Fitting a Cat Flap in a UPVC Door

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

The ability of your cat to come and go out of the home at its own pace is a great idea to keep it physically and mentally active. A flap can aid in reducing accidents due to toilets by making it easier for your cat to exit the house whenever it wants to.

Measure the Door

A cat flap allows your pet to move around as they'd like without needing to open the door. This makes it ideal for keeping them in the home when you're away, and helps keep unwanted pests out of your home too!

It is essential to measure the door before you purchase a cat flap as there are various sizes available. This ensures you get the correct size to fit inside your door made of upvc, otherwise, it could be too small or too large, and your cat may have trouble using it.

Get a ruler and determine the width at several locations along the edge of the door. Also, take measurements of the door's height in a few spots. A door that is too high will make your cat do an acrobatics routine each time it is tempted to use the flap.

Get help from a glazier if you aren't sure what to measure for the door. They'll be able help you determine whether or your door is suitable for a cat flap and help you decide on the best size of flap to purchase.

Draw the outline of the hole on your door after you have taken your measurements. This will assist you when you cut the hole and save you money!

You must also ensure that the hole you're creating is in the right place. For example, if you're installing the cat flap inside the patio door, you must ensure that the hole is not too close to hinges, as this can cause leakage and problems with the seal.

It is best to delegate the installation of a cat flap on a glass door to an experienced glazier. It can be very tricky to insert a cat flap into an existing pane of glass, and you may be surprised to find that the process causes it to crack and lose its weatherproof seal.

Measure the Cat

A cat flap allows your pet to move around whenever they like without having to leave them alone. It also stops draughts from entering your home, which isn't good for you or your cat.

If you own a uPVC door or composite door, it could be difficult to install the cat flap. These doors are constructed of different materials and the installation is different. Before you decide to install the cat flap on your uPVC or composite door, ensure that it is compatible and that you've checked with the manufacturer as any modifications could invalidate any warranties.

These doors are generally designed to be tough and durable and have insulation. This makes them more resistant to elements of the weather than other types of doors, but they can be difficult to install the cat flap. Get advice from a professional before installing a cat flap onto a uPVC door or composite.

To ensure that your cat can get through the door, you'll need measure their height. It's easier to measure their height when they're at peace or asleep, which means they aren't moving around. Once you know their height you can measure the distance between their stomachs and the floor in order to determine the position of the bottom of the flap. This position is marked on the door.

If your composite or uPVC door is made from metal (either aluminium or steel), you'll need to be very careful when cutting it using power tools. The drilling process can make cracks, especially if the area is made of toughened glass. This is why it's recommended to employ an expert glazier to install your cat flap inside the glass pane. This will prevent the glass from breaking and becoming brittle. A glazier will also be able to provide you with a circular cat flap hole that is less likely to break and is safer for your cat to use.

Cut the Hole

If it doesn't however, you can make one yourself using a sheet of thin paper (tracing paper is ideal). If it doesn't, you can make your own with a thin piece of paper (tracing papers are ideal). After the shape is drawn on the door you can then use a spirit level to make sure that the shape is completely horizontal. This will ensure that your cat flap is positioned correctly in the opening and will not slide open or close.

Then, make use of a jigsaw to cut out the pattern that is marked on the door. Use a blade designed specifically for uPVC doors. It is usually marked with this information. If not you can ask the staff at the DIY store for assistance. Once the hole is cut then place the flap against it and open it, making sure that the flap moves smoothly. If it binds on any points then you can use a file or a sandpaper to fix this.

Verify that there aren't gas or electric pipes inside the door you plan to cut through. The jigsaw may damage them. Also, be aware of any handles, or other fittings on the door that have to be removed to fit the cat flap. Be careful not to scratch these objects during the process.

The majority of people who install a cat flap on their own have the standard solid uPVC front door, meaning they won't be faced with these issues. If your door is constructed of timber or has a decorative panel that cannot be removed, it will increase the difficulty of the job.

For these kinds of jobs, it is worth getting expert advice from a cat flap fitter. It is important to complete the job correctly to avoid any future issues. Getting it wrong can result in the door becoming damaged, which could invalidate the warranty.

Place the Flap

Once you've got your hole cut, put the flap on to see if it fits and can be opened easily. If you spot any areas that stick or catch to the door, smooth them out using an sandpaper or hand file until it fits correctly and opens without issue. Be sure that the flap is aligned with the door.

If  cat flap installers repairmywindowsanddoors  doesn't have an example, you could make use of thin paper such as tracing or acetate. Place the paper on the door and mark the area where you'll will need to place the flap (this will serve as your cutting guide). Then, using the pencil lines you've made on the door, mark four screw holes in each corner of the flap. These will be the screws you'll use to put the flap into place.

Most uPVC door are solid and easy to cut. If the door is made of composite or GRP however, it could be more difficult. If you're unfamiliar in this area, it might be advisable to hire a professional to handle the job for you. They will also be able to advise you on whether or not your particular door is suitable for cat flap installation.

You can install the cat flap onto composite doors, but it is important to check with the manufacturers or a professional joiner prior to making any changes because any changes to these doors could invalidate the warranty. If you choose to carry out the work yourself, remember that this could be messy and dangerous task.


You'll require a saw or grinder to cut through composite doors more than just the GRP. Be aware that this can be a very hazardous job and you'll have to take extreme care not to harm the door or yourself as it is very fragile. It's important to remember that cutting a hole in any type of door glass is a lot more difficult than making the same modification in the case of a uPVC or solid wood door.