An alarm that keeps sounding for no apparent reason is a problem with a cause, and the cause is almost always findable. It is worth finding because the alternative people reach for, taking the battery out or covering the detector, converts a nuisance into an unprotected building, and that decision is made in irritation rather than on the evidence.
The common causes in a home
Steam from a bathroom or a kettle reaching a nearby alarm. Dust from building work or from a loft. Insects inside the sensing chamber, which is more common than people expect. Cooking reaching a smoke alarm sited too close to the kitchen. An alarm at the end of its service life, whose chamber has drifted. And a low battery, which usually chirps rather than sounds but is easy to misread at three in the morning.
The common causes in a workplace
Steam and dust again, plus aerosols, hot works, vehicle exhaust near a loading bay, and detectors sited under supply air diffusers where airflow carries anything past them. On an addressable system the panel names the device, so the pattern is visible in the event log immediately. On a conventional system the zone is the clue and the log book is the only record of where and when, which is why filling it in matters.
Finding yours
Write down every activation with the time, the device or zone, the weather and what was happening in the building. Three or four entries usually make the pattern obvious: always on a Monday, always when the kitchen extract is off, always in the hour after the cleaners finish. A pattern turns a mysterious fault into a specific conversation with an engineer about siting or detector type.
What to do instead of disabling it
Relocate the device, change the detector type for that space, or fit a type designed to discriminate between smoke and steam or dust. All three are ordinary work. If an alarm genuinely cannot be lived with while that is arranged, the honest interim is a recorded temporary arrangement with an alternative means of detection, not a detector in a plastic bag that everybody forgets about.
Questions people ask about why does my fire alarm keep going off
Why does my smoke alarm go off at night for no reason?
Falling overnight temperature can push a marginal battery below its threshold, which is why end of life and low battery chirps so often start in the small hours. An alarm past its service life is the other common cause.
Can insects set off a smoke alarm?
Yes, and it is a genuinely common cause. A small insect inside the sensing chamber scatters light exactly as smoke does. It is one reason alarms are cleaned as part of a maintenance regime.
Is it ever acceptable to disable a detector?
Only as a recorded temporary measure with an alternative arrangement in place, and with a date for the fix. A disabled detector that nobody wrote down is how buildings end up unprotected for years.