Where does Chicago require carbon monoxide alarms?

Chicago Chimney & Fireplace Repair · October 28, 2026

The state rule every Illinois home starts with

The Illinois Carbon Monoxide Alarm Detector Act, 430 ILCS 135, has applied since January 1, 2007. Section 10 says every dwelling unit needs at least one approved, working CO alarm within 15 feet of every room used for sleeping. A building with more than one unit follows the same rule in each unit.

The law reaches any home that burns fossil fuel for heat, hot water or cooking, or that has an attached garage. The Office of the State Fire Marshal's fact sheet lists wood among those fuels, so a wood-burning fireplace counts just as a gas furnace does. A combined smoke and CO unit is allowed if it clearly tells you which hazard it is warning about, and the alarm can run on batteries, plug in with a battery backup, or be hard-wired with a battery backup.

The State Fire Marshal points out that the Act is enforced by the local authority, which may add its own rules. Chicago did.

What Chicago adds, room by room

The City of Chicago Department of Buildings page on carbon monoxide alarms covers new and existing homes with a possible CO source, and it names wood- and gas-burning fireplaces and heating stoves directly. Here is how the city's placement rules work through a typical house:

• Every bedroom: an alarm within 15 feet of the door, the same as state law.
• A bedroom that has its own fireplace or a fuel-burning appliance: an alarm inside that bedroom. Older Chicago homes with a fireplace upstairs are the ones this catches.
• The basement or utility room: an alarm in the same room as every fuel-burning furnace, boiler and water heater. A furnace in one room and a water heater behind a separate door means two alarms.
• Homes with air ducts that connect to a space holding a furnace or fireplace, or with a door straight into a garage, are covered too.
• An all-electric home with no attached garage is not covered by the city rule.

Who is responsible, and what it costs to ignore

The city puts the duty to provide alarms on the owner, along with replacing failed or expired ones and telling occupants in writing that they must test them. Occupants keep batteries working, test the alarms and report a dead one to the owner in writing. The Department of Buildings says owners face $500 to $2,000 per day for each violation, and that the reason an alarm is missing does not matter.

Under state law, willfully failing to install or maintain alarms is a Class B misdemeanor, and tampering with one or pulling its batteries is a Class A misdemeanor the first time. The city page adds that 3-1-1 can point homeowners to free or low-cost alarm programs.

Why the chimney belongs in the same conversation

An alarm tells you carbon monoxide is already in the room. The chimney is one of the ways it gets there. A blocked flue, a collapsed clay tile, a nest in an unused flue or a water heater left alone in a flue built for two appliances can all push exhaust back into the house.

The same city page says that if you have a vented fireplace, you should have your chimney cleaned every year. NFPA 211, the national standard for chimneys and vents, calls for an inspection at least once a year. Nicor Gas makes the same point for gas appliances and warns that snow drifting over a gas vent can cause carbon monoxide to build up indoors.

Our inspection is free. We go through the chimney from the top to the firebox and the appliance connections in the basement, take photos, and give you a written price for anything that needs work. We do not install or test alarms, but we will tell you which rooms hold a fireplace or fuel-burning appliance so you can check your alarms against the city's list.

If an alarm goes off

The City of Chicago and Peoples Gas both say the same thing: leave the building and call 911. If you smell gas, leave first and call from outside. In Chicago that is Peoples Gas at 866-556-6002, and in most suburbs it is Nicor Gas at 888-642-6748. Do not use light switches or start a car on the way out.