How long does a smoke alarm last?
Typical
10 years
Range
8–10 years
The whole smoke alarm — not just the battery — must be replaced every 10 years: the sensor degrades regardless of battery state, and every unit carries a printed expiry or manufacture date. Sealed 10-year-battery models make the schedule honest.
What decides it
- The printed replace-by date on the unit is the rule — check it today
- Monthly test button press; vacuum the vents yearly
- Rented homes: alarms on every storey are a legal requirement in England and Scotland
When to replace rather than repair
There is no repair — at 10 years (or the printed date) it’s a replacement, no exceptions.
Typical ranges from manufacturer guidance and industry surveys — individual machines vary with use and care. General information, not advice on a specific appliance.