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Smoke detector placement guide: Where and how to install sensors

Protect your house with perfectly placed smoke alarms.

Chris Monroe/CNET

We often don't think about house fires or other disasters until they strike. But preparation is vital. In most regions, smoke detectors are legally required in residential settings -- and they can significantly improve outcomes in case of fire. The question is, where is it best to mount smoke detectors to keep your property and loved ones safe in case of emergency?

How does a smoke detector work?

Before we dive into where to put fire alarms, it's helpful to understand how smoke detectors work to reduce the risk of devastating fire damage and injuries. There are three types of smoke alarms: photoelectric, ionization and dual smoke detectors. 

A photoelectric detector measures light as it hits the sensor. These types of detectors are best at sensing smoky fires. An ionization detector detects when smoke enters the ionization chamber and the ionized smoke particles get neutralized. The drop in the electrical current will activate the alarm. Ionization detectors are more responsive to flaming fires. A dual-sensor smoke alarm is a combination of both. 

Where should smoke detectors be placed?

According to the NFPA, the best place for smoke detectors is inside and outside the bedrooms and on every level of your home, including the basement. Depending on the size of your home, you may need several smoke detectors. Dual-sensor smoke alarms throughout your interior would most effectively detect both types of early fires. 

Smoke rises, so mounting smoke detectors high -- usually on ceilings -- is the best option. If you choose to mount a smoke alarm on a wall, placing it less than 12 inches from the ceiling would be best. Find a spot away from air ducts, windows or anywhere with a draft that could keep smoke from reaching the detector. Interconnecting all smoke alarms will provide you with more thorough protection, too -- if one detector sounds, they all will.


Different smoke detectors monitor smoke in different ways.

Chris Monroe/CNET

Where to place smoke detector in kitchen

People generally avoid placing a smoke detector in the kitchen for fear of it going off during cooking. But a smoke detector is important in any kitchen simply because fires often start there -- even if you aren't around when they start. To minimize false alarms, detectors should be mounted at least 10 feet from the stove or oven. In a small kitchen, this may be difficult. Your only option may be to place the smoke detector just outside of the kitchen area 10 feet or more from the stove. 

Bedroom areas

Smoke detectors should be placed inside the bedroom and just outside the bedroom areas, such as in a hallway. If you don't have enough smoke detectors to place them everywhere, locate one outside the bedrooms in a spot where everyone sleeping could hear the alarm. As mentioned, interlinking wireless or wired smoke detectors helps solve the audibility problem. For example, if the smoke detector in the basement of a two-story home goes off in the middle of the night, interlinked smoke alarms will sound throughout the house, quickly alerting everyone who is sleeping upstairs. 


Don't forget to add a smoke detector in the basement. Interlinking is ideal to alert you if there's smoke in the basement. Otherwise, you may not hear the alarm until the fire spreads to other areas.

How to install a smoke detector

Battery-operated smoke detectors are some of the simplest home security devices to install. They typically come ready to go right out of the box -- all you need to do is mount it. You can follow the manufacturer's instructions for how to install your specific smoke detector, but generally, the steps are consistent.

  1. Unpack the detector and read the documentation.

  2. Install the battery or pull the protective tab out from the battery to activate the alarm.

  3. Choose a draft-free spot on the ceiling or on a wall 12 inches from the ceiling. 

  4. Attach the mounting bracket.

  5. Connect the smoke detector.

  6. Test the smoke detector by pressing the "Test" button. It should make a loud sound that can be easily heard in the general vicinity.

Wired smoke alarms may require an electrician who is able to make the connections and interlink them. 

Smoke detector maintenance

Smoke detectors don't require much maintenance other than to periodically check the battery or electrical connection. Make it a habit to test your detectors once per month by pressing on the test button to ensure the smoke alarm sounds. If you hear chirping, the detector's battery is probably low and should be replaced. Even if your alarm doesn't chirp, replace the batteries on all your smoke detectors once per year. 


If your smoke alarm is chirping, it may be time to switch the batteries.


Do smoke detectors need to be replaced?

If you properly maintain your smoke detector by replacing the battery annually, you won't normally need to replace the whole device. However, some smoke alarms come with a nonreplaceable battery installed. They typically last for 10 years. If the alarm on this type of model chirps, the battery is low and it's time to replace the smoke detector.

What to do if your smoke detector goes off

Understanding fire safety can make the difference between life and death. It's important that everyone in the family recognizes what the sound of the smoke alarm means and what to do. A fire alarm should always be taken seriously, even after several false alarms. Even small children can be taught what to do if a fire alarm goes off. 

A home safety plan can be vital so that everyone at home knows what to do in case of an emergency. Having an exit plan in case of fire including where everyone should meet outside of the home is essential.

Smoke detector false alerts happen. If you hear a smoke alarm, check for the source of the smoke before calling 911. A small grease fire in a pan, for example, can be easily extinguished. However, if there is heavy smoke or a fire you can't control, evacuate the home right away and call 911.

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