Fitting a Cat Flap in a UPVC Door

· 6 min read
Fitting a Cat Flap in a UPVC Door

The freedom to let your cat move around the house as it pleases is an excellent way to keep your pet active and mentally stimulated. A flap can aid in reducing accidents due to toilets by making it easier for your cat to exit the house when it needs to.

Measure the Door

A cat flap lets your pet come and go whenever they'd like without needing to open the door. This makes it perfect to keep them in the house the home when you're away, and helps keep unwanted pests out of the home too!

It's important to measure the door before you purchase the cat flap, as there are a variety of sizes available. This ensures you get the right size to fit into your upvc door, otherwise, it could be too small or large and your cat will be unable to use it.

Before doing anything but use a ruler to take measurements of the length of the door in a variety of locations along its edge. You should also take measurements of the door's height in a few places. This is because a door that is too high will cause your cat to do an exercise routine like a gymnast every time they use the flap!

Ask a glazier for help when you're unsure of what to measure for the door. They should be able to assist you in determining whether or the door you have is suitable for a cat flap and help you decide on the best size of flap to buy.

Once you've got your measurements, the next thing to do is to mark out the shape of the hole in the door. This will aid you when you cut the hole and save you money!

Make sure that you put holes in the right location. For instance, if you're installing the cat flap on a patio door, you must ensure that the hole is not too close to any hinges, as this can cause leakage and damage to the seal.

It is recommended to leave the task of installing the cat flap on a glass door to an experienced glazier. It may be difficult to install a cat-flap within an existing pane. It is also possible that it cracks and loses its weatherproof seal.

Measure the Cat

A cat flap allows your pet to come and go whenever they like without needing to leave them alone. It can also help to stop draughts from entering your house, which aren't good for either you or your cat!

If you have a uPVC door or composite door, it could be difficult to install the cat flap. These types of doors are often made of different materials than standard wooden or uPVC doors, and the installation process is quite different too. Be sure to check with the manufacturer if it is compatible before you install the cat flap on your uPVC composite or uPVC door.  cat flap installer near me repairmywindowsanddoors.co.uk  may cause warranty issues.

They are designed to last and are tough, with insulation. This makes them more resistant to elements of the weather than other types of doors, but they may be difficult to fit the cat flap. If you're uncertain about whether your uPVC or composite door is able to accommodate a cat flap, check with a professional joiner prior to starting.

To ensure that your cat is able to access the door, you'll need take a measurement of their height. It's easier to measure their height when they're calm or asleep, so they don't sway around. Once you have their height, you can measure the distance from their stomach to the floor in order to determine the position of the bottom of the flap. Then, you can mark this position on the door.

If your composite or uPVC door is made from metal (either aluminium or steel) you'll need be extra cautious when cutting it using power tools. Cutting into metal can cause it crack, especially when the area is composed of toughened glass. This is the reason it's recommended to employ an expert glazier to install your cat flap in glass. This will prevent the glass from becoming brittle or shattering. A Glazier is also capable of providing you with a cat flap that is less likely to break and safer for your cat to use.

Cut the Hole

A good cat flap will come with a drawing template that can be used to mark the location on your door where the hole needs to go. If it doesn't, you could create your own by using a thin piece of paper (tracing papers are great). After the shape has already been penciled on the door, use your spirit level and make sure it's horizontal. This will allow your cat's flap to be properly seated in the door and prevent it from being able to slide open or closed.

Next, take your jigsaw, and cut the shape marked on the door. Use a blade that is specifically designed for uPVC door use. It will usually be marked with this information. If not then ask the staff at your DIY store for assistance. Once you have the hole drilled then place the flap against it and then push it out to ensure that the flap's action is smooth. If it is bound at any point, use a filer or rasp to fix this.

Check that there aren't any electric or gas pipes in the door you're planning to cut through. Your jigsaw could damage them. Similarly you should be aware of any handles or other fixtures on the door which will need to be removed to make room for the cat flap. Be careful not to harm them in the process.

Most people who install a cat flap on their own have a standard solid uPVC front door, so they won't have to deal with these problems. But, if your door is made of timber or has decorative panels that cannot be removed, this could increase the difficulty of the task.


For these types of jobs, it's worth getting expert advice from a cat flap fitter. It is crucial to do them correctly to avoid any future issues. Making the wrong choice could cause the door to be damaged, which could make it impossible to honor the warranty.

Place the Flap

Once you've got the hole drilled, place the flap in place to test whether it is able to open easily. If you find any points which catch or stick, use a hand file or sandpaper to file them down until they fit properly and open without any problems. Make sure the flap is aligned with the door.

If your tool doesn't have an example, you could use tracing paper that is thin, such as a piece of paper or acetate. Lay the paper against the door and draw an area on which you'll need to position the flap (this will be your cutting guide). Then, using the pencil lines you've drawn on the door, mark four screw holes in each corner of the flap. These will be the screws you'll use to fit it in place.

Most uPVC doors are solid and therefore simple to cut into. However, if your door is made from GRP or a composite then it can be more challenging. If you're not familiar in this area, it might be advisable to hire a professional to handle the work for you. They can also inform you if the door is suitable for the installation of an animal flap.

You can fit the cat flap onto composite doors but it's important to check with the manufacturers or a professional joiner before you do so since any modifications to these doors may invalidate the warranty. If you do decide to complete the task yourself, remember that this could be messy and possibly hazardous task.

You'll require a grinder or saw to cut through composite doors rather than only the GRP. Be aware that this could be a very hazardous job and you'll need to take extreme care not to harm the door or yourself since it is extremely fragile. It's worth noting that it is much more difficult to create the door glass than in a uPVC door or a solid wood doors.