Pet Doors for French & Bifold Doors
French doors and bifolds are lovely to live with, but they leave a lot of homeowners stuck when it comes to giving a pet its own way in and out — the panels are glass, and you can't just cut a hole in a finished pane. The good news is you can absolutely fit a cat or dog door into French, bifold or patio glass. The trick is the round cut-out that every Catwalk® and Dogwalk® glass door is built around. Here's how it works, how to tell if your panels are wide enough, and what to expect from the install.
- Pet doors fit French and bifold doors through a single round hole cut into one glass panel — installed by a glazier, not glued on.
- Your panel needs to be wide enough for the round cut-out (245mm for a cat, up to 385mm for a large dog) with glass to spare around it.
- If the door is double glazed, the hole has to be cut before the unit is toughened and sealed, so you order a new pre-cut panel rather than drilling the one you have.
Why the round cut-out suits French & bifold doors
French and bifold doors tend to have tall, fairly narrow glass panels, and that's exactly where a round hole works better than a square one. A circle has no corners, so stress spreads evenly around its edge and the glass is far less likely to crack — during the cut or years later. It's also a single, clean core-drill rather than four cuts and four weak corners. That's why glaziers prefer it, and it's what makes a neat pet door in a slim French-door pane realistic in the first place. There's more on the engineering in why glaziers prefer the round cut-out.
Will it fit your glass panel?
This is the first thing to check. The door sits over a round hole, so your panel has to be wide enough for that hole plus a margin of glass all the way around it — a glazier will confirm the minimum glass they need to leave for a safe install. As a starting point, measure the visible width of a single glass pane in your French or bifold door and compare it to the cut-out size for the pet you have:
- Cat — 245mm round cut-out
- Large cat or toy dog — 267mm
- Medium dog — 320mm
- Large dog — 385mm
If a single pane is too narrow for the size you need, a glazier can often advise on the best panel to use, or whether a smaller door suits. When in doubt, the quickest answer is to run your measurements through the door finder and then have a glazier check the panel.
Single glazing vs double glazing
If your French or bifold door is single glazed, a glazier can core-drill the round hole into the existing pane. If it's double glazed — which most modern doors are — it's different: you can't drill a finished, sealed double-glazed unit. Instead, a new sealed unit is made for that panel with the hole already cut into the glass before it's toughened, then delivered ready for the door to fit.
Which door for your pet
Match the door to your pet and the pane, then let your glazier confirm the fit:
| Your pet | Model | Round cut-out | Glass |
|---|---|---|---|
| Cat | Original glass cat door | 245mm | 3–10mm |
| Large cat / toy dog | Maxi Pet Door | 267mm | up to 28mm (double glazing) |
| Medium dog | Intermediate dog door | 320mm | up to 32mm (double glazing) |
| Large dog | Standard dog door | 385mm | up to 32mm (double glazing) |
How it's installed
Fitting into glass is a glazier's job, not a DIY one. For single glazing, they core-drill the round hole and clamp the door over it, with the flap's brush seals keeping weather out and the 4-way locking letting you set it open, in-only, out-only or locked. For double glazing, they swap in the pre-cut sealed unit and fit the door to that. Either way the finished result is a proper, sealed pet door in your French or bifold door — not something glued on that leaks or looks like an afterthought.
Frequently Asked Questions
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