Carbon Monoxide Detector Laws by State (2025): Is Your Home Compliant?

As of 2025, 38 US states have enacted laws requiring carbon monoxide detectors in residential buildings. But 'required' looks very different from state to state. Some states mandate detectors in every sleeping area of every home built before 1978. Others require them only in new construction, or only in units with attached garages. This guide gives you a clear overview of what's required in your state and what landlords must provide for renters.

Why Federal Law Leaves This to States

There is no federal residential CO detector requirement. The Consumer Product Safety Commission (CPSC) recommends CO detectors but does not mandate them. Responsibility falls entirely to state and local governments, which is why requirements vary so dramatically. The National Fire Protection Association's NFPA 720 standard provides a model code — but states choose whether to adopt it.

States with the Strongest Requirements

These states have comprehensive CO detector requirements covering most or all residential buildings:

• California: required in all existing and new single-family homes (since 2011) and all multifamily buildings (since 2013); must be UL listed
• New York: required in all one- and two-family dwellings and all multifamily buildings; landlords must provide and maintain
• Illinois: required in every dwelling unit within 15 feet of rooms used for sleeping; landlords responsible for rental units
• Massachusetts: required in all residential buildings with fossil-fuel-burning equipment or attached garages; one on each level
• Maryland: required in all residential buildings; must be on each floor with sleeping areas
• New Jersey: required in all one- and two-family dwellings with attached garages or fuel-burning equipment; landlords must provide in rentals
• Washington: required in all dwelling units in new construction since 2010; older buildings covered by local codes
• Oregon: required in all dwellings; landlord must install and maintain in rental units
• Minnesota: required in all single-family and multifamily dwellings; one outside each sleeping area

States with Moderate Requirements

These states require CO detectors in new construction or specific building types, but may exempt older buildings or certain occupancies:

• Texas: required in new construction (residential code) and multifamily buildings; older buildings depend on local municipality
• Florida: required in new one- and two-family dwellings built after 2008; local jurisdictions may expand this
• Georgia: required in new construction residential buildings
• Ohio: required in all residential occupancies under the state fire code
• Michigan: required in all one- and two-family dwellings with fuel-burning appliances or attached garages
• Pennsylvania: required in all residential buildings under the Uniform Construction Code
• Virginia: required in all residential buildings; one on each floor with a bedroom
• Colorado: required in all residential dwellings with fuel-burning appliances or attached garages
• Arizona: required in new construction; older buildings subject to local fire code

States with Limited or No State-Level Requirements

These states have limited or no state-level CO detector requirements — though local municipalities may have stricter rules:

• Alabama, Alaska, Arkansas, Idaho, Kansas, Mississippi, Missouri, Montana, Nebraska, North Dakota, Oklahoma, South Carolina, South Dakota, Tennessee, West Virginia, Wyoming — limited or no state-level residential CO detector mandate
• In these states, check your local city or county code — many municipalities have enacted requirements independently of state law
• Even without a legal requirement, CO detectors are strongly recommended wherever fuel-burning appliances or attached garages are present

What Landlords Are Required to Provide

In states with CO detector laws, landlord obligations typically include:

• Providing a working CO detector at the start of each tenancy
• Ensuring detectors are functional and not expired at move-in
• Replacing detectors that malfunction or expire during the tenancy (upon tenant notification)
• Some states require annual testing or written documentation of detector status

What Tenants Are Responsible For

In most states, tenants are responsible for:

• Replacing batteries in battery-operated units provided by the landlord
• Notifying the landlord promptly if a detector malfunctions or reaches end of life
• Not removing or tampering with installed detectors

The Gap Between Legal Compliance and Actual Safety

Even full compliance with your state's CO detector law doesn't guarantee you're protected. Laws generally don't require:

• Replacement of detectors that have passed their sensor expiration date
• Specific sensor technology (electrochemical vs. cheaper alternatives)
• Live PPM displays
• Placement in every sleeping area (some laws require only one per floor)
• Detector testing or certification between tenancies in many states

Legal compliance is the floor, not the ceiling. Regardless of what your state requires, every sleeping area in your home deserves its own current, UL 2034 certified CO detector with a live PPM display — and a sensor that hasn't expired. The AirShield detector meets every state requirement and sets a higher standard with a 10-year electrochemical sensor and real-time OLED display. Landlords can use the Landlord CO Compliance Guide for a full state-by-state breakdown of legal obligations across all 50 states.