Where Should Carbon Monoxide Detectors Be Installed?

Carbon monoxide (CO) detectors only protect you if they’re in the right places. Because CO is colorless and odorless, proper placement is the difference between an early warning and a missed one. If you heat with gas in Greater Vancouver, here’s how to set up your home correctly.

The Core Rule: Every Level, Every Sleeping Area

Install at least one CO detector on each level of your home, including the basement, and one outside every separate sleeping area. Bedrooms are where CO is most dangerous because you may not wake up, so an alarm near sleeping areas is essential. In a multi-storey house, that typically means several detectors.

Where to Place Each Detector

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• Outside bedrooms: In the hallway near sleeping areas so the alarm wakes everyone.
• Near, not on top of, fuel appliances: Keep a detector a reasonable distance from the furnace, water heater, or fireplace, rather than mounted directly on the appliance.
• On every floor: Including basements and the top of stairwells.
• Near an attached garage: A detector just inside the door leading to the garage catches CO from a vehicle left running or from equipment stored there.
• Follow the mounting height in the manual: CO mixes fairly evenly with air, so most models can be placed at various heights; the manufacturer’s instructions take priority.

Where NOT to Install Them

Combination vs. Standalone Units

Combination smoke and CO alarms are convenient and satisfy both needs in one device, but standalone CO detectors are also fine. Whichever you choose, interconnected alarms, where one triggers all, add an extra layer of safety in larger homes. Battery-powered units offer protection during a power outage, while hardwired units with battery backup avoid the chore of frequent battery changes.

How Many Detectors Does a Typical Home Need

A single-storey home with two bedrooms clustered together might need only two units: one in the hallway outside the bedrooms and one near the main living area. A three-storey home with a basement furnace room, main floor living space, and upstairs bedrooms typically needs at least three or four units to properly cover every level and sleeping area under most building code guidance. When in doubt, more coverage is safer than less.

Testing and Replacement

Test every detector monthly using the test button, change batteries as recommended, and note that CO sensors wear out. Most units have an expiry date and need replacing every several years, so check the label and mark your calendar. A silent, expired detector offers no protection.

CO Detectors and BC Building Requirements

Many BC municipalities require CO alarms in homes with fuel-burning appliances or an attached garage, following guidance similar to the BC Building Code and CSA standards for alarm placement. Requirements can vary slightly by municipality and by whether the home is new construction or an older resale, so checking with your local building department is worthwhile if you are unsure what your specific home needs.

What to Do If an Alarm Sounds

1. Get everyone, including pets, outside to fresh air immediately.
2. Do not try to locate the source or open windows on your way out; leave first.
3. Call 911 from outside the home once everyone is safe.
4. Do not re-enter until emergency responders or a licensed technician confirms it is safe.

Detectors Plus Annual Furnace Service

Detectors are your last line of defense; preventing CO at the source is the first. Have your gas furnace inspected each year so combustion and venting issues are caught early. ROMA Heating & Cooling is a TSBC-licensed gas contractor (Gas licence LGA0202903), and our HVAC maintenance plans include annual safety checks. If your CO alarm ever sounds, get everyone outside to fresh air and call 911 first, then arrange a furnace repair or inspection. To book service, request a free estimate or contact our Burnaby team.

Frequently Asked Questions

How many carbon monoxide detectors do I need?

At minimum, one on every level of your home plus one outside each separate sleeping area. Larger or multi-storey homes need more. Follow local requirements and the manufacturer’s guidance.

Should CO detectors go high or low on the wall?

Carbon monoxide mixes fairly evenly with indoor air, so most detectors can be placed at various heights. Always follow the specific mounting instructions in your unit’s manual.

How close to the furnace should a CO detector be?

Keep it near the appliance area but not mounted directly on the furnace, as normal start-up combustion can trigger false alarms. Check your manual for the recommended distance.

How often should I replace my CO detectors?

CO sensors have a limited lifespan and typically need replacing every several years. Check the expiry date printed on the unit, test monthly, and replace batteries as recommended.

Reviewed by the ROMA Heating & Cooling team — TSBC-licensed gas contractor (Gas LGA0202903), serving Greater Vancouver since 1999. Updated June 2026.

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