Cat flaps and dog flaps are a fantastic way to give your pets the freedom to come and go while keeping your home secure and comfortable. One of the most common questions homeowners ask is:
“Can cat flaps and dog flaps be installed into double glazed glass?”The short answer is
yes — but there are a few important things you need to know before installation.
Can You Cut a Hole in Existing Double Glazed Glass?
Double glazed glass cannot usually be cut after it has been manufactured. This is because double glazing consists of two panes of glass sealed together as one insulated unit. Attempting to cut into existing toughened or insulated glass will cause the glass panel to shatter. Instead, a new double glazed panel must be ordered with the hole pre-cut during manufacturing.
The same applies to:
- Toughened safety glass
- Insulated glass units (IGUs)
- Low-E glass panels
- Most modern sliding door glass panels
This ensures the glass remains structurally sound, safe, and energy efficient.
How Does Installation Work?
Installing cat flaps or dog flaps into double glazed glass is a straightforward process when completed correctly.
The typical process includes:
- Measuring the existing glass panel
- Checking the required hole size for the flap model
- Ordering a new glass unit with the hole pre-cut
- Removing the old glass panel
- Installing the new glass panel
- Fitting the cat flap or dog flap into the prepared opening
For the correct hole dimensions, always check the technical details for your chosen model before ordering glass.
Are Cat Flaps & Dog Flaps Suitable for Sliding Glass Doors?
Yes — many modern cat flaps and dog flaps are designed specifically for glass and sliding door installations. Most Pet-Tek glass fitting models are compatible with:
- Sliding glass doors
- Hinged glass doors
- Fixed glass panels
- Double glazed windows
- Toughened glass installations
- Laminated glass installations
This makes them a popular option for apartments, modern homes, and properties with large glass areas.
Recommended Pet-Tek Glass Fitting Models
we recommend the following Pet-Tek models for double glazed glass installations:
Small to Medium Pet Options
Medium Pet Options
Medium to Large Pet Options
These models are specifically designed for glass installations and are ideal for both cat flaps and dog flaps in modern homes.
Benefits of Installing Cat Flaps & Dog Flaps in Glass
Installing a flap into glass offers several advantages:
Cleaner Appearance – Glass-mounted flaps often look more modern and discreet compared to wall installations.
Better Natural Light – Your door or window retains its open feel without bulky panels.
Convenient Pet Access – Pets can access outdoor areas independently throughout the day.
Reduced Scratching & Barking – Many owners notice less scratching at doors and fewer requests to be let outside.
Great for Apartments & Sliding Doors – Glass fitting options work particularly well in homes with limited wall space.
Things to Consider Before Installation
Before installing a cat flap or dog flap into double glazed glass, keep the following in mind:
- The glass must be replaced with a new pre-cut panel
- Accurate measurements are essential
- Hole sizes vary between models
- Professional glass installation is highly recommended
Taking the correct measurements the first time helps avoid delays and unnecessary replacement costs.
FAQ
Can existing double glazed glass be cut for a cat flap or dog flap?
No. Existing double glazed glass cannot usually be cut once manufactured. A new double glazed glass panel with a pre-cut hole is normally required.
Do I need toughened glass?
Yes. Toughened safety glass is recommended and commonly required for pet flap installations in single pane doors and windows.
Can cat flaps and dog flaps be installed into sliding doors?
Yes. Many Pet-Tek glass fitting models are compatible with most sliding glass doors.
Will installing a flap affect insulation?
When installed correctly into a properly manufactured double glazed unit, insulation performance remains very good.
How do I know what hole size I need?
Each flap model has a specific cut-out size. Always check the technical specifications for your chosen model before ordering glass.
Can I install the flap myself?
The flap itself may be DIY friendly, but replacing double glazed glass panels should usually be completed by a professional glazier.
Which models are best for double glazed glass?
Popular Pet-Tek models for double glazed installations include:
Final Thoughts
Cat flaps and dog flaps can absolutely be installed into double glazed glass when planned correctly. The key is ensuring the replacement glass panel is manufactured with the correct pre-cut hole size from the beginning. With the right model and professional installation, glass-mounted pet flaps provide a clean, modern, and practical solution for giving your pets more independence while maintaining the look and performance of your home.
