Can You Put a Cat Flap in Double Glazing? Here's How It Works (UK)

Yes, where the pane size, frame and flap requirements are suitable. Existing glass cannot be cut. The correct route is a new toughened double-glazed sealed unit made with the cat-flap aperture prepared before toughening.

We replace the sealed unit, not just one pane of an existing double-glazed assembly. The door frame can remain where suitable. The selected flap and adaptor must be confirmed before the glass is ordered.

The existing sealed unit is not suitable for an on-site cat-flap cut. Toughened glass cannot be cut or drilled after toughening, and an opening through a double-glazed assembly also requires the appropriate sealed construction around that aperture.

Don't try to drill, score or enlarge the pane, and don't rely on a special blade or drill-bit claim. A replacement toughened unit is manufactured for the selected flap. If the glass already has a hole, check whether a compatible adaptor and model can use it without altering the glass.

1. Check the flap and position. Confirm the exact model, adaptor, access on both sides and door movement.
2. Survey the glazing. Measure the sealed unit, its thickness and specification, and the required clearances.
3. Order the new unit. The opening is prepared before the glass is toughened, and the replacement sealed unit is manufactured around it.
4. Replace and fit. The old sealed unit is removed from the frame; the new unit and correct flap accessories are installed and checked.

The glass specification, manufacturing timescale and fitting arrangements are confirmed for the actual job. Don't order from visible glass measurements alone.

Choose by cat access needs and exact installation dimensions.

• Pet-Tek: compare the correct glass-compatible model and pet size.
• SureFlap: standard chip-controlled entry, larger Pet Door or individual-exit options depending on model.
• PetSafe: microchip models require the appropriate glass installation adaptor.
• Closer Pets: check the specific model's glazing accessories.
• OnlyCat: camera-based prey detection adds power and cable-route checks.

For the standard SureFlap Microchip Cat Flap, UK support specifies an optimum 212 mm circular glass opening with the correct adaptor. OnlyCat's glass guide also specifies 212 mm for a new opening, but that doesn't make every accessory or installation requirement interchangeable. Always use the selected model's current instructions. SureFlap UK support; OnlyCat glass guide.

Prices vary depending on door type, cat flap choice and location. Panel size, glazing specification, the model, mounting accessories and the condition of the frame all affect the total.

Ask the quote to state whether it includes the device, adaptor, new sealed unit, fitting and any disposal arrangements. We can install a flap you have already purchased.

Request a personalised quote with door photos, your postcode and the flap you want. An online estimate isn't a confirmed price for a measured glass unit.

Door-supplier and glass-manufacturer terms vary. If your door is under a guarantee, ask the supplier about its requirements for a replacement sealed unit before booking. We do not promise that every existing warranty is unchanged.

Our 3-year workmanship guarantee covers installation workmanship under its own terms; it is separate from the flap manufacturer's product warranty and any glazing warranty. See our guarantee page and raise any supplier requirements when you request a quote.

There are two stages: survey and glass manufacture, then installation once the unit is ready. It is not normally an immediate cut-and-fit visit because the glass is made for the chosen model.

Lead time depends on the specification, supplier and fitting availability. Tell us if you have a moving date or another deadline so the expected timescale can be confirmed before booking.

Send a clear photo of both sides of the door or window, your postcode, the model and whether you already own it. Show any existing flap, nearby step and whether the door slides or folds. For a powered model, include the nearest socket.

We assess glazing dimensions and movement clearances before ordering a new panel. A window installation also needs a usable approach and landing on both sides.

See our glass fitting service, coverage areas or microchip buying guide. Request your quote when you're ready.