The alarm keeps going off at night

Get the activation log from your monitoring company before touching anything. Date, time and zone for every activation over the last few months.

That list is the diagnosis. Repeated activations clustering on one zone point at one opening, and repeated activations across many zones point at something else entirely.

Why the door is usually the answer

A door contact reports when the door and the magnet separate. It has no opinion about why. A door that latches properly cannot separate, and a door that is resting against its frame rather than latched can move enough to break the contact under wind load or building pressure.

The fault therefore sits with the latch rather than the alarm, and replacing a contact rarely fixes it. Our article on a door that will not close or latch covers the causes, and alignment covers the repair.

Read the pattern before you walk the building

One zone repeatedly: that opening. Check it first and check it properly.

Several door zones on the same elevation: building pressure or wind, which is usually the air handling running at night or a door elsewhere that has been left open and changed the pressure across the building.

Always around the same time: something scheduled. Air conditioning starting, irrigation, a timeclock, a cleaner, a delivery, an automatic gate cycling.

Motion zones rather than door zones: something moving inside. Blinds or signage moving in front of a detector when air conditioning starts is the classic. Also balloons, hanging displays, and insects on a lens.

Scattered and increasing over months: batteries in wireless devices, which is genuinely an alarm company matter.

The checks worth doing at the door

Open it halfway and let go. It has to close and latch on its own without help. A door that needs a push or a pull the last part of the way is the fault, whatever else is going on.

Look at the strike plate for a bright wear mark above or below the opening, which shows exactly how far the door has dropped. Check whether the contact and its magnet still line up, since a dropped door moves the contact as well as the latch.

Check the closer is still doing its job and has not been wound down by somebody who found the door hard to open. Check the weatherstripping has not hardened enough to hold the door off its keeper. On a gate, check the track, the rollers and whether it is seating in its latch at all.

Why this is worth fixing rather than living with

Repeated false activations carry costs that build quietly. Many jurisdictions charge for repeated police response and some withdraw it. Whoever holds the keys stops attending promptly, and after a few weeks nobody treats an activation as real.

That last one is the actual risk. A building where the alarm goes off twice a week is a building where a genuine break-in gets a delayed response from somebody who assumes it is the same door again.

The door fault is also a security fault in its own right. A door that does not latch reliably is a door that does not lock reliably, which is a separate problem the alarm happens to be reporting for you. Our article on a door that will not lock covers that side.

The split between the two vendors

The panel, the detectors, the contacts, the wiring and the monitoring belong to your alarm company. Batteries, sensitivity, zone programming and device faults are theirs and we do not work on them.

Doors, frames, strikes, closers, hinges, alignment, locks, exit devices and gates are performed directly by our own technicians. On a repeated false alarm, that is where the cause usually sits.

Neither vendor is usually given the whole picture. Send the activation log to whoever is looking at the doors, and tell your alarm company what was found at the door. Two visits that do not know about each other is how these run for months.

Closing it out

Once the door is corrected, keep watching the log for a few weeks rather than assuming. Buildings with one bad door often have two, and the second only becomes visible once the first stops dominating the report.

Add a latch check to the closing routine, which takes seconds per door and catches this before the alarm does. Our closing checklist covers what that looks like in practice.