Carbon Monoxide Detector Requirements by State (2026 Guide)

Which states require carbon monoxide detectors — and in which homes?

Short answer: Carbon monoxide detector requirements by state fall into three patterns: most states have a statute requiring CO alarms in at least some residential buildings, a smaller group requires them through their building code's adoption of the International Residential Code, and several do both. What varies is coverage — some states cover every dwelling, while others only trigger at new construction, sale, or rental, or only in homes with fuel-burning appliances or an attached garage. The table below maps the patterns state by state, from the National Conference of State Legislatures' statute compilation.

There is no single federal law requiring CO alarms in private homes. What exists instead is a patchwork: state statutes, state building codes built on the International Residential Code's Section R315, and local amendments layered on top. The National Conference of State Legislatures (NCSL) maintains the authoritative compilation of state CO detector statutes, which this guide summarizes — more than 40 states plus the District of Columbia appear in it, alongside a further group whose requirements arrive through building-code adoption instead of statute.

This guide is written for homeowners and landlords confirming what applies to their property, buyers and sellers mid-transaction in sale-trigger states, and safety managers responsible for lodging, day-care, or care facilities. It covers the three requirement patterns, the full state table, what the UL 2034 listing on a compliant alarm actually certifies, IRC R315's placement baseline, and a worked compliance example.

Why this matters.
The CDC attributes more than 400 U.S. deaths and roughly 100,000 emergency-department visits every year to unintentional, non-fire carbon monoxide poisoning — a gas you cannot see, smell, or taste. State legislatures responded with alarm mandates, and in sale-trigger states like Colorado a missing CO alarm can legally stall a real-estate closing. See the CDC's carbon monoxide guidance for the health baseline behind these laws.

The three ways states require CO detectors

Pattern 1: a standalone statute

Most states in the NCSL compilation wrote CO alarms directly into law. Statutes tend to be specific about which buildings are covered and when the duty attaches — for example, Colorado's statute covers single- and multi-family dwellings with fuel-burning equipment, a fireplace, or an attached garage, and attaches at sale, transfer, or new construction.

Pattern 2: the building code route

A second group — including Alabama, Idaho, Kentucky, New Mexico, North Dakota, South Carolina, and Wyoming — requires CO alarms not by statute but because their statewide building codes adopt the International Residential Code. IRC R315 requires CO alarms in new dwellings that have a fuel-fired appliance or an attached garage, which means the requirement reaches new construction even in states with no CO statute on the books.

Pattern 3: both at once

States like Florida, North Carolina, Tennessee, Utah, and West Virginia enforce through statute and code adoption simultaneously — a statute covering specific occupancies, plus the IRC baseline sweeping in new residential construction.

Carbon monoxide detector requirements by state: the table

Summarized from the NCSL statute compilation. Statutes are amended regularly and cities layer local rules on top — treat this as a map, and confirm the current text with your authority having jurisdiction (AHJ) before a transaction or inspection.

If your state isn't in the table, that does not mean no requirement applies — several remaining states regulate specific occupancies (Delaware covers lodging; Nevada covers elder-care facilities; Montana covers rentals; Oklahoma requires warning stickers on motorized vessels), and county or city codes frequently go further than the state. When in doubt, ask your AHJ or fire marshal.

What IRC R315 requires in new construction

The International Residential Code's Section R315 is the baseline most building departments enforce for new one- and two-family homes: carbon monoxide alarms are required when the dwelling contains a fuel-fired appliance or has an attached garage with an opening into the dwelling, and they must be installed outside each separate sleeping area in the immediate vicinity of the bedrooms. In new construction the alarms must draw primary power from the building wiring with battery backup. That "fuel-fired appliance or attached garage" test is why an all-electric house with an attached garage still needs CO alarms under the code — vehicles idling in the garage are a CO source with no gas meter involved.

What the UL 2034 listing certifies

Nearly every state statute and code provision requires alarms "listed" for the purpose — and for single- and multiple-station residential CO alarms, that listing standard is UL 2034 (Iowa's statute names it explicitly). UL 2034 deliberately does two things at once: it requires alarms to respond to dangerous CO concentrations, and it requires them not to alarm at the low, transient levels common near kitchens and roadways — which is why a UL 2034 alarm is a life-safety device, not a low-level exposure monitor.

Workplaces run on entirely different numbers — OSHA's permissible exposure limit for CO is a time-weighted occupational calculation, covered separately in our OSHA CO monitoring requirements guide — don't confuse residential alarm thresholds with occupational monitoring duties.

