California smoke and carbon monoxide alarm requirements apply to nearly every home, apartment, condo, and duplex in the state. You need State Fire Marshal–approved smoke alarms inside each sleeping room, in the hallway outside each sleeping area, and on every story of the dwelling. You need carbon monoxide alarms in any home that has a fossil fuel–burning appliance, a fireplace, or an attached garage. Violations are infractions carrying fines up to $200 per offense, and each missing device counts separately.1California Legislative Information. California Code HSC 13113.72California Legislative Information. California Code HSC 17926
Where Smoke Alarms Must Be Installed
Three locations, no exceptions for most homes: inside every room used for sleeping, in the hallway or area immediately outside each separate sleeping area, and on every story of the building including basements and habitable attics.1California Legislative Information. California Code HSC 13113.7 A two-story house with bedrooms only upstairs still needs at least one alarm on the ground floor.
Every unit has to be listed and approved by the State Fire Marshal and installed to the manufacturer’s instructions. That includes placement height, distance from vents, and any restrictions near kitchens and bathrooms that the manufacturer specifies.
Where Carbon Monoxide Alarms Are Required
The CO alarm rule turns on what’s inside the home. You need CO alarms if the dwelling has any fossil fuel–burning heater or appliance, a fireplace, or an attached garage.2California Legislative Information. California Code HSC 17926 “Fossil fuel” here covers gas, oil, kerosene, wood, coal, and other hydrocarbon fuels that produce carbon monoxide when they burn.3Justia. California Health and Safety Code 13260-13263 – Carbon Monoxide Poisoning Prevention Act of 2010 Single-family homes, duplexes, condos, apartments, hotels, and dormitories all fall under the statute.
If your home is fully electric with no fireplace and no attached garage, the CO alarm requirement doesn’t apply to your unit. Placement mirrors the smoke alarm logic: outside each separate sleeping area near the bedrooms, and on every level of the dwelling.2California Legislative Information. California Code HSC 17926 Every device must be State Fire Marshal listed.3Justia. California Health and Safety Code 13260-13263 – Carbon Monoxide Poisoning Prevention Act of 2010 Combination smoke and CO alarms are allowed as long as the unit is certified for both functions.
Battery-Operated or Hardwired
Which type is legal depends on the age of the home.
In existing dwellings, battery-operated smoke alarms are fine as long as local rules don’t say otherwise and the unit carries State Fire Marshal approval.1California Legislative Information. California Code HSC 13113.7 Any newly installed battery unit has to contain a sealed, non-replaceable battery rated for at least ten years. You can no longer install an alarm that runs on standard replaceable batteries.
New construction is stricter. Smoke alarms have to be hardwired to the electrical system with a battery backup, wired without any disconnecting switch other than the circuit breaker, and interconnected so that when one alarm trips, every alarm in the unit sounds.4UpCodes. California Building Code Chapter 9 – Fire Protection and Life Safety Systems Listed wireless alarms can satisfy the interconnection requirement without running wire between rooms.
When a Renovation Triggers an Alarm Upgrade
Pull a building permit for alterations, repairs, or additions valued over $1,000, and the permit office won’t finalize the work until every smoke alarm in the home is a State Fire Marshal–approved device installed in the required locations.1California Legislative Information. California Code HSC 13113.7 The threshold is low enough that most permitted remodels catch it. Alarms added under this rule in existing homes can still be battery-operated, provided they use a sealed ten-year battery. Hardwiring and interconnection are new-construction requirements, not a retrofit obligation.
Rentals: Who’s Responsible
Landlords own the installation, maintenance, and replacement obligation for smoke and CO alarms in rental units, including batteries and expired devices. In multi-unit buildings, that extends to smoke alarms in common stairwells.5UpCodes. California Residential Code R314.8 – Existing Group R-3 Occupancies Rental properties had to be brought into compliance with current placement standards by January 1, 2016.1California Legislative Information. California Code HSC 13113.7
Tenants carry one specific duty. If you notice an alarm that isn’t working, you have to tell the landlord or property manager in writing. A landlord isn’t in violation until they’ve been notified, so the reporting burden sits with you once you know about the problem.
Selling a Home
Sellers of a single-family dwelling have to give the buyer a written statement confirming the property complies with state smoke alarm law.6California Department of Real Estate. Disclosures in Real Property Transactions – RE 6 A missing CO alarm won’t invalidate the sale, but the buyer can recover actual damages up to $100, plus court costs and attorney’s fees, if the home doesn’t meet CO alarm requirements at transfer.2California Legislative Information. California Code HSC 17926 Some cities and counties layer stricter rules on top of state law, so check locally before you list.
Fines and How They Add Up
A smoke alarm violation is an infraction with a maximum fine of $200 per offense.1California Legislative Information. California Code HSC 13113.7 The CO alarm statute uses the same $200 cap but gives the property owner 30 days after notice to fix the problem before the fine can be assessed.2California Legislative Information. California Code HSC 17926 Each missing or noncompliant device is a separate offense, so a home short on alarms in several rooms can accumulate penalties fast. Local ordinances can add requirements and steeper fines on top, as long as they don’t conflict with state law.
Replacement, Testing, and Sensor Type
Every smoke alarm has to be replaced ten years from the manufacture date printed on the housing, or sooner if the manufacturer specifies a shorter service life. Flip the unit over. If you can’t read a date, replace it. Test monthly with the button, and for hardwired units with a replaceable backup battery, follow the manufacturer’s swap schedule.
State law doesn’t require a specific sensor type. Ionization sensors react faster to fast-flaming fires like grease or burning paper. Photoelectric sensors catch slow, smoldering fires, which can burn for hours before flames appear, and are the better fit for bedrooms and living areas. Many newer units combine both sensors, and dual-sensor smoke-CO alarms cover both jobs in one device.