What Is the Building Code for a Bathroom Smoke Alarm?

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There is a building code for a bathroom smoke alarm.
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Unless you want your hot shower or relaxing soak in the tub to have an extremely loud, monotonous soundtrack, it is probably best you do not put a smoke alarm in your bathroom. The steam from a hot shower or bath can trigger the alarm, and the moisture in the room can damage the alarm, rendering it useless. Most state building codes recommend not installing a smoke alarm in or near a bathroom, but if you really want one, you should follow certain guidelines.



It's best to install smoke alarms at least 3 feet outside of a bathroom since the moisture and humidity can cause the alarm to sound. Smoke alarms used near a bathroom should be the photoelectric type and have a silencing feature.

Bathroom Smoke Alarm Guidelines

To avoid nuisance alarms and malfunctions, do not install your smoke alarm in very damp, humid or steamy parts of your home, including bathrooms. Keep alarms a minimum of 3 feet away from bathrooms with tubs or showers. A smoke alarm located within 20 feet of a bathroom should be the photoelectric type. Choose an alarm with a silencing feature to let you stop nuisance alarms quickly and easily.

Properties of Photoelectric Smoke Alarms

Photoelectric smoke alarms are not common, but they are a good choice for installations near bathrooms. This type of smoke alarm consists of a light emitting diode and light-sensitive sensor inside a sensing chamber. The sensors on a photoelectric smoke alarm are faster to detect smoldering fires that generate large amounts of smoke.


On the other hand, the sensors in the more common ionization smoke alarms detect faster-burning fires with large flames. They have two metal plates and a small amount of radioactive material to ionize air. When smoke travels through the device, it disturbs the ionization and sets off the alarm. A dual alarm, which contains both ionization and photoelectric technologies, is also an option.

Other Smoke Alarm Requirements

While state building codes and manufacturers' guidelines advise against installing smoke alarms in bathrooms, they provide general rules and stipulations for other rooms. All dwelling units, hotels, motels, lodges and guest rooms must have smoke detectors that sound an alarm that you can hear in all sleeping areas. Smoke alarms are mandatory in new construction buildings and homes, when you add more sleeping rooms to existing residential buildings and whenever an addition or alteration to a house requires a building permit.


Smoke alarms should be in or near bedrooms and on each floor, including basements and habitable attics. Additionally, smoke alarms should be at least 20 feet away from cooking appliances and 3 feet away from air supply registers and ceiling fans with paddles. Placing them too close to these things can affect their functionality.

Smoke Alarm Maintenance

To keep your smoke alarm from beeping, keep all smoke alarms clear of dust and insects. Just like steam and moisture from the bathroom, dust and insects can cause the alarm to sound when there's no fire. Most manufacturers advise testing your smoke alarms every week and cleaning them every month.


If the smoke alarm unit is battery-operated or hardwired with a battery back-up, replace the batteries at least once a year. It is good practice to replace the entire smoke alarm unit every 10 years.



Claire has been writing and editing for 18 years. She has written for many digital publications, including Apartment Therapy, Good Housekeeping, Buzzfeed and Architectural Digest.