoke alarms shall be interconnected in such a manner that the activation of one alarm will activate all the alarms in the individual unit. For alterations to existing dwellings, interconnection of alarms is not required.