Home Smoke Detector Placement Guide

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Do you have just one smoke detector in your home?

Chances are, you’ll need more than one.

In fact, many jurisdictions require by law that you install smoke detectors in several locations around your home.

Even if it’s not a legal requirement where you live, we feel it’s good practice to have several smoke detectors fitted throughout your home.

Having good coverage of smoke detectors may even save a life one day.

Disclaimer: Ensure you check and adhere to the specific legal requirements for smoke detectors in a residential building of the jurisdiction where you live. Check with your local fire department on placement and installation requirements specific to your area. We cannot provide professional advice for your situation.

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1. Where Should I place my Smoke Detectors?

It is recommended that smoke detectors be placed:

a) On every level of your home.

The NFPA recommend installing a smoke alarm around your home and make sure there’s a smoke detector on every level – including the basement [2] (Interestingly, at the time of writing this article, the NFPA recommended not placing a fire alarm in an attic [1]). Floors and roofs act as barriers between fires, meaning a fire may be raging on one level without a detector on another level sounding the alarm. That’s why it’s recommended to ensure there’s an alarm on each level.

b) In Every Bedroom.

Once you’ve got one alarm on each level, the NFPA recommends installing an alarm in each bedroom [2]. You’ll be surprised how many jurisdictions have this as a legal requirement. But besides the legal requirements, bedrooms are an ideal place to put your smoke detectors. It will be close to sleeping family members which will increase their chances of waking up if it goes off. It will also ensure a fire close to sleeping family members will be detected quickly.

c) Outside Bedrooms.

If there is a hallway that leads to several bedrooms, it is recommended by NFPA that a smoke alarm be placed in the hallway outside the bedroom as well [2]. If people are sleeping in their bedroom with the door shut, a fire can get out of control in the rest of the house before their alarm goes off in their sealed-off bedroom. Therefore, it’s imperative they’re given a fair early warning about a fire outside their bedroom door.

d) On Stairways.

Smoke and heat travel through stairways as fires spread around homes. This makes the stairway an ideal location for a smoke alarm that will provide an early warning to people in your house.

NFPA recommends that you should place a smoke alarm at the bottom of basement stairs [2]. Occasionally ‘dead air’ can get trapped at the bottom of basement stairs, preventing smoke from moving up the stairwell.

Once you’re Done: Once you have each of the above locations covered, walk around the house and make sure there’s always an alarm within earshot of every corner of the house. If there are locations that won’t hear an alarm, you’ll need to place alarms nearby to ensure the whole house is covered.

2. Where should I NOT place my Smoke Detectors?

Smoke detectors are less effective:

a) Close to cooking appliances.

Even though fires often begin in kitchens, smoke and heat detectors often provide false alarms when placed in kitchens.

For this reason, NFPA recommends that you do not place smoke alarms too close to cooking appliances. This will help prevent false alarms. NFPA recommends that smoke detectors be placed at least 10 feet away from your oven, stove or other cooking appliances [2].

Also consider the 10 feet rule for furnaces or other appliances that emit combustible particles

b) By vents, sliding doors, fans, and windows.

Locations where there is enhanced airflow from outside can decrease the effectiveness of a smoke detector. The NFPA recommends avoid placing your detector directly adjacent to locations where external airflow may interrupt the functioning of the detector [1].

Similarly, placement of a detector near a fan can mess with its effectiveness. The fan pushes away the particles in the air that detectors use to warn you of a fire.

c) In extreme temperature spots.

High and low temperatures can mess with the proper functioning of a smoke alarm. This may lead to false positives where alarms go off when there is no fire present. Prolonged exposure to extreme temperatures can also damage the alarms and cause them not to go off when they should.

NFPA recommends that you should not place smoke alarms in locations where the temperature will regularly rise above 110F (43C) or fall below 40F (4.5C) [1].

e) Adjacent to showers.

Mist from showers can cause smoke alarms to go off when no fire is present. NFPA recommends that you do not place a smoke detector within 3 feet (about 1 meter) of a bathroom door [1]. If you’re struggling with high humidity setting off false alarms from your smoke detector, consider getting a smart smoke detector like the Nest Protect which has Steam Check technology to minimize false positives due to humidity.

f) In dusty areas.

Air that is thick with dust may cause false alarms or over time clog the detection system. It is best to place the alarm away from the dustiest parts of rooms. Lint in your laundry may also have this effect, so keep your laundry clean and dusted regularly [1].

g) In insect infested areas.

