Fitting a Cat Flap in a UPVC Door

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

Allowing your cat to enter and go out of the home at its own pace is a great idea to keep it mentally and physically stimulated. A flap can aid in reducing toileting incidents by making it easier for your cat to leave the house when needed.

Take a measurement of the door

A cat flap allows your pet to come and go whenever they want without you having to open the door. This makes it ideal to keep them in the house when you're at home or away, and helps keep unwanted pests out of the home too!

It is important to measure the door to ensure you get the correct size cat flap. There are many sizes available. This ensures you get the correct size that fits into your upvc door, otherwise, it could be too small or large and your cat will be unable to use it.

Take a ruler, and determine the width at several places along the edges of the door. You should also measure the height of the door in a few places. This is because the door that is too high could cause your cat to perform the gymnast's routine each time they need to use the flap!

Get help from a glazier when you're unsure of how to measure the door. They'll be able to determine if your door is suitable for cat flaps and can advise you on what size flap you should purchase.

Mark out the shape of the hole on the door once you have the measurements. This will assist you when you cut the hole and will save you money!

You should also make sure that the hole you're creating is in the right place. If you're fitting an apex flap to a patio door it is vital that the hole doesn't get too close to the hinges. This could result in leakage or issues with the seal.

If you have glass doors it is best to leave this task to a glazier. It can be difficult to install a cat-flap in an existing pane. It is also possible that it breaks and loses its weatherproof seal.

Measure the Cat

A cat flap permits your pet to go and come as they please without you having to leave them to themselves. It can also stop draughts entering your home, which is not beneficial for you or your cat.

However, if you have a uPVC or composite door, it could be a challenge to put in the cat flap. These doors are constructed of different materials and the installation is different. Be sure to check with the manufacturer if the door is compatible before installing the cat flap on your uPVC composite or uPVC door. Changes to the door could be detrimental to warranties.

These doors are generally designed to be durable and tough with insulation. This makes them more resistant to weather elements than other types of doors, however they can be difficult to install the cat flap. If you're unsure about whether your uPVC or composite door can accommodate a cat flap, consult with a professional joiner prior to beginning.

You'll have to measure their height to ensure they pass through the door. This will be easiest when they're asleep or calm, so that they aren't moving around too often. Once you know their height, take a measurement of the distance between their stomach and the floor to determine where the bottom of the cat flap needs to be. Then, you can mark this position on the door.

When you use power tools to cut your composite or uPVC door, you will need be cautious. The act of drilling into metal can cause it to crack, especially in the case of toughened glass. It is recommended to hire an experienced glass installer to install a cat flap in the pane. This will stop the glass from becoming brittle or shattering. A glazier will also provide you with a circular hole to use for the flap for your cat, which is less likely to crack and is safer for your cat to use.

Cut the Hole

If not, you can make one yourself by using a piece of paper (tracing paper is ideal). If it doesn't, you could create your own by using a thin piece of paper (tracing papers are great). After the shape is drawn on the door you can then use a spirit level to ensure that the design is horizontal. This will allow your cat's flap to be properly seated in the door and prevent it from being in a position to slide open or closed.

Then, you can employ a jigsaw for cutting out the shape marked on the door. Use a blade that is specifically designed specifically for uPVC doors. It will typically be identified with this information. If not then ask the staff at your DIY store for help. Once you have the hole made then place the flap against it and then push it out to ensure that the flap's movement is smooth. If it binds on any points then make use of a file or a rasp to correct this.

Verify that there aren't gas or electric pipes inside the door you're planning to cut into. Your jigsaw could cause damage to 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 and be cautious not to scratch them during this process.

The majority of people who install a cat flap on their own will have an ordinary solid uPVC front door, so they won't be faced with these problems. However, if your door is made from wood or has a decorative panel that cannot be removed, it will add to the complexity of the task.

It is always worthwhile seeking assistance from an expert cat flap fitter when it comes to these types of jobs since it is important to get them done right to avoid potential problems in the future. If you do it wrong, it could cause the door to be damaged and may make it impossible to honor the warranty.

Install the Flap

Once you've made your hole, you can place the flap to see whether it opens and is able to fit. If you spot any areas that stick or catch, file them down with the aid of a hand file or sandpaper until it fits properly and opens without issue. Make sure that the flap sits in a flush position with the door.

If your kit doesn't have templates, you can use thin paper like tracing or acetate. Place the paper on the door and draw a line in order to indicate the location where the flap is placed (this will serve as your cutting guide). Then using the pencil lines you've drawn on the door, draw four screw holes in the corners of the flap - these will be the screw points you'll use to put it in the right position.

Most uPVC doors are strong and therefore simple to cut into. If your door is made of composite or GRP the process can be more difficult. If you're not comfortable with this, it's best to hire a professional. They should also be able to provide you with advice on whether or not your door is suitable for cat flap installation.

You can install an opening for a cat flap in composite doors, but it is important to check with the manufacturers or a professional joiner before you do so since any modifications to these types of doors may invalidate the warranty. If you decide to tackle the work yourself, keep in mind that it can be messy and may even be hazardous.


When you have composite doors, you'll typically need to use a grinder or saw to cut through the door panel itself rather than simply through the GRP.  cat flap installer  can be a dangerous job, and you will require extra care to ensure that the door is not damaged. It's also worth noting that cutting holes into any type of glass for a door is far more difficult than making the same changes in a uPVC or solid wood door.