Smoke Alarms – A Home Inspector’s Perspective

by Feb 21, 2020

During a home inspection, a home inspector observes 300 to 500 items or more. Under certain conditions, the home inspector will find many of those items to be unsafe. For example, things like electrical and HVAC systems and kitchen and laundry appliances can start a fire. Should a fire start, the building’s smoke alarms should warn the occupants. In this post, I’ll offer my perspective on smoke alarms – NOT smoke detectors. THEY ARE NOT THE SAME.

A detector has a built-in smoke sensor. If the device detects smoke, it sends a signal to a control panel that triggers an external siren, strobe light, or other warning system. Typically, you’ll find smoke detectors in condo buildings, hotels and commercial buildings.

Smoke alarms are self-contained smoke sensing devices. They include a built-in power supply and alarm. With few exceptions you will find smoke alarms in single- and multi-family residences.

Types of Smoke Alarms

Manufacturers offer variations on two basic types of smoke alarm: ionization and photoelectric. You’ll find both types in hard-wired, battery-operated, plug-in, wireless, or combination versions.

What’s the difference?

Ionization Alarms were developed in the 1970s. They notoriously go off when you’re cooking or showering. They work well for blazing fires, but not so well with smoldering smoke.

Photoelectric Alarms are good for smoldering fires, but not so good with blazing fires.

So which one should you chose?

That is a great question. The National Fire Prevention Association (NFPA) recommends using both types. If you have to choose, I recommend photoelectric smoke alarms. Smoke – not fire – causes most fire-related deaths in the US. Usually, you can find the type of alarm printed on the back of the device. If you don’t seen the type listed, you can presume it is ionization.

History of Smoke Alarms

The Illinois Smoke Detector Act took effect on January 1, 1988. The act applied to new construction and existing structures. It required single-family and multi-family residences and hotels to have an approved, operational smoke alarm on every floor. This included basements but excluded crawl spaces and non-occupied attics. Smoke alarms also had to be placed within 15 feet of any room used for sleeping. New construction had to have hardwired alarms.If there were two or more alarms, they had to be interconnected. Existing buildings could have battery-operated, plug-in, or hardwired alarms.

At some point, municipalities also added code requirements stating that new construction or renovated houses had to have smoke detectors inside every room used for sleeping. In 2011, they amended the act for new construction. All the requirements remained the same except that you had to have a battery or generator back up.

Inoperative Smoke Alarms

In a 2019 NFPA report, Smoke Alarms in U.S. Home Fires. nearly 43% of the homes involved in fires had smoke alarms with missing or disconnected batteries. Dead batteries caused 25% of smoke alarm failures. Statistics like these drove manufactures to improve battery technology.

This new battery technology spurred another amendment, which will take effect January 1, 2023. At that point, every single-family, multi-family, and hotel structure will have to replace removable battery alarms (non-hardwired alarms) with 10-year, sealed battery smoke alarms. Hardwired or wireless alarms with removal batteries will be excluded.

Testing and Replacing Alarms

Manufacturers recommend that alarms be tested every month by pressing the test button. The problem is that this only tests the battery and alarm. It gives you a false sense of security because it does not test the smoke sensor. You can use a UL approved can of smoke to test the smoke sensor. I have known people to use a match for testing, but some manufacturers don’t recommend it.

Manufacturers usually recommend that you replace your smoke alarms when they’re 10 years old. The smoke sensors are considered to be unreliable after that point. Since there is no date on your alarm, presume it is more than 10 years old and replace it. If the smoke alarm’s casing has a yellowish hue, it’s likely that the alarm is around 10 years old. Best practice? Replace the alarm with one from the same manufacturer. The quick connect wiring harness will match and connect easily.

When you replace your smoke alarms, throw photoelectric alarms out with your regular garbage. However, ionization alarms contain very minute radioactive particles. Your best bet: contact the alarm’s manufacturer to see whether it will take it back for recycling. You can also contact your local city or county to find a hazmat disposal location.

False Alarms

False alarms have a variety of causes. Most most of the time the problem is the alarm’s location. If you locate your smoke alarm near your stove, shower, or a window, particles from cooking food, humidity, or steam can set off the alarm. Other reasons include insect intrusion or dust. In these cases, follow the manufacturer’s maintenance and cleaning instructions.


Smoke alarms save lives. Make sure you install them correctly and keep them in proper working order. It’s one of the best things you can do to keep your family and home safe from fires.

In my next post, I’ll give you a home inspector’s perspective on a similar device – a carbon monoxide detector. Follow us on Facebook to get notified about new blog posts and other 3-D Home Inspection happenings.

Monthly Archives

Get more information or schedule your inspection today!