Smoke alarm keeps chirping

Q: Smoke alarm keeps chirping

In Canada, a smoke alarm that chirps once every 30 to 60 seconds is almost always telling you its battery is low — replace the battery (even on hardwired units, which have a backup battery). If a fresh battery doesn't stop it, the alarm has likely reached its end of life: smoke alarms expire about 10 years after their manufacture date and must be replaced. A steady, loud alarm — not an intermittent chirp — together with any smoke, heat, or fire means get everyone out and call 911.

That single chirp every minute or so is annoying, but it's almost never smoke — it's the alarm asking for attention, usually a battery.

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Select anything that matches and the checklist below reorders to fit. Not sure? Skip it.

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In Canada, replace the battery first — a chirp every 30–60 seconds is the classic low-battery signal. Use the exact battery type printed on the alarm; on a hardwired unit, change the backup battery. This clears the chirp the vast majority of the time.

Ranked from real-world failure data. The order updates as you select what you’re noticing above.

Likely causes, in the order to check them

Showing the typical order

Beginner-friendly Doable, with care Safety-critical Call a pro

handymanHow to fix it

Replace the battery with the exact type printed on the alarm (or the backup battery on a hardwired unit), reseat it fully, close the drawer, and press Test to confirm.

Twist the alarm off its mounting bracket and open the battery compartment.
Fit a fresh battery of the exact type marked on the alarm; on a hardwired unit this is the backup battery behind the cover.
Close the drawer until it clicks, remount the alarm, and hold the Test button until it sounds to confirm it's working.

schedule5 min savings$4–12

Smoke-alarm batteryMatch the exact type printed on your alarm (often 9V or the specified lithium cell)

gavel Check your province first AB: homeowner may do this · BC: homeowner may do this · ON: homeowner may do this · PE: homeowner may do this · QC: homeowner may do this
Replacing an alarm battery is routine homeowner maintenance everywhere. Note: replacing a hardwired interconnected alarm involves house wiring, which varies by province.

visibilityHow to check

Take the alarm off its bracket (twist to release) and look on the back for a "manufactured" or "replace by" date.
If it's about 10 years past the manufacture date — or there's no date at all — it's at end of life and should be replaced, not repaired.
Replace it with a current alarm (consider a 10-year sealed-battery model), and replace other alarms of the same age at the same time.

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Why the list is in this order

We don’t sort by likelihood alone. We sort the way a good, honest tradesperson thinks: rule out the free, safe, common causes first. That’s why the cheap checks outrank the expensive repairs — and why anything dangerous gets a hard stop instead of a pep talk. The order exists to save you money, not to sell you anything.