Smoke Alarms: When to Test, Replace and What to Buy

Smoke alarms should be tested once a month and replaced 10 years after the date they were made. That date is printed on the back of each alarm. Many homes have alarms older than that and nobody has looked.

Heating season is a good time to check, since furnaces, space heaters and holiday cooking all run more. Here is how to check what you have and buy the right replacements once.

Key takeaways

• Press the test button on every alarm, once a month.
• Look at the date on the back. Replace any alarm made more than 10 years ago.
• You need one inside each bedroom, one outside each sleeping area, and one on every level.

How do I know if my smoke alarm is too old?

1. Take it down and look at the back. Most alarms twist off the ceiling plate. The manufacture date is printed on the label. Fire safety groups including NFPA and the U.S. Fire Administration say to replace alarms 10 years after that date.
2. Treat a missing date as too old. If there is no date, or you cannot read it, replace it.
3. Listen for a chirp. A short chirp every minute or so usually means a low battery. Some newer alarms also chirp at end of life. Check the label to see which.
4. Write the date on the new one. Use a marker on the base. Next time you will not need to take it down.

Where should smoke alarms go?

The U.S. Fire Administration and the Consumer Product Safety Commission give the same three places:

• Inside every bedroom.
• Outside each sleeping area, such as the hallway by the bedrooms.
• On every level, including the basement.

Keep them at least 10 feet from the stove so cooking does not set them off. An alarm that keeps going off during dinner is the one people pull down and forget to put back.

What kind of smoke alarm should I buy?

You do not need the most expensive model. You need the right features.

1. A 10 year sealed battery. These alarms never need a battery change. You replace the whole unit when it reaches 10 years. It removes the most common reason alarms stop working.
2. Interconnected alarms. When one sounds, they all sound. Fire safety groups recommend this, because you may not hear an alarm at the other end of the house. Some connect by wire, others wirelessly.
3. A testing lab listing. Look for a mark from a recognized testing lab, such as UL, on the box.
4. Match what you already have if it is hardwired. Alarms wired into the house usually need the same brand, or an adapter, to fit the existing plate. Read the old one's label before you shop.
5. Compare per alarm, not per box. Multipacks are common. Divide the price by the number of alarms, as the unit price shelf tag does. Check current price before you buy.

Mistakes that leave you unprotected

• Taking out the battery to stop a chirp. Replace it the same day instead.
• Painting over an alarm. Paint can block the sensor.
• Testing only one alarm. Each one can fail on its own.
• Forgetting the backup battery. A hardwired alarm still has one. Change it about once a year.
• Ignoring carbon monoxide. If you have gas heat, a gas stove or an attached garage, you also need CO alarms. They are a separate device unless the box says combination.

If you are adding a space heater this winter, read space heater safety checks first. The furnace filter guide covers the other heating season job worth doing the same day.

Quick action checklist

• [ ] Count your bedrooms, hallways and levels. That is how many alarms you need.
• [ ] Take each alarm down and read the date on the back.
• [ ] Replace any alarm over 10 years old, or with no date.
• [ ] Press test on every alarm and set a monthly reminder.
• [ ] Write the install date on each new alarm in marker.

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Follow the instructions that come with your alarm and your local fire code. Check current price before you buy. See our disclosure policy for details.