Colorado’s carbon monoxide detector law requires an operational CO alarm within 15 feet of every sleeping room in any residence that has a fuel-burning appliance, a fireplace, or an attached garage. The rules sit in Title 38, Article 45 of the Colorado Revised Statutes, and they split responsibility among sellers, landlords, and tenants depending on the property type and what triggered the obligation. There is no criminal penalty in the statute itself, but noncompliance opens the door to civil liability and local code enforcement.
Which Homes Are Covered
The law turns on two physical features. If a residence contains a fuel-burning heater, appliance, or fireplace, or has an attached garage, it falls within the statute. A home that is entirely electric and has no attached garage is outside the law’s scope. Add a gas furnace, wood stove, or other fuel-burning appliance later, and the requirement takes effect.
Coverage also depends on a triggering event occurring on or after July 1, 2009. Three sections of Article 45 each define their own trigger:
- Single-family homes under CRS 38-45-102: the sale of the home, or issuance of a building permit for interior work, appliance replacement, or adding a sleeping room.
- Multi-family dwellings under CRS 38-45-103: condominiums, cooperatives, and apartment buildings with more than one dwelling unit follow similar placement rules.
- Rental properties under CRS 38-45-104: a building permit for interior work, or any change in tenant occupancy after July 1, 2009.
An owner-occupied home that hasn’t been sold, rented, or renovated since before that date is technically not subject to the statute. The carbon monoxide risk is the same regardless, and installing alarms is advisable whether the law compels it or not.
Where Alarms Have to Be Installed
CRS 38-45-102 requires a carbon monoxide alarm within 15 feet of the entrance to each room used for sleeping. Bedrooms on different levels each need coverage on their own level. The statute also allows placement “in a location as specified in any building code adopted by the state or any local government entity,” so a city or county rule can add locations the state doesn’t specifically name.
Homes with fuel-burning appliances in isolated spaces like basements may need alarms beyond the 15-foot rule if a local code adopts National Fire Protection Association standards. NFPA guidance recommends alarms on every level and near potential CO sources.
What Counts as an Approved Alarm
Colorado law defines a carbon monoxide alarm with specific requirements. The device must produce a distinct audible alarm and be listed by a nationally recognized independent testing laboratory such as UL. Combination smoke and CO alarms are allowed, but the unit has to clearly differentiate between the two hazards through distinct sounds or voice signals.
Four installation methods are recognized: hardwired into the home’s electrical system, plugged directly into an outlet with battery backup, wired with battery backup, or connected to an electrical panel. Battery-powered alarms are also allowed if they are mounted on the wall or ceiling in accordance with NFPA Standard 720.
Carbon monoxide sensors degrade. Most manufacturers rate their alarms for about seven years, after which the sensor becomes unreliable. Alarms produced after August 2009 include an end-of-life chirp when the unit needs replacement. Check the manufacture date printed on the alarm and replace it when the manufacturer’s recommended lifespan expires, even if it still seems to work.
Selling a Home in Colorado
The seller of any single-family home offered for sale on or after July 1, 2009 must make sure an operational CO alarm is properly installed before closing, if the home has a fuel-burning appliance, fireplace, or attached garage. Placement follows the 15-foot rule or an applicable local building code.
Home inspectors routinely flag missing or expired alarms, and buyers commonly require installation as a condition of closing. A sale that closes without compliant alarms exposes the seller to civil liability if someone is later harmed by CO exposure. CRS 38-45-106 preserves a buyer’s remedies against a non-compliant seller.
What Landlords Must Do
CRS 38-45-104 sets landlord duties more narrowly than many landlords realize. Before a new tenant moves in, the landlord has to replace any CO alarm that was stolen, removed, missing, or not working after the previous tenancy, and provide the batteries needed to make the alarm operational when the tenant takes possession.
Once a tenant is in the unit, the landlord’s ongoing duty is triggered by written notice. If a tenant notifies the landlord in writing that an alarm is missing, stolen, or not working, the landlord must replace it. If the tenant reports a deficiency the tenant cannot fix, the landlord must correct it. Outside those situations the statute says the landlord is not responsible for routine maintenance, repair, or battery replacement.
A verbal complaint doesn’t trigger the landlord’s statutory duty. Put every maintenance request in writing and keep a copy.
What Tenants Must Do
Tenants carry the day-to-day maintenance. Under CRS 38-45-104, the tenant must keep, test, and maintain all CO alarms in good repair. When batteries need replacement, the tenant notifies the landlord in writing. If an alarm goes missing, stops working, or has a deficiency the tenant cannot correct, written notice to the landlord is required.
No one may remove batteries or disable a CO alarm except during inspection, maintenance, or repair. A tenant who disables an alarm takes on responsibility for any resulting harm and may be liable for replacement costs. The same anti-tampering rule appears in CRS 38-45-103 for multi-family buildings.
Federally Assisted Rentals Have Stricter Rules
If a rental unit receives Section 8 Housing Choice Voucher or Project-Based Voucher assistance, HUD’s NSPIRE inspection standards apply on top of state law. Alarms must be installed in the immediate vicinity of each bedroom, or inside each bedroom, when the unit contains a fuel-burning appliance or fireplace. A missing, improperly placed, or nonfunctional alarm is a life-threatening deficiency: the unit fails inspection and the landlord has 24 hours to fix it.
NSPIRE reaches situations state law doesn’t. If a unit is served by a forced-air furnace located elsewhere in the building, the federal rules require an alarm near each bedroom, inside each bedroom, or in the room with the first duct register. If a unit sits one story or less above or below an attached private garage that lacks proper ventilation, an alarm is required near or inside each bedroom regardless of whether the unit itself contains fuel-burning appliances.
What Happens If You Don’t Comply
Article 45 does not impose criminal penalties. CRS 38-45-106 is a liability shield for people who follow the rules: no one can bring a claim against a property owner, agent, or installer for damages resulting from the operation, maintenance, or effectiveness of an alarm that was installed according to the manufacturer’s instructions and the statute.
Fail to install alarms as required, and that shield disappears. If someone is harmed by CO exposure, the owner is exposed to ordinary negligence claims covering medical expenses, lost wages, pain and suffering, and wrongful death damages. Courts don’t need a specific penalty statute to hold a landlord or seller accountable when a safety requirement was ignored.
Local code enforcement is the other consequence. CRS 38-45-105 explicitly authorizes municipalities and counties to adopt their own CO alarm ordinances, and many Colorado cities have incorporated the state requirements into local codes. Denver passed its own CO alarm ordinance in 2009 alongside the state law. Violations can bring citations, fines, or orders to correct deficiencies, and some cities escalate fines for repeat violations. State law is a floor, not a ceiling, so check the local code in addition to the statute.
Reporting a Violation
Tenants who find a missing or nonfunctional CO alarm should notify the landlord in writing first. The statute’s framework requires written notice before the landlord’s duty to act kicks in. Keep a dated copy of everything you send.
If the landlord doesn’t respond, report the issue to the local building code enforcement office or housing authority. Local agencies investigate complaints and can order landlords to correct deficiencies. In municipalities with their own CO ordinances, local enforcement may carry penalties the state statute doesn’t.
Homebuyers who spot missing alarms during inspection can require installation as a condition of closing. If a sale closes without compliant alarms and the buyer later suffers CO exposure, a civil claim against the seller remains available. In severe cases where a landlord repeatedly ignores reports and someone is injured or killed, local prosecutors may pursue action based on general negligence principles. The absence of a criminal provision in Article 45 doesn’t mean there are no consequences; it means the consequences run through civil liability and local code enforcement.