Where (and Where Not) to Place Smoke Detectors and CO Alarms

When it comes to protecting your home and family, smoke detectors and carbon monoxide (CO) alarms are among the most critical safety devices you can install. However, placement matters. Incorrectly located alarms can delay detection, give false readings, or fail to warn you in time. Here is a clear guide to where these life-saving devices should (and shouldn’t) be installed.
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Smoke Detectors: Best Practices
Smoke detectors sense smoke particles in the air, so their position affects how fast they respond.

 ☑  Where to install:

• Inside every bedroom—fires often start at night, so bedroom detectors are essential for early warning while you sleep.
• Outside each sleeping area—place one in the hallway or common area leading to bedrooms.
• At least one alarm on every level of the home—including basements and finished attics.
• On the ceiling or high on walls—smoke rises, so mount detectors on the ceiling (at least 4 inches from the wall) or on walls (4–12 inches from the ceiling).
  

⮾ Where NOT to install:

• In kitchens—cooking smoke can trigger nuisance alarms. Place detectors at least 10 feet away from cooking appliances.
• In bathrooms--steam from showers can cause false alarms.
• In garages—car exhaust can cause false alarms and shorten detector life.​
• Near windows, doors, ceiling fans or ducts—airflow can interfere with sensor function.
  
  

 Carbon Monoxide (CO) Alarms: Best Practices
CO is colorless and odorless, and it mixes evenly with air, so placement differs from smoke alarms.

☑ Where to install:

• Outside each sleeping area—so alarms wake you if CO builds up at night.
• At least one on every level of the home--including basements.
• Near fuel-burning appliances—such as furnaces, water heaters, or fireplaces (but not too close—see below).
  

⮾ Where NOT to install:

• Right next to appliances—place alarms at least 5–10 feet away to prevent nuisance trips from brief CO bursts.
• In kitchens or bathrooms—steam and cooking fumes can affect sensors.
• Directly above fuel-burning devices—warm air currents can prevent proper sensing.
• In overly humid or dusty areas—these can damage the sensor.
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Combination Alarms: Best Practices
Many homes use combination smoke/CO alarms. If you choose these, follow the smoke detector placement rules, since they’re more restrictive.
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Testing and Maintenance: Best Practices

• Test monthly using the “Test” button.
• Replace batteries yearly (or per manufacturer instructions). Most new units now have 10-year batteries.
• Replace entire units every 7–10 years, as the sensors degrade over time.