Most contact sensors have two parts: a sensor body and a magnet. The system detects whether those parts are close enough to count as closed. Correct alignment matters more than making both pieces look symmetrical. Follow the instructions for your exact model, especially on metal frames or recessed doors.
Before mounting
Pair the sensor near the hub, assign a location name, and open and close the two parts by hand to confirm a status change. Check the battery tab has been removed and that the hub receives the signal. Then take the sensor to its final location and repeat the test before attaching anything.
Choose a stable surface
Clean and dry the mounting area according to the adhesive instructions. Flaking paint, loose trim, dust, and textured surfaces can weaken a bond. If screws are recommended, make sure the mounting method is suitable for the frame and permitted by your lease. Do not drill into wiring, glass, or a surface you cannot identify safely.
Respect the specified gap
Manufacturers set a maximum gap and alignment marks for each model. Do not substitute a generic gap from an online video. Uneven trim may require an approved spacer. Check that opening the door will not strike or dislodge either part. Test with the door fully latched and with any weatherstripping compressed as it normally is.
Test the real entry routine
- Confirm the app shows closed when the door is securely shut.
- Open it slowly and verify the status changes.
- Close and latch it several times to check consistency.
- Use the alarm’s test mode to confirm the configured response.
- Check entry delay settings for doors used to arrive home.
A status notification is not proof that professional monitoring receives an alarm. Use the provider’s testing process if you have that service.
Recheck after installation
Adhesives can shift, doors can swell with weather, and batteries eventually weaken. If a sensor intermittently shows open, inspect alignment and the mounting surface before replacing the whole device. If the app reports offline rather than open, investigate battery and radio coverage instead.
Continue with our DIY alarm starter guide or learn how to reduce false alarms.
