Replace at ten years
NFPA and CPSC guidance says to replace smoke alarms when they are ten years old. The date is usually printed on the back, which may require safely removing the unit from its mounting ring.
Replace sooner when necessary
A unit that fails its test, is damaged, has been painted, repeatedly faults after proper maintenance or is subject to a manufacturer recall should not be treated as good merely because it is under ten years old. Follow the manufacturer’s instructions.
Yellowing is a cue, not a date
Discoloration can be a useful visual clue that an alarm is old, but it is not a calibrated expiration test. Read the label and assess the condition of the entire set.
Record the new date
When replacements are installed, record the installation and replace-by dates in a household file. Keeping the alarms on one understandable schedule makes the next maintenance cycle far easier.
Safety references
Primary sources used for this page:
Manufacturer instructions and current local requirements control. For an emergency, call 911.