Cat Flap in a Bi-Fold Door: Yes — Here's How (UK Installer's Guide)

Can you fit a cat flap in a bi-fold door? Yes. We do it by ordering a brand-new toughened glass unit with the cat flap aperture pre-cut at the factory, then fitting it into one of the bi-fold panels — usually in the corner of the door where it's most discreet.

The cat flap we recommend for bi-fold doors is the Pet-Tek (formerly Dogwalk). It's a manual (non-microchip) flap with a slim profile, ideal for this application because the door still slides, opens fully and closes fully with no issues.

If you prefer microchip security, we can also fit a SureFlap or PetSafe microchip cat flap into the same new glass unit — the microchip reader protrudes only slightly beyond the glass and doesn't interfere with operation.

If a fixed side panel or nearby window is available, that's sometimes an alternative — but fitting directly into the bi-fold panel itself is absolutely possible and works brilliantly.

The process is straightforward, but it must be done correctly:

• We never cut existing glass. Bi-fold panels are toughened (and usually double or triple-glazed). Toughened glass cannot be cut after manufacture — any attempt will shatter the entire pane. Instead, we measure your existing panel and order a brand-new toughened glass unit from our supplier with the cat flap aperture pre-cut before the glass is toughened.
• Corner placement for discretion. We advise fitting the hole into the corner of the door rather than the centre. It's far more discreet — less visible from inside and out — and your cat uses it just as easily.
• The bi-fold still works perfectly. The new glass unit is the exact same size and weight as the original. The door continues to slide, fold, open fully and close fully exactly as it did before. We've fitted dozens this way and the operation is unaffected.
• Weathertight seal maintained. Because we're replacing a full glass unit within its existing frame — not cutting the frame itself — the weather seal and structural integrity of the door system remain intact.

For bi-fold installations, we recommend the Pet-Tek cat flap (formerly branded as Dogwalk). Here's why it works so well in this specific application:

• Slim profile: The Pet-Tek is designed with a low-profile frame that sits neatly within the glass aperture without protruding excessively into the folding mechanism.
• No interference with operation: The door still slides smoothly on its tracks, opens fully and stacks correctly, and closes fully without the cat flap catching or obstructing anything.
• Robust build: Pet-Tek flaps are built to withstand daily use and the slight vibration that bi-fold panels can experience when being opened and closed.

Pet-Tek is a manual cat flap — no batteries, no microchip reader, just a simple, reliable flap. If you prefer microchip security, we can fit a SureFlap or PetSafe microchip cat flap into the same new glass unit. Both brands' microchip readers protrude only slightly beyond the glass and don't cause operational issues with the folding action.

If you'd rather not modify the bi-fold panel itself, or if one of your bi-fold panels is a fixed (non-opening) side panel, that can also work well.

Why it works:
• The panel doesn't move, so there's zero question about folding interference
• We order a new toughened glass panel the exact same size as the existing one, with the cat flap aperture pre-cut
• The original panel is removed and the new one slots straight into the existing frame
• Weather seal stays intact because the frame isn't touched

Lead time: Typically 7–10 working days for the bespoke glass to arrive, then fitted in a single visit.

From cost: £280 (covers a new toughened glass panel and full installation).

If your bi-fold configuration doesn't suit either of the above, we can look at a nearby window or a separate door within a few metres:

• Adjacent window: Kitchen, utility, dining room or a low-level window in the same wall. We fit cat flaps into double-glazed units, single-glazed windows, UPvc, aluminium and timber frames regularly.
• Separate door: A back door, utility door or side door is often the cheapest route — UPvc doors from £60, composite doors from £80.

The cat doesn't care which door or window they use — as long as the route is clear and accessible from where they naturally come and go.

To be straight with you, here's what we won't quote for on a bi-fold:

• Cutting an existing bi-fold panel — the glass will shatter. We only fit new, factory-prepared glass units.
• Cutting the aluminium frame — bi-fold frames are structural; cutting them weakens the whole system.
• "Pet door inserts" advertised online — these are designed for sliding patio doors and don't work with the way bi-folds stack.

If another installer has offered to cut your existing glass or frame, please ask them in writing how they're handling the weather seal and the glass manufacturer's warranty position. The answer matters.

For bi-fold door installations, our first recommendation is the Pet-Tek cat flap. It's a manual (non-microchip) flap specifically well-suited to glass-panel bi-folds because of its slim profile and the fact it doesn't interfere with the door's folding action. The door slides, opens fully and closes fully without issue.

If you prefer microchip security, we can fit a SureFlap Microchip Cat Flap or a PetSafe Microchip Cat Flap into a bi-fold glass unit too. The microchip reader protrudes slightly beyond the glass, but in our experience this does not cause any operational issues — the door still folds and seals correctly.

For larger cats or small dogs, the SureFlap Microchip Pet Door has a bigger opening and a built-in curfew timer.

You can buy the cat flap yourself from Amazon and we'll fit it, or we can supply and fit in a single visit.

Every bi-fold setup is different. The best thing you can do is send us:

• A photo of the bi-fold from inside, showing the full run of panels
• A photo from outside showing which panel you'd prefer the flap in
• A photo of any fixed side panel or nearby window that could be an alternative
• Your postcode

We'll come back with a clear recommendation — whether that's a new glass unit in the bi-fold panel itself (corner placement for discretion), a side panel, or an alternative route. Lead time, price and no pressure. We cover Manchester, Cheshire, Liverpool, Wirral, Warrington, Stockport, North Wales and Staffordshire.