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Cat Flap Fitters FAQ

Below is a sample of our most frequent asked questions

The typical lead times for Cat Flaps and Pet Doors are 5 days from when we receive payment. see our payment policy

For an accurate estimate please send a photo using the contact form at the bottom of the page. 

Commonly we fit cat flaps into double glazed Bi Fold,  French doors and Patio doors, although as these are usually one of the largest pieces of glass in your home we try to advice customers to find a smaller alternative.

A question we are often asked by clients is why do we not fit cat flaps into composite doors.

We would not cut into them number of reasons, including that it could invalidate the warranty and that the cat flap opening in my experience is very difficult to seal to manufacturer standard.

The Conventional cat flap does not allow selective access. This leaves your home vulnerable to other creatures such as foxes using the door to invade your home and harass your Cat. Most common problem is other cats getting in and spraying your space!

Most Responsible cat lovers have their cats Microchip. The microchip cat flap has a scanner that reads your pet’s chip and gives access to Cats that have been programmed to that specific cat flap. This gives reassurances to owners that only their pet enters and exits the home.


As a cat flap fitter we are often asked about a draughts proof cat flap – the answer is that there is no such product on the market! You will get a draught from your cat flap whether it be in glass or brick installation.

The main reason being is that the moment the cat flap is opened,  it has created a draught, hence no cat flap manufacturer can claim that it is draught proof.  The only way you could avoid this would be like a hotel revolving door, that never actually opens as such –  you enter a compartment that then moves around to the opening so you can get out. This of course would not work for a cat flap. Neither could you have hot air blowing down like the supermarkets or high street shops do to keep the cold at bay.

The cat flap is a centuries old invention. Experienced cat owners know this pitfall of draught as a trade off for allowing their cat access to the outside world. The other option is to leave a window open which of course is worse in terms of draught. Alternatively, you could open the door or window on request of the cat but this is impractical if you are at work or it’s the middle of the night. The only option you are left with is to have a house cat and not allow it out.

With a cat flap, your cat has the freedom to go in and out without pestering you, and there is less foul odour of the litter tray.

Cat flap manufacturers do their best to try and minimise cold air coming through the flap when the cat flap is not in use through what they call draught excluders – essentially a brush like material around the flap that is meant to insulate it somewhat. However, you need to bear in mind that the actual flap must be light and easy to open for the cat to be able to push open themselves with ease. It cannot be sealed tight as it must swing both ways, or it would defeat the object.

You must also consider the current thickness of your wall or glass pane – insulated cavity wall depth of about 400mm or about 28mm for double glazing. When putting a hole in either of these for a cat flap, it is essentially replaced with a thin layer of plastic (the cat flap) that is obviously not as thick or insulated as the wall or double glazing that was there previously.

Predominantly, the question about draught is asked by new cat owners with their first kitten or rescue who are yet to experience the joys and pitfalls of owning a cat.  As a cat flap fitter, our role is to fit the cat flap you have chosen – we don’t manufacturer them  and I urge people who are thinking of owning a cat to do their homework on which cat flap best suits theirs and their cats needs. Check out the reviews too, there are many online.

Regretfully a new double glazed unit would be required rather than fitting to existing glass.

Double glazing cannot be modified as the glass is toughened and air tight and are made to measure.

We will always require the width height and cavity of the double glazed unit;

This unit is then made by a specialist double-glazed unit manufacturer. The glass must have the cut-out for the cat flap made in both pieces of glass before they go to be toughened. The double glazing manufacturers will handle all of this.

Building regulations require a 50 mm gap to the edge of the glass for your cat flap hole cut to maintain its integrity.

The new glass must be toughened, and the inner leaf should be Low E glass to comply with current regulations.

The most usual place for a flap to be fitted is in the back door, which will either be a full length or a half-length Glass or UPVC panel.

Please note that all glass for doors must be made from toughened safety glass, making the glass more expensive.

Fitting a Cat Flap into small windows is desirable as the cost of glass is charged per square meter – the smaller the glass, the cheaper the job, also glass that is not toughened safety glass is more cost effective to purchase.

We fit flaps into UPVC or aluminium framed doors that are double glazed.

Aluminium doors tend to be more expensive to install as it becomes a much more labour intensive task due to the nature of the door.

Commonly we fit cat flaps into double glazed French doors and Patio doors, although as these are usually one of the largest pieces of glass in your home we try to advise customers to find a smaller alternative.

For a double glazed glass panel, we will need to measure the glass width and height; we will also need its cavity.

A Vent Hole is cut in the glass and sealed so that the cat flap can be fitted; this cost is the same regardless of the height or width of the glass or panel.


Serious consideration needs to be given on where to fit a pet door as the security of your home could be compromised.

You will need to consider that a burglar may be able to reach through the cat flap after its fitted and access the door latch.

Never leave keys, wallets or any valuables where a burglar may be able to reach them through the cat flap hole.

A locking cat flap can, of course, lock to add extra security but this is a little counterproductive a microchip cat flap would provide additional security as it can only be opened from the outside by your cat’s microchip.

When considering large dog doors be aware that although unlikely burglars could climb through it, We would advise using security panel at night or when going out.

Pet-friendly movement detectors will be a good idea if you have a home alarm system fitte


To comply with building regulations toughened Safety glass must have a logo down in one of the bottom corners.

Clear Float Glass doesn’t have any writing on it.

The glass mounting adapter is compulsory for fitting a Sureflap to any glass surface -without the adapter the cat flap will simply not fit into glass

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