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How to fit a window alarm without drilling the glass

Updated: 16 October 2026

You have the packet in your hand and a pad that will either hold or peel off by morning. How to fit a window alarm, for this set, is clean, stick or align, arm, and test once. A puck goes on the inside of one pane. A contact needs two flat faces inside its own gap. You do not drill the sealed edge. The rows are on the [window alarm comparison](/hub/burglar-protection/window-alarm). This page is from the Products Compared editorial team, from the amazon.co.uk listings and public UK sources, not a lab fit. A qualifying purchase can earn a commission at no extra cost to you.

You have the packet in your hand and a pad that will either hold or peel off by morning. How to fit a window alarm, for this set, is clean, stick or align, arm, and test once. A puck goes on the inside of one pane.

Our top picks

TECKNET TECKNET window and door alarm, 3-pack

Best overall

TECKNET TECKNET window and door alarm, 3-pack
8.6/10about £13.99
View offer
VOXON VOXON magnetic window alarm, 4-pack

Preis-Tipp

VOXON VOXON magnetic window alarm, 4-pack
8.6/10about £12.74
View offer
WER WER Doberman slim window alarm, 2-pack

Alternative

WER WER Doberman slim window alarm, 2-pack
6.8/10about £15.97
View offer
On this page
  1. 1.Before you stick anything
  2. 2.Fit a vibration alarm on the glass
  3. 3.Fit a magnetic contact on a flat frame
  4. 4.Test it, then stop if the frame will not allow it

Before you stick anything

Lock the window first. Avon and Somerset Police put the fastening ahead of the alarm. Work on the inside face. Which? describes drilling a misted sealed unit as a moisture fix, not a mount. Do not screw these pucks into the glass. One piece uses the glass path. Two pieces use the contact path. Clean until the face is dry and free of grease. The listings name no solvent. NICE Home needs two AAA cells that are not in the box. TECKNET and WOWSEA do not clearly say the cells are included. A silent test on an empty unit is not a failed stick.

Fit a vibration alarm on the glass

Defender, Flintronic, WER and WOWSEA go on the inside of the pane you care about, clear of the gasket. One puck covers that pane only. WOWSEA’s listing prints both 70 × 8 × 70 mm and 7 × 0.8 × 0.8 cm, so do not invent a clearance. Defender, WER and WOWSEA are on and off. Flintronic says turn it on, wait five seconds for a beep, then the siren runs for 30 seconds. Test with one knock while you can reach the switch. Later sun trips belong on the window alarm false alarm page.
TECKNET TECKNET window and door alarm, 3-pack

Testsieger

TECKNET TECKNET window and door alarm, 3-pack
8.6/10about £13.99
View offer

Fit a magnetic contact on a flat frame

Put one half on the frame and one on the moving sash, arrows facing, so shut reads as shut. TECKNET alarms beyond 2 cm. VOXON alarms beyond 20 mm. Those gaps are not Ring’s 2.5 cm limit. The faces need to be flush. A bevelled edge stops TECKNET and NICE Home meeting. If they cannot sit flush, stop, and do not pack wedges. VOXON is one-sided, so a left-hand door may need the body upside down. This page does not add a pairing guide for Miangerrn. Why choose a contact is on the window alarm buying guide.

Test it, then stop if the frame will not allow it

A pass is one deliberate test. For a puck, one knock trips the siren and you switch it off, or on Flintronic you let the 30 seconds finish. For a contact, open the sash once and close it. TECKNET keeps going until the parts meet, so do not walk away with the window ajar. A fitter takes over for a police unique reference number, a failed lock or frame, a fit that seems to need a drill, or a neighbour dispute about noise. None of those is solved by a firmer press on the pad.

Common questions

Where do I stick a vibration window alarm?
Stick it to the inside of the pane you want to watch, on clean dry glass, clear of the gasket. One puck covers that pane only. Defender, WER and WOWSEA are on and off. Flintronic adds a five-second beep, then a siren of up to 30 seconds. Do not drill the sealed unit.
Do I put the magnet on the frame or on the moving sash?
One half on the frame, the other on the moving sash, arrows facing, so they meet when the window is shut and separate when it opens. A magnet in the middle of the glass never separates. NICE Home’s reviews add that the two faces need to be flush, not perched on a bevel. Follow the arrow printed on your own packet.
How close do the two magnetic parts need to be?
Use your listing. TECKNET says within 2 cm of the arrow side and alarms beyond 2 cm. VOXON alarms beyond 20 mm. Ring’s 2.5 cm figure is for Ring’s contact, not these units. If a curved edge cannot hold the halves that close, stop. Packing the gap with scraps is not the fix this set was reviewed against.
Can I drill a uPVC window to fit the alarm?
No. These are peel-and-stick alarms. Drilling the sealed edge of a double-glazed unit is a glazing problem, not a mount. Which? treats a hole in a misted unit as a short-term moisture fix. Screwing a shock sensor into the frame is practice for a different, wired device.
What should I clean the glass with before I stick the pad?
Make it dry and free of grease. The listings do not name a solvent or a primer, so this page does not invent one. Let a normal glass clean dry, then press the pad from the box. Silicone spray is a common reason a pad lets go overnight. If the cells are a separate purchase, as with NICE Home’s AAA batteries, fit them before you commit the adhesive.
When should a fitter take over?
When you need a monitored system and a police unique reference number, when the lock or frame has failed, or when the fit seems to need a drill into the glazing or the lock. A neighbour row about noise is the same stop. A curved edge that will not let a contact meet is a mismatch, not a job for a longer screw.

Related pages

Best window alarm

Vibration versus contact

Window alarms

Window alarm buying guide: sensor, frame and cells

Window alarm false alarm: sun, gap, and the noise rule

Sources

Public UK sources and the amazon.co.uk listings in this comparison. Listings checked 15 October 2026.

  1. Police.uk: keep burglars out of your property (retrieved 15 October 2026)
  2. ProtectUK: alarms and CCTV (retrieved 15 October 2026)
  3. nidirect: securing doors and windows (retrieved 15 October 2026)
  4. GOV.UK: how councils deal with noise complaints (retrieved 15 October 2026)
  5. Clean Neighbourhoods and Environment Act 2005, alarm powers (retrieved 15 October 2026)
  6. NSI: intruder alarm systems (retrieved 15 October 2026)
  7. NPSA: intrusion detection (retrieved 15 October 2026)
  8. Avon and Somerset Police: burglar alarms (retrieved 15 October 2026)