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Smoke Detector Requirements

Dwelling units, congregate residences, hotels/motels, lodges of any kind, and guest rooms that are used for sleeping purposes must have smoke detectors. The detectors must sound an alarm that is audible in all sleeping areas of the individual dwelling unit in which they are located. Smoke detectors and inspections are required

  • In new construction
  • When one or more sleeping rooms are added or created in existing residential buildings
  • Whenever an addition, alteration or repair to a house or residential unit requires a building permit (excluding issuance of a permit for exterior surface repairs such as chimney repairs and reroofing projects)

Location of Smoke Detectors

When required, smoke detectors in dwelling units are to be located:

  1. In each sleeping room
  2. Outside each sleeping area in the immediate vicinity of the bedrooms
  3. On each story, including basements (but not crawl spaces) and habitable attics
  4. Where stairs lead to other occupied levels, place a smoke detector on the ceiling of the upper level in close proximity to the stairway, located so that rising smoke is not prevented fro reaching the alarm by a door or obstruction
  5. On coffered ceilings, place on top level or within 12 inches of top level on sloped side
  6. Place a minimum of:
  • 20 feet away from cooking appliances
  • 3 feet away from bathrooms with tubs or showers
  • 3 feet away from air supply registers
  • 3 feet away from ceiling fans with paddles

Power Source

New Construction

  • Smoke detectors must receive their primary power from the building wiring when such wiring is served from a commercial source and must be equipped with battery backup.
  • The detector must emit a signal when batteries are low.
  • Wiring must be permanent and without a disconnecting switch other than those required for overcurrent protection.
  • As listed by the California State Fire Marshall

Existing Buildings

Smoke detectors may be solely battery-operated when:

  • Installed in existing buildings
  • The building lacks commercial power
  • The building undergoes alterations, repairs or additions, when:
    • Work does not result in the removal of interior finishes
    • Work is not being done in the attic
    • Work only consists of exterior work or sub-trade repairs, installations, or alterations (plumbing, electrical or mechanical sub-trades)


California Residential Code CRC Section R314

Smoke detectors shall be installed per this code and in accordance with the manufacturer’s installation instructions.

A PDF handout version of this information is available on our Building Handouts and Forms page.