Pet flaps
Can You Fit a Cat Flap in a Glass Door?
Yes, but not by cutting the glass yourself. How cat flaps go into glass and uPVC doors, what to choose for a microchipped cat, and what to check first.
(updated ) · Handyman Manchester
Yes, you can have a cat flap in a glass door. You cannot cut the hole yourself, and it is not done by drilling the existing pane. The glass has to be made or replaced with the hole already in it.
Why you cannot cut the glass
PetSafe says it is not possible to cut holes in tempered or double-pane glass, except at the time of manufacture. It says cutting glass is a skilled job for a professional glazier or glass manufacturer. A specialist retailer says the same about toughened safety glass: it cannot be cut after it has been manufactured and toughened, and the answer is a replacement sealed unit made with the opening.
How it is done in a uPVC or glass door
The usual route is a replacement glass unit with the opening already cut for the flap. The flap goes into the new unit, and the unit goes back into the door. That is why glass replacement is part of our cat flap installation service. Double glazing normally needs a flap with the right adaptor for the thickness of the unit.
Older homes can be trickier. One customer called us about a Georgian wired-glass door and a fitter arrived within an hour. Wired glass, leaded glass and original features all need care, so send a photo of the door and we will tell you what is possible.
Timber and steel doors
Timber is the simplest. The installer marks the opening, cuts it, fits the frame and seals it. Steel and security-screen doors need the right tools and a neat finish so the flap does not weaken the door. We fit both.
Choosing a flap
The RSPCA says a cat flap lets your cat come and go, and that a microchip version means only your cat will come in. Cats Protection says microchip or magnetic flaps give your cat security, so neighbouring cats do not enter your home. GOV.UK says cat microchipping became mandatory on 10 June 2024, with cats chipped before they reach 20 weeks. Check that the flap you choose works with your cat's chip.
- Measure your cat, then check the flap's opening size against the cat's height and width.
- Decide who you want to keep out: other cats (microchip or magnetic flaps), or only draughts (a well-sealed standard flap).
- Check the flap suits the thickness of your door or glass unit.
What it costs
The price has three parts: the flap, the glass unit made to fit, and the fitting. The glass unit depends on the size and type of glazing, so we quote after seeing a photo. For the flap alone, catflaps.co.uk listed a PetSafe microchip flap with a glass adapter at £97.20 on 24 September 2026. We quote one fixed price for the whole job.
What we fit and what is covered
We fit cat and dog flaps from a range of brands, including Staywell, in timber, glass, uPVC, steel panels and security screens. Every installation comes with a 12-month manufacturer's warranty. We cover the North of England and Wales.
Send a photo of your door and the type of flap you want to get a fixed price.