Installing a cat flap in double glazing gives your cat independent access to the garden without leaving a door or window open.
Crystal installs cat flaps in double glazed doors across Burnley, Pendle, Blackburn and nearby towns and villages. Rather than altering the glass already fitted, we replace the existing sealed unit with a new one manufactured to include an accurately positioned hole for the chosen cat flap.
Can you install a cat flap on a glass door?
Yes. A cat flap can be fitted to most suitable double glazed doors while retaining the existing door and frame. Only the sealed glass unit needs to be changed.
A double glazed unit consists of two panes joined around a sealed spacer. Cutting into the completed unit would break this seal and compromise its insulating and weather-resistant properties. Door glazing is also generally made from toughened safety glass, which cannot be drilled or cut once it has been manufactured.
The existing glass is therefore measured and a new unit is produced with an aperture formed to the dimensions required by the cat flap. Once installed, the replacement unit provides a secure fixing point while maintaining the appearance, insulation and weather resistance of the door.
How do you fit a cat flap in a double glazed door?
The door and existing glazing are first inspected, and the chosen cat flap is checked to make sure it is suitable for installation through glass. Its aperture size and position must be confirmed before the replacement glazing unit is ordered.
The process normally involves:
- Measuring the existing sealed unit
- Checking the glass thickness and specification
- Choosing an appropriate cat flap
- Confirming the cat flap template
- Agreeing the height and position of the opening
- Manufacturing the replacement unit
- Removing the original glass
- Installing the new unit and fitting the cat flap
The aperture is formed during manufacture, before the panes are toughened and assembled. Correct positioning is important: the flap must sit at a comfortable height for the cat while leaving enough glass around the opening to maintain the strength of the unit (min. 100mm from the bottom of the panel).
Choosing a cat flap for a double glazed door
Not every cat flap is intended for use in glass. The model should therefore be selected before the replacement unit is ordered and its fitting instructions checked carefully.
Lockable versions allow access to be controlled, while microchip models recognise an authorised pet and can help prevent unfamiliar cats from entering the property.
When choosing a cat flap, consider:
- The size of your cat
- Whether controlled entry is required
- The aperture specified by the manufacturer
- The depth of the tunnel section
- Whether a glass adaptor is needed
- Access to batteries or electronic controls
We can help you choose a cat flap as our technicians are familiar with the many different brands and designs available.
The cat flap should be in your possession before final measurements are confirmed. Similar-looking products can require different openings, so the glass should not be ordered using an estimated size.
Will the replacement glass match the existing door?
The new unit can be made to closely match the glass already fitted in the door. Clear, patterned, obscure and coated glass may all be available, depending on the existing specification. An exact match may not always be possible where the original glass is old or discontinued. Modern glass may also have a slightly different tint or finish.
Any potential difference will be identified by our technician before the order is placed, particularly where the door includes several adjacent glazed sections. The replacement must also meet the appropriate safety requirements for glazing in a door, which will normally mean using toughened safety glass.
Why replace the glass rather than the whole door?
A complete new door should not be required to add a cat flap. If the frame, door leaf, hinges and locking system remain in good condition, changing the sealed unit provides a more direct solution.
Keeping the existing door means:
- No disturbance to the frame, threshold or surrounding finishes
- No need to match a new door to the property
- Less disruption during installation
- Continued insulation from a properly sealed unit
- Less waste from replacing serviceable components
The original glass remains in place until the replacement unit has been manufactured, so the door can continue to be used while the new glass is being prepared.
Cat flap in double glazing cost
The cost of installing a cat flap in double glazing depends on the size and specification of the replacement glass, the type of cat flap and the complexity of the fitting.
Larger units, patterned glass, specialist coatings and thicker glazing can affect the price. Microchip or electronic cat flaps may also require an adaptor or more detailed fitting than a basic manual model.
A quotation should cover measuring the existing unit, producing the replacement glass and fitting the cat flap securely. Providing the exact product details in advance allows the aperture and installation requirements to be confirmed accurately.
Dog flap in glass door installation
Crystal also provides dog flap in glass door installation for suitable double glazed doors, with patio door dog flaps the most common installation we carry out. The existing sealed unit is replaced with a new unit manufactured with an aperture for the chosen flap, allowing the door and frame to remain in place.
Dog door flaps for glass doors are available in various sizes, ranging from compact models to a large dog flap for a glass door. The aperture must be appropriate for both the pet and the dimensions of the glazed unit.
The dog flap in glass door price will depend on the replacement glass specification, flap size and any adaptor required.
Request a quote
If you would like to fit a cat flap on a glass door, contact Crystal for a no-obligation quotation.
We provide cat flap installation across Burnley, Pendle and Blackburn, replacing the existing sealed unit with glass prepared specifically for your chosen cat flap. We can assess the door, confirm what is required and provide a clear price before the new unit is ordered.