March 2026 · 11 min read

Landlord's Guide to Carbon Monoxide Detector Laws

Carbon monoxide kills over 400 Americans annually and sends 50,000 to the emergency room. Most states now require CO detectors in rental properties — and the penalties for non-compliance can be severe.

Carbon monoxide (CO) is colorless, odorless, and lethal. Unlike smoke, you can't see it, smell it, or taste it. A malfunctioning furnace, water heater, or gas stove can fill a rental unit with deadly CO levels while tenants sleep. The only defense is a working carbon monoxide detector.

As a landlord, you're almost certainly required to install and maintain CO detectors in your rental properties. But the specifics — where to install them, how many you need, who's responsible for batteries, and what happens if you don't comply — vary significantly by state.

This guide covers the legal requirements, practical installation guidelines, and liability implications every landlord needs to know.

Which States Require CO Detectors in Rentals?

As of 2026, the vast majority of states have some form of carbon monoxide detector requirement for residential properties, including rentals. Here's the breakdown:

States With Mandatory CO Detector Laws for Rentals

These states explicitly require landlords to install CO detectors in rental properties:

• California — Required in all dwelling units with fossil fuel appliances, fireplaces, or attached garages. Must be installed outside each sleeping area. (CA Health & Safety Code §17926.1)
• New York — Required in all residential properties. Must be within 15 feet of every sleeping room. Landlord must provide and install; tenant responsible for batteries in battery-only units.
• Illinois — Required within 15 feet of every sleeping area in units with fossil fuel appliances, fireplaces, or attached garages.
• Massachusetts — Required on every habitable level of the dwelling. Among the strictest requirements in the country.
• Colorado — Required in all residential properties with fuel-burning appliances, fireplaces, or attached garages.
• Texas — Required in all residential rental properties with attached garages or fuel-burning appliances. Must be installed per manufacturer instructions.
• Florida — Required in new construction and substantially renovated buildings. Existing rentals must comply when any building permit is issued.
• Oregon — Required in all rental dwellings. Landlord must install; landlord responsible for replacement.
• Washington — Required in all rental properties. Must be installed per the state building code.
• Maryland — Required in all residences with fuel-burning appliances or attached garages.
• Virginia — Required in rental properties with fuel-burning appliances, fireplaces, or attached garages.
• Pennsylvania — Required in all new construction. Many municipalities extend this to existing rentals.
• New Jersey — Required in all residential units. One of the most comprehensive state laws.
• Connecticut, Maine, Michigan, Minnesota, Montana, New Hampshire, Rhode Island, Vermont, Wisconsin — All require CO detectors in rental properties with some variation in triggers and placement.

States Without Statewide CO Detector Laws

A handful of states — including Alabama, Mississippi, Arkansas, and South Dakota — do not have statewide CO detector requirements. However:

• Local municipalities may have their own requirements
• Building codes (IBC/IRC) adopted by the state may still require CO detection in new construction
• The absence of a law doesn't protect you from liability — if a tenant is harmed by CO and you didn't provide detectors, you face significant negligence claims

Bottom line: Even if your state doesn't legally require CO detectors, install them anyway. A $30 detector is trivial compared to the liability of a CO poisoning incident.

Where to Install Carbon Monoxide Detectors

Most state laws and the National Fire Protection Association (NFPA 720) recommend the following placement:

• Outside each sleeping area — Within 15 feet of bedroom doors. This is the most universally required location because CO poisoning is most dangerous when people are sleeping.
• On every habitable level — Including basements and finished attics. Required in many states (Massachusetts, New Jersey, Connecticut, etc.).
• Near fuel-burning appliances — Within 10 feet of furnaces, water heaters, gas stoves, and fireplaces. Not inside the utility room (CO detectors in humid or dusty areas produce more false alarms) but nearby.
• In attached garages or adjacent rooms — Cars produce CO. If the garage connects to the living space, a detector near that connection point is critical.

Placement Height

CO is roughly the same weight as air, so it distributes evenly in a room. This means:

• Wall-mounted detectors should be at least 5 feet off the floor
• Ceiling mounting works fine (unlike some outdated advice that said CO detectors should be low)
• Don't install within 5 feet of cooking appliances (reduces false alarms)
• Don't install in bathrooms or areas with high humidity
• Follow manufacturer instructions — they've been tested at specific placements

Types of CO Detectors

Not all CO detectors are equal. Here's what to know:

Battery-Powered

• Pros: Easy to install, works during power outages
• Cons: Batteries need regular replacement (9V batteries typically last 1 year; lithium batteries last 5–10 years)
• Best for: Existing properties where hardwiring isn't practical

Hardwired With Battery Backup

• Pros: Most reliable. Powered by home electrical system with battery backup during outages. Required in many states for new construction.
• Cons: Requires professional installation. More expensive upfront.
• Best for: New construction, renovations, or when replacing existing hardwired smoke detectors

Combination Smoke/CO Detectors

• Pros: One device handles both requirements. Fewer devices on walls/ceilings.
• Cons: If one sensor fails, you might need to replace the entire unit. Placement requirements for smoke and CO detectors differ slightly.
• Best for: Landlords wanting to simplify compliance

Smart/Connected CO Detectors

• Pros: Send alerts to your phone. Interconnected units all alarm if one detects CO. Self-testing features. Battery life monitoring.
• Cons: More expensive ($100–$150 per unit). Require Wi-Fi for remote alerts.
• Best for: Landlords who want remote monitoring of vacant properties or premium units

Recommended brands: Kidde, First Alert, Google Nest Protect. All meet UL 2034 certification standards (the minimum required by most state laws).

