Which cat flaps can be installed in double glazing glass in UPVC doors?
Cat Flaps for Glass Doors & Double Glazing
Yes, a cat flap can be fitted into a glass door, double-glazed door or suitable glazed panel. However, if the existing glass is toughened or forms part of a sealed double-glazed unit, it normally cannot simply be cut to accept a cat flap.
In most modern doors, the usual solution is to have a new glass unit manufactured with the correct hole already cut into the glass. The cat flap or glass mounting adaptor is then fitted into this prepared opening.
At CatFlaps.co.uk, we supply glass-fitting cat flaps, microchip cat flaps, glass mounting adaptors and larger pet doors suitable for selected glass installations.
Can You Put a Cat Flap in a Glass Door?
Yes, but the installation method depends on the type of glass.
Older single glazing may sometimes be suitable for cutting by a professional glazier. Most modern external doors, however, use toughened safety glass, laminated glass or sealed double-glazed units.
Toughened glass cannot normally be cut after it has been manufactured. Attempting to cut it can cause the entire pane to shatter.
For this reason, a replacement glass unit is normally manufactured with a circular opening specifically sized and positioned for the chosen cat flap.
Cat Flaps in Double Glazed Doors – The Short Answer
- Existing toughened glass: Normally cannot be cut after manufacture.
- Double glazing: Usually requires a replacement sealed unit manufactured with a pre-cut hole.
- Single glazing: Some types may be suitable for professional cutting.
- Microchip cat flaps: Often require a compatible glass mounting adaptor.
- Sliding patio doors: Cat flap installation is possible, but replacing a large glass unit can be more expensive.
How Is a Cat Flap Fitted into Double Glazing?
- Choose the cat flap you want to install.
- Check whether a glass mounting adaptor is required.
- Confirm the manufacturer's required glass hole diameter.
- Have the existing glass unit professionally measured.
- Order a new sealed glass unit manufactured with the correct hole.
- Replace the existing glass with the new prepared unit.
- Install the cat flap and adaptor into the circular opening.
Choose the cat flap before ordering the glass. Different cat flaps and glass adaptors require different diameter holes, and this cannot easily be changed after the new toughened glass has been manufactured.
What Size Hole Is Needed for a Cat Flap in Glass?
There is no universal cat flap glass hole size. The required diameter depends on the particular cat flap and whether a glass mounting adaptor is being used.
Some manual cat flaps are designed around relatively small circular openings, while electronic and microchip models may use a larger mounting adaptor.
Never guess the glass hole diameter. Check the installation instructions for the exact cat flap and adaptor before ordering your replacement glass.
Microchip Cat Flaps for Glass Doors
Microchip cat flaps are an excellent choice for glass doors when you want to give your own cat access while helping prevent neighbouring cats and other unwanted animals from entering your home.
The cat flap reads your cat's registered microchip and unlocks when an authorised pet approaches.
Many microchip cat flaps require a glass mounting adaptor when installed into glass. The adaptor provides the appropriate mounting surface around the circular opening and can also improve the finished appearance of the installation.
Manual Cat Flaps for Glass
Manual cat flaps provide a simpler option when selective electronic entry isn't required.
Many manual models provide 4-way locking, allowing you to select:
- Free access in and out
- Entry only
- Exit only
- Fully locked
Check that the particular model is suitable for glass fitting before ordering your replacement glass unit.
Large Cat Flaps & Small Dog Doors in Glass
Some large cat flaps and pet doors can also be fitted into suitable glass installations, providing access for bigger cats and some small dogs.
The important consideration is not only the pet opening size but also the diameter of the hole required through the glass.
Larger pet doors aren't automatically suitable for glass. Many conventional dog doors require rectangular cut-outs rather than circular holes, making them unsuitable for normal toughened-glass installations.
Can You Fit a Cat Flap into a Patio Door?
Yes. A cat flap can be fitted into many glazed patio doors, including suitable sliding and hinged doors.
If the existing panel is toughened or double glazed, it will normally need to be replaced with a new glass unit manufactured with the required circular opening.
Because patio doors can contain considerably larger panes of glass than conventional doors, the cost of replacement glass may be higher.