Where CO alarms go (and where they shouldn't)

The consistent placement rules across CPSC guidance, IRC R315, and the state statutes: one alarm outside each separate sleeping area (Illinois specifies within 15 feet of sleeping rooms, Minnesota within 10), at least one on every level of the home including basements, and near — not inside — the likely CO sources. Keep alarms out of the garage itself and at least 10–15 feet from fuel-burning appliances to avoid nuisance triggers during normal startup, and never behind furniture or drapes; CO mixes with room air, so ceiling or knee-wall height both work per manufacturer instructions.

Worked example: bringing a Colorado home into compliance at sale

Affiliate disclosure: the Amazon buttons below are affiliate links — WC Safety earns a commission on qualifying purchases at no cost to you.

Colorado is a sale-trigger state: a 1998 two-story house with a gas furnace and an attached garage must have compliant CO alarms before the closing. Here is the walk:

1. Confirm the trigger applies. Gas furnace and attached garage — either one puts the home inside Colorado's statute at sale or transfer. The listing agent's inspection checklist will look for alarms within 15 feet of each bedroom entrance.
2. Count the required locations. Three bedrooms across one hallway = one alarm in that hallway; add one per additional level including the basement with the furnace: three alarms minimum for this floor plan.
3. Choose listed hardware for each spot. A plug-in with battery backup like the First Alert CO606 suits the hallway outlet (our CO606 review covers its digital-display sibling models). Check price on Amazon
4. Use sealed 10-year units where outlets are scarce. The basement and upper landing take 10-year sealed-battery units like the Kidde COBD10 (see our Kidde Nighthawk review for the battery lineup) — or a combination unit like the X-Sense SC07 where a smoke alarm location and a CO location coincide near the garage door. Check price on Amazon
5. Test, date, and document. Test each unit per the procedure in how to test a smoke and CO alarm, write install dates on the brackets, and leave the manuals on the kitchen counter for the buyer's walk-through — inspectors in sale-trigger states document alarm presence in the closing file.

The full lineup we've evaluated is in the CO detectors collection, with ranked picks in the best CO detectors guide and the garage-specific scenario in best garage CO detector.

Landlord and renter duties

Rental triggers are the fastest-moving part of this law family: Montana covers rental dwellings outright, Pennsylvania covers multi-family rentals with fossil-fuel equipment, Oregon attaches at every new tenancy, and New Jersey re-checks at each change of occupancy. The pattern that generalizes: the landlord installs and replaces, the tenant maintains batteries mid-tenancy and reports failures in writing. Landlords equipping units in bulk tend toward sealed 10-year units precisely because there are no batteries to pull — the Kidde vs First Alert comparison maps the two dominant ecosystems.

Edge cases the statutes actually name

Boats

Minnesota's statute reaches motorboats with enclosed accommodation spaces, and Oklahoma requires CO warning stickers on motorized vessels — houseboat and cabin-cruiser generators are recurring CO fatality sources.

Generators

Louisiana ties a CO alarm requirement to standby generator installations — and after any hurricane season, portable-generator exhaust is among the CDC's leading CO poisoning causes. If a transfer switch went in, an alarm should have too.

Day cares and care facilities

Texas, Iowa, California, Virginia, and Tennessee all name child-care operations specifically; Nevada and Pennsylvania name care facilities. If you operate one, your licensing inspection almost certainly includes CO alarm verification.

Frequently asked questions

Is there a federal law requiring carbon monoxide detectors in homes?

No. Residential CO alarm requirements come from state statutes, state building codes, and local ordinances. The federal role is indirect — the CPSC regulates and recalls the alarms themselves, and OSHA governs workplace CO exposure, which is a separate regime covered in our OSHA CO guide.

Which states require CO detectors in all existing homes?

Illinois and Minnesota are the clearest examples — both cover existing dwellings outright, with alarm-to-bedroom distance written into the statute (15 and 10 feet respectively). Massachusetts, Maryland, and Wisconsin reach most existing homes through their fuel-equipment and garage conditions.

Which states require CO detectors when selling a house?

Colorado, New York, Washington, Louisiana, Maine, Nebraska, and Oregon all attach requirements at sale or transfer in the NCSL compilation. In those states a missing alarm surfaces on the inspection report and can hold up closing.

Do I need a CO detector if my house is all-electric?

Check the garage: under IRC R315 and most fuel-condition statutes, an attached garage with a connecting opening triggers the requirement even with no gas service, because vehicle exhaust is a CO source. An all-electric, detached-garage home is outside most mandates — though the CPSC still recommends an alarm.

