Introduce your cat to the flap before it's set up so they can get used to the size and shape. Open the flap and let them explore it from all angles.
Ensure the cut-out is even and ensure that the cut-out is square and even. Mark the screw holes on your door and align them with the opening for the cat flap - the distance between the edges should be equal.

Preparation
Installing a cat flap in your home is beneficial to the health and well-being of your pet. It allows your pet to freely move from the inside to the outside, without needing to allow them to enter or leave. It can also prevent them from fighting over cat food, litter boxes, or the door of the home.
Prepare the area where you'll be installing your cat flap prior to when you begin. It will be easier to work if you remove any obstacles. It is also important to remove any furniture and decorations that may interfere with the installation.
You'll need to trace and measure the area where you'll be installing the cat flap. This will prevent you from making a mistake which could cause damage to your door or wall. You should put the cat flap in a spot that is easily accessible to your cats, but won't compromise your home's structural integrity.
The cat flap can be placed on the doorway leading to a locked space like your closet or laundry room. This will prevent your cat from jumping over it, and will protect your pets from dangers. The cat flap should be low enough for your smallest cat to use, since larger cats may have difficulty to jump through the flap.
It could be a good option to employ an experienced handyman if you have sliding doors or sash window that is old-fashioned. It isn't easy to install an animal flap on these doors and windows and any mistakes can cause costly damage. A professional can install the cat flap without causing damage to the structural strength.
You'll need to measure the height of your cat's belly from the ground to mark the area for the flap. This will allow you to precisely cut the flap's opening. Once you have the line marked with a spirit-level, use it to ensure it is completely horizontal. Follow the directions that came along with the cat flap kit to find the template drawing. Attach the template to your door, so that the bottom edge coincides with the horizontal lines you have drawn. The template should be centered at the middle of your door.
Measurement
A cat flap, sometimes referred to as pet door is a small opening in the bottom of your exterior doors or windows that allow pets to leave and enter the house. They are available in various sizes and materials so that you can choose the best one for your home and pets.
Before you buy a cat flap it's important to accurately measure the dimensions of your windows or doors in which you plan to install it. This way, you can ensure that the hole is going to be of the correct size and that the cat flap will fit. One method is to block off a portion of the door, and then try to walk through with your pet. This will give you an exact picture of the opening size (width).
It is also recommended to measure the height of your cat from the ground up to the lowest part of their stomach. This will ensure that the flap is placed at a height where your cats are at ease. If it's too low, they may struggle to pass through. If it's too high, they may not be capable of using the flap.
In general, you should strive to make your holes at a 45-degree angle to the vertical surface. This will result in the most stable and secure fixings for the installation of your cat flap. Ideally you should use a spirit-level to aid you in this, but if the directions included with your cat flap kit don't include this feature, a straight edge will do the same job.
It is best to employ an experienced glazier install the cat flap on a UPVC or glass door or window. These doors are usually toughened, and drilling can cause damage to their structure and lead to them shattering. This could pose an security risk to your home.
Placing a cat flap in brick walls can be problematic too, as drilling into a soft area of the wall this can create problems for cables and pipes that run through the property. This can lead expensive repairs and leaks, as well as weather damage that comes from outside.
Marking
After you've measured your cat kitten to determine the appropriate size flap, it's time to mark the location where the hole will be. Mark the centre of the flap using your spirit level. If the template for your cat flap kit does not include a centre line, photocopy it and trace around it using a pencil to mark the spot where the hole must be cut.
Remember, if the cat flap is too low, it could make it difficult for your cat to get in and out of the house, and if it's too high, they might struggle to see what is happening outside. To ensure your cat feels at ease and secure, it is best to put the flap as close as possible to their stomach.
It is essential to keep a cat flap from being too close to a solid wall frame. This could result in problems with damp and draughts. If you're not familiar working with masonry it may be worth seeking professional help.
Then, prop open the door and show your cat or kitten where to go. ( replacement upvc door panel with cat flap is helpful if someone is inside, to encourage them). Once they've made it through it then you can gradually begin to allow them to enter and exit at will.
It is important not to push your cat or kitten through the flap too quickly as this could cause them to be scared. The clunk and snap squeak of the door closing may cause harm to your cat or kitten. They will be even more scared if their tail is caught in the flap. Cats are also known to return home to check for intruders, and leaving the door open can be dangerous. Your pet may be attacked by another cat they are familiar with. This is why it's best to install a small cat flap and only if your cat is aware of its use.
Installation
Once the flap is in place It is essential to teach your cat to use it. It may take some time but with patience and some treats to encourage them to learn, they will eventually get the grasp of it. You may also want to put a lock in the flap for extra security, particularly during harsh weather conditions or when away from the house.
The first thing you need to decide where you want to place the cat flap on your door. It must be placed in a place that opens up into an area that is protected from the elements of your garden. This will make your cat feel more secure as they go into and out of the house, and also to keep other animals from entering your home.
Also, you should consider the height of the cat flap. This should be in line with the measurement of your cat's stomach to ensure that they can move through. You can also place steps on either side of the entrance to help your cat pass through.
Once you've decided on where you'd like to place the cat flap then you can measure the door with a pencil and mark the spot. This will give you an idea of the best place to cut. The next step is to cut a square in the door with the Jigsaw. It is recommended to wear safety glasses and a mask for dust protection while doing this, as breathing in dust can be dangerous to your health. After the square has been cut then sand the edges the door. This will give an even edge.
After you've finished sanding your door, you can replace the cat flap. The flap should be installed so that the lock, if it has one, is on the inside of the door. If there are screws for the cat flap on the door, now drill them into the hole. Then, carefully insert the flap into the hole. Make sure it fits snugly.