Who's Responsible for What?

This is where confusion — and disputes — arise. Here's the general breakdown, though your state may vary:

Landlord's Responsibilities

• Purchase and install CO detectors before tenant move-in
• Ensure they're working at the time of move-in (test them during your move-in inspection)
• Replace detectors that have reached end of life (most CO detectors expire after 5–7 years — check the manufacture date on the back)
• Replace detectors that are found non-functional during inspections
• Maintain hardwired systems including electrical connections

Tenant's Responsibilities (in most states)

• Replace batteries in battery-operated detectors (except in some states like Oregon, where the landlord is responsible for all maintenance)
• Notify the landlord if a detector is malfunctioning, beeping, or not working
• Do not disable or remove CO detectors. Many states make this a lease violation that can be grounds for eviction.
• Test detectors regularly (though you can't enforce this — educate instead)

Include CO detector responsibilities in your lease agreement. Be specific about who handles batteries, who reports issues, and what happens if a tenant disables a detector. See our guide on essential lease clauses.

Replacement Schedule

CO detectors don't last forever. The sensors degrade over time and eventually stop detecting carbon monoxide — even if the unit still powers on and tests fine when you push the button.

• Standard CO detectors: Replace every 5–7 years (check manufacturer specification)
• Combination smoke/CO detectors: Replace every 7–10 years
• Batteries (9V): Replace annually
• Sealed lithium battery units: Replace the entire unit when the sealed battery dies (typically 10 years)

Add detector replacement to your preventive maintenance schedule. When you replace a detector, write the installation date on the back with a permanent marker. This makes future inspections simple.

Penalties for Non-Compliance

Penalties for failing to install required CO detectors range from annoying to devastating:

• Fines: $200–$5,000 per violation in most states. California can fine up to $5,000 per unit per violation. New York City fines start at $250 per violation.
• Failed inspections: In states requiring rental inspections (New Jersey, parts of Massachusetts, etc.), missing CO detectors will fail the inspection — meaning you can't legally rent the unit.
• Liability for injury or death: If a tenant suffers CO poisoning in a property without required detectors, your liability is essentially unlimited. Personal injury attorneys take these cases on contingency, and juries are extremely sympathetic to CO poisoning victims. Settlements and verdicts routinely reach six and seven figures.
• Insurance implications: Your landlord insurance policy may deny claims related to CO incidents if you weren't in compliance with state requirements. Read about what landlord insurance actually covers.
• Criminal charges: In extreme cases (negligence resulting in death), landlords have faced criminal charges for failing to provide working CO detectors.

Common CO Sources in Rental Properties

Knowing where CO comes from helps you prioritize detector placement and maintenance:

• Gas furnaces: The most common source. Cracked heat exchangers, blocked flues, and improper combustion can produce dangerous CO levels. Annual HVAC service is essential.
• Gas water heaters: Especially older tank-style units with corroded venting.
• Gas stoves and ovens: Minor CO production during normal use, but malfunctioning burners or using the oven for heating can produce dangerous levels.
• Fireplaces and wood stoves: Blocked chimneys, closed dampers, or backdrafting can push CO into the living space.
• Attached garages: Cars idling in garages, gas-powered tools, or generators in attached garages can push CO into the home through shared walls and doors.
• Portable generators: The #1 cause of CO deaths during power outages. If tenants use portable generators, educate them about outdoor-only use.

Schedule annual servicing of all fuel-burning appliances. A $150 furnace inspection is cheap insurance against a CO incident.

Documenting Compliance

Keep records proving your CO detector compliance. If an incident occurs, "I installed them" isn't enough — you need documentation.

• Purchase receipts for all CO detectors
• Installation photos showing detectors in place with dates
• Move-in checklist documenting that detectors were tested and working at the start of tenancy
• Inspection records from annual or semi-annual property inspections
• Maintenance logs showing detector replacement dates
• Lease clauses assigning battery replacement responsibility to tenants

Use a property management platform like Rentlane to track inspection schedules and store documentation digitally. If you're ever challenged on compliance, having organized records is your best defense. See our full documentation guide.

The Bottom Line

Carbon monoxide detectors are cheap, easy to install, and legally required in most states. There is no rational argument against installing them in every rental property you own — even if your state doesn't technically require them.

The cost: $25–$40 per detector, installed in minutes. The alternative: a potential wrongful death lawsuit, criminal charges, and the knowledge that someone was harmed in your property because of a $30 device you didn't install.

Install them. Test them at every inspection. Replace them on schedule. Document everything. It's one of the simplest and most important things you can do as a landlord.