What does UL 2034 mean on a CO alarm?

UL 2034 is the listing standard for residential single- and multiple-station CO alarms. It certifies the alarm responds within set windows at 70, 150, and 400 ppm — and stays quiet below them to prevent nuisance fatigue. Statutes that say "listed" or "approved" mean this listing; Iowa's names it verbatim.

What CO level sets off a detector?

A UL 2034 alarm must sound within 60–240 minutes at 70 ppm, 10–50 minutes at 150 ppm, and 4–15 minutes at 400 ppm. It is designed to track dose (concentration over time), not to display every low reading — that's why alarms with digital displays show transient levels the sounder ignores.

Where should carbon monoxide detectors be installed?

Outside each sleeping area, on every level including the basement, and per manufacturer height instructions — CO mixes with air rather than pooling at the floor. Keep units 10–15 feet from fuel-burning appliances and out of the garage itself. Room-by-room mounting logic shares the geometry in our smoke detector placement guide.

Are combination smoke and CO alarms code-compliant?

Yes, when they carry both listings (UL 217 for smoke, UL 2034 for CO) — the X-Sense SC07 is the pattern. Combination units satisfy both requirements at locations where the two placement rules overlap, like a hallway outside bedrooms. The sensor-type side of that decision is covered in our companion guide to photoelectric vs ionization smoke detectors.

How long do carbon monoxide detectors last?

CO sensors deplete: 5–7 years for older electrochemical cells, 10 years for current sealed units — the end-of-life date is printed on the back and the unit chirps a distinct end-of-life signal. Replacement at the printed date is a manufacturer requirement, not a suggestion.

Do landlords have to provide carbon monoxide detectors?

In rental-trigger states — Montana, Oregon, Pennsylvania, New Hampshire, New Jersey, Maine, North Carolina, Virginia among them — yes, installation is the landlord's duty, typically with tenant battery-maintenance duties mid-tenancy. Even without a state statute, many cities impose it through rental licensing.

Does a gas stove alone trigger CO detector requirements?

In fuel-condition states, yes — a gas range is a fuel-burning appliance, which satisfies conditions like Colorado's, Massachusetts', or Wisconsin's. It's also the appliance most likely to produce chronic low-level CO when misadjusted, which is where display-equipped alarms earn their keep.

Are CO detectors required in hotels and Airbnbs?

Hotels and lodging are named in many statutes (Maine, New Jersey, Vermont, Wisconsin, West Virginia, North Carolina, Delaware). Short-term rentals typically inherit the dwelling rules of their state plus platform requirements — both major booking platforms ask hosts to declare CO alarms, and sale/rental-trigger states apply to the underlying property.

Do CO detector requirements apply to RVs or boats?

Boats with enclosed accommodation spaces are named in Minnesota's statute, and Oklahoma requires vessel warning stickers. RVs are governed by RVIA standards rather than state dwelling statutes — but any RV with a generator, furnace, or attached propane appliance is a textbook CO environment and should carry a listed alarm regardless.

How many CO detectors does a two-story house with a basement need?

Three at minimum under the every-level-plus-sleeping-areas pattern: one outside the bedrooms, one on the main level, one in the basement — more if bedrooms sit on separate wings. The worked example above prices out exactly this build.

What's the difference between a CO alarm and a low-level CO monitor?

A UL 2034 alarm is legally sufficient and deliberately ignores brief low-level readings. Low-level monitors alarm at 10–25 ppm for sensitive occupants — useful for pregnancy, cardiac conditions, or CO-cautious buyers — but they supplement, not replace, the listed alarm the statute asks for.

Do carbon monoxide laws require hardwired detectors?

Only in specific cases: new construction under IRC R315 requires primary power with battery backup, and Rhode Island requires hard-wired or supervised wireless in three-family dwellings. Retrofit requirements in existing homes are nearly always satisfiable with battery or plug-in units.

Further reading on this site

• Best carbon monoxide detectors 2026 — ranked picks across plug-in, battery, sealed 10-year, and smart units.
• CO detectors collection — every alarm we've evaluated in one place.
• OSHA CO monitoring requirements — the workplace regime: PELs, monitoring, and employer duties.
• Best garage CO detector — the attached-garage scenario that triggers half these statutes.
• Kidde vs First Alert CO alarms — the two dominant alarm ecosystems compared.
• Photoelectric vs ionization smoke detectors — the smoke-side companion for combination-alarm decisions.