Carbon monoxide is an invisible, odorless gas that can be dangerous when it builds up indoors. Because it cannot be seen or smelled, carbon monoxide detectors play a critical role in home safety. Knowing how many carbon monoxide detectors you need and where to place them helps reduce risk and provides early warning if levels become unsafe.
This guide explains how many carbon monoxide detectors are recommended for a home, where they should be installed, and when they are required.
Do You Need a Carbon Monoxide Detector?
Carbon monoxide is produced when fuel does not burn completely, which is why homes with fuel‑burning appliances or attached garages should have carbon monoxide detectors for early warning. Common sources include:
- Gas furnaces and boilers
- Water heaters
- Fireplaces and wood-burning stoves
- Gas stoves
- Vehicles running in attached garages
The Centers for Disease Control and Prevention warns that carbon monoxide exposure can cause symptoms ranging from headaches and dizziness to serious illness and death.
Homes that use natural gas, propane, oil, or wood-burning appliances are especially at risk. Even newer homes and appliances can experience carbon monoxide buildup if ventilation is blocked or equipment malfunctions.
RELATED: Carbon Monoxide Detection and Prevention Tips
How Many Carbon Monoxide Detectors Are Recommended?
While exact requirements vary by location, general safety guidance recommends installing carbon monoxide detectors:
- On every level of the home
- Near sleeping areas
- Outside bedrooms or in hallways leading to bedrooms
In many homes, this means at least two carbon monoxide detectors, with additional units recommended for larger or multi-level layouts to ensure every level and sleeping area is covered.
The U.S. Consumer Product Safety Commission recommends placing carbon monoxide alarms near sleeping areas so occupants can hear them if they activate at night.
Where Carbon Monoxide Detectors Should Be Placed
Carbon monoxide detectors should be installed:
- Outside sleeping areas
- On each level of the home, including basements
- At least several feet away from fuel-burning appliances
Avoid placing detectors directly next to stoves, fireplaces, or furnaces, as this can cause false alarms.
Many home security systems come with integrated fire and life safety systems that combine smoke/heat detection, carbon monoxide monitoring, and flood leak sensors for more comprehensive protection.
Are Carbon Monoxide Detectors Required?
Carbon monoxide detector requirements vary by state and local building codes. In many areas, detectors are required in:
- Homes with fuel-burning appliances
- Homes with attached garages
- Rental properties
The National Fire Protection Association provides guidance on carbon monoxide alarm placement and safety standards commonly referenced in building codes.
If you are unsure about local requirements, checking local building codes or rental regulations can provide clarity.
Carbon Monoxide Detectors vs Smoke Detectors
Smoke detectors and carbon monoxide detectors serve different purposes.
- Smoke detectors alert occupants to the presence of smoke or fire
- Carbon monoxide detectors alert occupants to dangerous levels of carbon monoxide gas
Some homes use combination units that monitor both hazards, but each function operates independently and should be tested regularly.
Learn More about Guardian Protection’s Monitored Life Safety Devices
Carbon Monoxide Safety Tips
To reduce carbon monoxide risk:
- Test detectors once a month
- Replace batteries as needed
- Never run vehicles in enclosed spaces, including attached garages, even with the garage door open.
- Keep vents and flues clear
- Schedule regular appliance inspections
Carbon monoxide detectors should be replaced according to manufacturer guidelines, typically every 5 to 10 years, even if they appear to function normally.
Related: What to Do If Your Carbon Monoxide Detector Goes Off
When to Get Additional Help With Carbon Monoxide Safety
If carbon monoxide detectors frequently alarm, fail to respond during testing, or are difficult to place correctly, it may indicate a larger issue with appliances, ventilation, or system design. In these situations, professional guidance can help ensure proper coverage and reliable alerts.
Carbon monoxide detection is often part of a broader home security system that includes properly installed devices and professional monitoring, designed to detect issues early and respond quickly when something goes wrong.
Call 1.800.PROTECT (1.800.776.8328) or request a free quote to get protected with a professionally installed home security system.
Frequently Asked Questions
How many carbon monoxide detectors should a house have?
Most homes should have at least one carbon monoxide detector on every level of the home and near sleeping areas. Larger homes may need additional units.
Is one carbon monoxide detector enough?
One detector may not be enough for multi-level homes or homes with multiple sleeping areas. Additional detectors improve coverage and response time.
Do apartments need carbon monoxide detectors?
Many apartments are required to have carbon monoxide detectors if they contain fuel-burning appliances or attached garages, but specific requirements depend on state and local codes.
Do carbon monoxide detectors need to be hardwired?
Sed utSome detectors are battery-powered, while others are hardwired or connected to home systems. Both can be effective when properly installed and maintained.
How often should carbon monoxide detectors be replaced?
Most carbon monoxide detectors should be replaced every 5 to 10 years. Always follow manufacturer recommendations.
What should I do if my carbon monoxide detector goes off?
If a detector sounds, move everyone outside to fresh air immediately and contact emergency services or a qualified professional to assess the situation.