Technical Advice | Glazing Applications

Cat Flaps in Glass Doors

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Rebecca Clayton

Written by Rebecca Clayton

Edited by Dan Finnegan

Fact-checked by Michal Piekarewicz

Aug 19, 2026

Last verified: Aug 19, 2026

Next review: Aug 19, 2026

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Integrating Cat Flaps Into Bespoke Glazing Systems.

Having bespoke glazing systems designed for your project allows for a huge number of possibilities and options to suit your specific needs. At IQ, we occasionally get asked if it is possible to install cat flaps in glass doors and how that process would work. Over the years we have worked on a handful of projects in which we have installed cat flaps that sit within our glazing, offering easy indoor to outdoor access for a pet.

 catflaps in glass doors

Frequently asked questions regarding cat flaps in glass doors:

Do Cat flaps in Glass Doors Increase Costs?

Installing cat flaps into a bespoke glazing system will increase the cost of the system overall. This is because it is a highly specialized job with highly accurate glass cutting required. The process also increases the risk of glass breakage until the system has been installed.

What Types of Doors Can Have Cat flaps?

Due to all of our systems being fully bespoke, we can integrate a cat flap into any glass door as long as it is wide enough. This provides the freedom to be creative with the cat flap and fully customize the opening size.

Do Cat flaps in Glass Doors Effect Thermal Performance?

With a cat flap installed in a glass door, you are unfortunately sacrificing the thermal performance of the system. You would essentially be cutting out a portion of a thermally efficient material and replacing it with plastic that then opens and closes throughout the day.

Cat flaps in Glass Doors – Project Examples

Quarrendon Street

This home in Fulham, London has all black bi-folding doors installed for garden access from the kitchen area. Within the bi-folds is a white upvc cat flap which allows the family cat to come and go as they please. In this case, the owners opted not to colour-match the cat flap to the frames of the glass doors.

Chandos Road

When the owners of this London home wanted to increase the amount of usable space, they decided to build a side infill or side return extension. For the new extension, structural glazing and a glass door were requested in order to create the most minimalist design possible and to maximise natural light throughout the interior.

For Chandos Road, the small glazing feature next to the exit door is where the cat flap is installed. This was done as it was more cost effective to install the cat flap here instead of enlarging the door and installing it within such a large pane of glazing.