Insects can get into detectors and interfere with their effectiveness. If you notice an area has a high amount of insects, consider placing the detector somewhere nearby where the insects are less prevalent.

It is good practice to regularly check the smoke alarm to see if any insects have managed to make their way into the system.

Quick Tip: Never paint, decorate or place stickers over alarms. This can interfere with their effectiveness.

3. How high should I place my Smoke Detectors?

Smoke and heat rise. Therefore, it is recommended that smoke detectors be placed as high as possible in a room, with the exception of the stairwells example outlined earlier.

NFPA recommends placing a smoke detector either on the ceiling itself or high on a sidewall. The current recommendation is that smoke detectors be placed within 12 inches (30cm) of the ceiling [2].

Some ceilings are slanted. In this case, NFPA states to place the smoke detector within 12 inches of the highest point of the ceiling.

But, they also state that if your ceiling has an apex (comes to a peak), do not place the alarm within 4 inches of the apex [2].

4. Which type of Smoke Detector Should I Use?

There are several types of fire detection systems.

The most common and well regarded fire protection alarms are ionization and photoelectric alarms.

a) Ionization

An ionization detector is best for detecting rapid fires that appear out of nowhere.

These detectors go off when fine smoke particles interrupt the electric currents within the alarm. It is best at detecting small smoke particles.

b) Photoelectric

A photoelectric detector is best for detecting slow, smouldering fires. It operates through a beam of light that, when interrupted by smoke particles, sets off the alarm. It is best at detecting larger smoke particles.

c) Heat detectors

A heat detector is not recommended as a comprehensive fire detection system. If you use heat detectors, make sure you area also using an ionization or photoelectric alarm.

d) CO detectors

A CO detector is designed to identify carbon monoxide in the air. Carbon monoxide is a deadly gas that can be emitted during fires. This should not replace a smoke detector, but is often increasingly required by law as an additional type of detector that you need to install in your home.

Consider buying the newer ‘dual sensor’ detectors that use a mix of ionization, photoelectric and CO detection. These all-in-one fire detection systems are a state-of-the-art way to protect your family.

Remember: Check with your local fire station to see whether there is a requirement for a specific type of detector in your area.

5. Should I use a Battery or Hardwired Smoke Detector?

Battery detectors remain the most common forms of detectors because they are cheap and portable. They are usually operated by a battery you can buy at your local supermarket, making regular replacement possible.

Hardwired detectors give the added peace of mind that they are less likely to fail due to a dead battery. They usually have a backup battery, though, so no matter which type you choose, it is recommended that you check your batteries regularly.

Unfortunately hardwired detectors are expensive to install, so battery powered detectors remain the most common type. They are usually acceptable to use so long as you follow the instructions of your manufacturer, your local laws, and you check the batteries monthly.

Tip: If you can, buy smart detectors that are interconnected. When one detector identifies a fire, all alarms around the house will go off to alert your whole family instantly.

6. How often Should I Check my Smoke Detector?

First and foremost, follow your manufacturer’s instructions.

As a rule of thumb, smoke detectors should be checked about once per month to ensure they are functioning. Most detectors have a test button to allow you to test to see if the alarm will still operate.

Replaceable battery powered detectors may warn you when the battery is low via intermittent beeping.

Other detectors flash a light at regular intervals to show they are functioning.

Even if your battery appears to be functioning, it is good practice to replace batteries once per year. A good rule of thumb is to replace batteries every Christmas.

The exception is for alarms with non-replaceable 10-year batteries. If the alarm chirps to tell you this 10-year battery is running low, replace the full detector.

Always follow the rules in your jurisdiction and the alarm’s instructions.

Final Thoughts

Smoke detector placement is very serious. That’s why it’s important to follow the NFPA’s guidelines if they are the authority in your jurisdiction – if you live outside of the USA, you may have other guidelines to follow. We have done our best to provide the most accurate information, but it’s important you check the most up to date information as rules can change regularly.

This article has shared our opinions and a range of example circumstances, and is based on our online research. It does not constitute advice, professional or otherwise. Your circumstances or experiences will differ from ours. Make sure you do your own research and due diligence and adhere to the rules laid out in our terms and conditions and disclaimer.

Further Reading

  1. https://www.nfpa.org/-/media/Files/Public-Education/By-topic/Smoke-alarms/Smoke-Alarm-Installation-Guide.pdf
  2. https://www.nfpa.org/Public-Education/Staying-safe/Safety-equipment/Smoke-alarms/Installing-and-maintaining-smoke-alarms
  3. https://www.safety.com/smoke-detector-placement/