Inside every bedroom, and outside each sleeping area. On every level of the home, basement included. On the ceiling or high on a wall; the manufacturer's instructions give the exact spot. Ideally interconnected, so that when one sounds they all do. Hardwired alarms, the kind running off the home's electrics, should only be installed by a qualified electrician.

Smoke alarms at home: where they go, what to buy, and when to replace them

A monthly test, a yearly battery and a new unit at ten years, plus the right response if cooking sets one off, per the U.S. Fire Administration.

19 October 2026 How To 2 min read

A smoke alarm with a dead or missing battery, the U.S. Fire Administration says, is the same as having no alarm at all. And once one sounds, a household may have less than two minutes to get out. A cheap device, then, but only if it is in the right place and working.

Where to fit them

Inside every bedroom, and outside each sleeping area.
On every level of the home, basement included.
On the ceiling or high on a wall; the manufacturer’s instructions give the exact spot.
Ideally interconnected, so that when one sounds they all do.

Hardwired alarms, the kind running off the home’s electrics, should only be installed by a qualified electrician.

Which type

There are two sensor types, ionization and photoelectric, and each picks up a different kind of fire. Since nobody can predict which fire might start, the agency recommends having both, or dual-sensor alarms that combine them. Alarms that flash or vibrate exist for people with hearing loss.

Upkeep by power source

9-volt battery: test monthly, replace the battery at least once a year, replace the whole alarm every 10 years.
Sealed 10-year lithium battery: test monthly, replace the alarm as the manufacturer instructs.
Hardwired: test monthly, replace the backup battery at least yearly, replace the unit every 10 years.

The ten years run from the manufacture date, not the day it went up.

When it goes off over the stove

Do not pull the battery. Open a window or door and press the hush button, then wave a towel at the alarm to clear the air. If kitchen or shower steam keeps setting it off, move the whole alarm a few feet further away. Disabling an alarm, in the agency’s words, can be a deadly mistake.

Photo: A smoke detector on a ceiling. By Georg Pik, CC0, via Wikimedia Commons.

Source: U.S. Fire Administration, “Smoke Alarms”, usfa.fema.gov, read 18 October 2026.