how does the Petflap work

How does the Petflap work?


How does the Petflap work? By using any air flow to shut more tightly.

The Petflap is pressed more firmly shut with any change in air pressure, whichever side it comes from. High winds outside push the door more shut; a breeze in the house through open windows, and doors opening or closing inside the house, also push the Petflap more shut.

This is because the Petflap has an assymetric cut: the frame extends slightly further inwards on one side than the other, on opposite sides front and back, giving the door a lip to press against no matter which direction the airflow is coming from.  This gives the Petflap an ‘in’ and an ‘out’ side, which cats quickly get the hang of. It’s why the pet access door has its characteristic offset shape.

It’s easy for a pet to open the Petflap as there is no force for them to overcome. Airflow or a breeze presents a broad force that pushed the door shut against the frame. A nose or paw (or hand, if you’re testing it before fitting) provides focussed pressure that allows the door to open easily. Our draughtproof Letterplate Eco works on the same principle.

How is this better than standard catflaps?

how does the petflap workMost catflaps use magnets to keep the flap shut. Once enough force is applied to either side of the door it will open. This will happen with wind outside blowing against it or even doors opening and closing inside the house that act like a piston of air pressure and pop it open.

Once the magnetic force is overcome a gentle breeze can keep the traditional cat flap or dog flap open allowing cold air in and your warm air out. Even in hotter climates the expensive air-conditioned cool air flies out at the bottom of the door and the warm air pours in.

Some more modern chip access pet doors lock shut so they can’t blow open. These are a bit better but as they depend on opening quickly when the cat approaches, they have gaps all around the thin usually transparent door plate so they open easily, which means the air can gust round all the time.


how does the petflap workNo magnets, harsh springs or motors are needed. There is no need for your pet to push against them or have its tail trapped as the door slams shut.

As your pet doesn’t need to push hard to enter, this is no matching force pushing the door shut behind it. The Petflap’s gently tensioned pivot will close at your pet’s pace.

No matter how harsh the weather and wind, the door stays draughtproof but opens with a tiny amount of directed force.



The Petflap is made of several layers of insulating materials. The pet access flap is 14mm thick. It’s made up of 6mm of tough coated ABS plastic, 6mm of sustainable tricoya wood and 6mm thick acrylic windows. Two 1mm EPDM sponge layers help to seal air-flow and quieten the close noise – so no swinging, flapping doors.

The Petflap is currently undergoing thermal value analysis and air leakage testing for the passivhaus market. Generic materials values were used, which give a conservative working U-value of 3.521 W/(m²K). We’ll publish the air leakage results when we have them.

Extended trunking and bespoke

how does the Petflap workFor thick walls up to 60cm thick we can provide extended trunking to protect your wall and insulation materials from water ingress. For trunking over about 240mm we inset a second petflap to further insulate the trunking both thermally and acoustically.

Petflaps with extended trunking can be made in black, white or silver or a mixture of all three, but please note we can’t make silver trunking.

We can work with you to create a solution to awkward spaces, existing holes, existing pet doors and pets with special requirements. The Petflap will soon be available with a square front frame as standard. This is usually used to cover an existing enlarged square hole. We willingly turn our hand to all sorts of situations.


Our Petflap can be installed in walls, doors and glazing without special adapters, kits or models. Our round hole can easily be cut in any normal building or structural material.

Although our door fits into glass well, as with any kind of pet door fitting into modern glass the glazing panel needs to be a replacement panel precut by a fitting company that fits accurately into the the window frame. This can be more affordable in smaller glass sections and the original panel can be refitted in minutes if you are in rented accommodation. In most situations we can advise you of a fitter that can help.

We can supply the exterior grade silicone sealant recommended as our products need no screws or bolts to fit. This method of fixing creates a great seal between the outside and inside and few things will do that better than a hidden coating of silicone sealant/adhesive.


We are keeping plastic in the product only where we have no other sustainable solution at present. We have replaced a large section of acrylic with tricoya, a form of sustainable wood that will not require chemical sealants, fungicides, insecticides or stabilizers. Essentially it is a wood pickled using a vinegar and it will last for at least 50 years, even 25 years under ground or water (not salt water).

Points to consider

Because we use an ‘in’ and an ‘out’ side, the door hole you need to cut is wider than for most pet doors. Mostly this is not a problem but some expensive composite doors have structural needs and allow only specific areas that can be cut out.

Whether fitting our Petflap or any other form of pet door in walls, glass or doors, we recommend you check with the manufacturer or your builder or fitter for limitations if you have any concerns.

Our standard door is fine even for larger cats but some owners feel their cat needs more room. We do now offer the Maxflap, a larger square shaped option as a door and wall installation. It is entirely made of sustainable tricoya to a total of 20mm thick, and is suitable for small to medium sized dogs too. It is too large to safely fit into glazing

Chip access control is not yet available but we have plans for a revolutionary use of chip access control. This is in development and we hope to release it during 2021.