Frequent Asked Questions.

Lead times are ten to fifteen working days once we have the right measurements and have received payment from you. see our payment policy

This is the length of time it takes the glass manufacturer to produce the new sealed unit.

You don’t necessarily need to be home when we come to measure, we can measure from the outside if access is easy? 

By providing a photo of the glass we can give you the exact price. If you are unable to provide a photo of the glass, then kindly provide some rough dimensions. Without a photo or dimensions, unfortunately we cannot accurately quote. 

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.

One advantage of fitting a cat flap through brick is that it’s possible it can be done DIY with the correct power tools and skill set, whereas installing a cat flap through a double glazed window cannot. I have previously written a blog on why you can’t cut through existing double glazed units to fit a cat flap and why a new pane of glass/double glazing has to be manufactured. Click here to read

A DIY cat flap install through your cavity wall may seem at first an obvious solution to the problem of allowing the cat access via a cat flap, but be warned that it is messy, time consuming and can be very stressful. Also, it is vital that for health and safety reasons, you are certain that no services/wiring are present in the wall before you attempt to bore out the brickwork.

If are not confident in your DIY skills to fit a cat flap through a wall yourself, then I`m in no doubt you will need to consult with a qualified builder to do it for you, which again will still be messy, time consuming and can be more expensive than installing a cat flap in glass.

With a cat flap in glass installation, the fitting can be fast and is much cleaner, with little to no dust or debris to clear away.  Glass installations are usually more cost effective than going through brickwork and the cat will benefit from being able to view through the glass to spot any potential dangers/bullies before it exits.

Another advantage of installing the cat flap through glass is that should you choose to move home in the future, then the original pane of glass can be put back into the frame quickly and cleanly for the new owners/tenants. Rebuilding the cavity wall is a lot more difficult, stressful and expensive.

If you are a tenant, then a landlord will never allow you to fit a cat flap through a cavity wall for fear of dilapidating the building. This is not a problem with fitting a cat flap in glass as by the nature of glass installs, the frame is designed to be opened so that glass can be changed and can easily be rectified (original glass put back in again) before you move out.

Furthermore, some potential house buyers will be averse to purchasing a home with a hole in the cavity wall. Another advantage of putting the original pane of glass back in is that you can take your cat flap with you to your new home saving you money on purchasing a new cat flap. Also you never know, you may get lucky, and the pane of glass with a hole in it may fit into a frame in your new property.

In terms of heat loss there is no difference in either, both cat flap installation options will be draughty as cat flaps are by nature and sadly are not very energy efficant– I have previously written an in depth blog on this subject please read more on this by clicking here.

A lot of modern houses are now made with about 25% more glass, so often, installing into a glass window or door is an easy option. Some homes have floor to ceiling glass but you may be lucky and find a small side panel which would be perfect for a cat flap fitting.

If going through a wall is your preferred route or only option you have for your home, I strongly advise you to consult with a qualified builder first, and always ensure they have relevant building experience, qualifications, insurance and that they can comply with all building regulation

We do not install through cavity walls; we recommend that you hire a professional builder for this type of installation.

Cat flap installation in a brick wall has many pitfalls; it is messy, expensive and time-consuming.

If this is your preferred route or only option you have for your home, we strongly advise you to consult with a qualified builder before considering installing a pet door through a wall, always ensure they have relevant building experience, qualifications, insurance and that they can comply with all building regulations.

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 our 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 Microchipped. 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.

Please be aware cat flap hole sizes are not interchangeable should you decide that you need a microchip product or a larger pet door at a later date. You get one opportunity to get the hole size right and we urge you to take this into consideration when making you pet door choice.  

Over the years we have dealt with every type of cat flap and the ones on our website Advice page are genuinely the ones that in our experience we believe to be the best in terms of robustness, durability, length of warranty, and value for money. We are cat flap fitters and not the cat flap manufacturer. Therefore we have included a link to the official website on each cat flap we supply so that you can gain further knowledge on each product on our advice page.

We don’t know your cat, so please be sure to select the most appropriate cat flap for your cat’s size, weight and needs –  We also recommend that customers use the flap sizes to cut a hole in a cardboard box to see if the cat/dog will fit through it ok.


Sureflap Cat Flap works on 4 x AA batteries. The Pet Door works 4 x C Batteries. 

Batteries are not included with any Sureflap products they must be purchased separately. 

Often we are asked how long will they last before they need changing? It’s almost impossible to know it could be weeks or month much depends on the number of cats using the device the frequency of usage and any intruders trying to enter your home.

We urge you to have a spare set in the event of them running low. Sureflap recommends you to use high-quality batteries that will give a more consistent source of power. This rules out the use of  rechargeable batteries or zinc batteries. It is always best to buy alkaline batteries.

Your device will give you hints that it is running low, the red light will flash if running low. Or the mechanism will flick up and down slowly without any cats being nearby. Please refer to your manual for further information.

Changing batteries resolve most issues of the cat flap not working. Don’t fear unless you reset the cat flap to factory settings the cat flap memory will always remember your cats’ chip number after replacing batteries.

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 fitted


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.

Using a Cordless Jigsaw the install should take about forty minutes, once we have cut the hole we install your chosen Cat Flap.
No need to measure beforehand we just need to book an appointment.

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

All our double glazed sealed units come with a 5 year guarantee. 

The warranty lies with the manufacturer of the cat flap.

All new Cat flaps/ Pet doors  products, carry a 3-year warranty.

After Install we will always follow up to remind you to activate your cat flap / pet door warranty.

Unfortunately, we have to charge more for a wood frame as it is a much more labour-intensive task than a uPVC Frame Installation. Fitting should take about one hour sometimes two.

At survey stage, may have to decline the project depending on the condition of the frame and how the glass is currently glued/pinned in.

Please note that if proceeding with the install, this will be a glazing `hack out`, It will be your responsibility to redecorate afterwards, we strongly advise clients to wait a period of a week before you can touch up with paint so that the silicone or putty can dry properly. A gazing `hack out` is not as brutal as it sounds. As qualified and experienced Glazers, we will always endeavour to be as delicate as possible. However, there is an increased probability that the original glass may break on removal, dependent on how tight the wood fits around the glass.

In rare cases, the original glass is not pinned into the timber but glued at manufacturing level during production at the factory. If this is the case, we are left with no option but to break the glass to enable us to remove it.  Also, a side effect of removing the original glass from timber is that the wood bead may splinter.

We have no alternative but to cut away at the original paintwork ( often some older frames will have layers of paint jobs );