Cat Flaps in French Doors & Conservatory Doors
The same principle applies to many glazed French doors, conservatory doors and glazed uPVC doors.
If there is a suitable glass panel, a replacement unit can potentially be manufactured with a correctly positioned hole for a compatible cat flap.
The available space around the hole is important. The cat flap and any mounting adaptor must sit comfortably within the glass without interfering with the glazing beads or door frame.
Cat Flaps in Double Glazed Windows
Depending on the location and suitability of the window, some glass-fitting cat flaps can also be installed into a double-glazed window unit.
As with a glazed door, the existing sealed unit would normally be replaced by a new unit manufactured with the correct circular opening.
Double Glazing Thickness
Double-glazed sealed units are manufactured in different thicknesses. Common configurations include approximately:
- 20mm
- 24mm
- 28mm
Other thicknesses are also widely used, and triple-glazed units can be substantially thicker.
Don't assume the thickness from the age or appearance of your door. The existing unit should be properly measured before replacement glass is ordered.
Alternative Option – Replace Glass with a uPVC Panel
If your door has a separate lower glazed panel, another possibility is to replace that section with a suitable uPVC door panel and install the cat flap into the new panel.
This can sometimes provide a simpler alternative to manufacturing replacement glass, particularly where the existing glazed panel is very large.
Whether this is practical depends on the construction and design of your particular door.
Before Ordering a Cat Flap for Glass
- Identify the type of glass in your door.
- Choose the cat flap before ordering replacement glass.
- Check whether the cat flap requires a glass adaptor.
- Confirm the exact required hole diameter.
- Have the glass professionally measured.
- Check the thickness of the existing sealed unit.
- Check there is sufficient clearance around the proposed hole.
- Make sure the cat flap will be positioned at a comfortable height for your cat.
Professional Glass Installation
We recommend using an experienced glazier or glazing installer to measure and replace toughened or double-glazed units.
The installer can check the existing glass specification, unit thickness and available space before a replacement panel is manufactured.
If you're unsure which cat flap to choose, speak to us before the glass is ordered. It is much easier to confirm the correct cat flap and hole diameter before the replacement unit goes into production.
Frequently Asked Questions
Can you put a cat flap in a glass door?
Yes. Cat flaps can be installed into suitable glass doors, but toughened and double-glazed glass will normally require a new glass unit manufactured with the correct hole.
Can existing double glazing be cut for a cat flap?
Usually not. Most modern double-glazed doors contain toughened safety glass which cannot normally be cut after manufacture. A replacement sealed unit with a pre-cut hole is generally required.
Do I need a special cat flap for glass?
You need a cat flap that is suitable for glass installation. Some models fit directly into an appropriate circular opening, while others require a compatible glass mounting adaptor.
Can a microchip cat flap go in glass?
Yes. Many microchip cat flaps can be installed into glass when used with the appropriate mounting adaptor and correctly sized glass opening.
Do I need to buy the cat flap before ordering the glass?
Yes, this is strongly recommended. You need to know the exact model and any adaptor being used so the glass manufacturer can produce the correct hole diameter.
What size hole is needed for a cat flap in glass?
The required diameter varies between models. Always use the manufacturer's specification for the exact cat flap and mounting adaptor you intend to install.
Can a cat flap be fitted into a sliding patio door?
Yes, subject to the construction of the door. If it contains toughened or double-glazed glass, the existing unit will normally need to be replaced with a new panel manufactured with the appropriate hole.
Can I put a cat flap in a double-glazed French door?
Potentially, yes. A suitable replacement sealed glass unit can be manufactured with a hole for a compatible cat flap, provided there is sufficient space within the glazed panel.
Is a uPVC panel easier than glass?
It can be. If the design of the door allows a lower glass section to be replaced with a suitable uPVC panel, fitting a cat flap into the panel can sometimes provide a simpler alternative to replacing a large glass unit.
Shop Cat Flaps for Glass Doors & Double Glazing
Browse our range of cat flaps for glass doors, microchip cat flaps, manual cat flaps and glass mounting adaptors below.
If you're planning a new double-glazed unit and aren't sure which product you need, contact CatFlaps.co.uk before ordering your glass. We can help you identify the appropriate cat flap, adaptor and required glass hole size.
