Pet Factsheets

Cat flaps

Fed up with playing doorman to your cat, without a tip? A cat flap could be the solution, allowing your cat free or designated access to the outside world.

Where can I put a cat flap?

A cat flap can be fitted to just about any door, wall or window. Wooden doors, walls and glass can require different types of cat flap, so make sure you choose one that is suitable. Cat flaps are normally used to allow your cat access to the house but an alternative is to fit one to a shed or outbuilding, so that your cat can shelter somewhere dry.

Glass doors or windows

Fitting cat flaps to glass doors or windows can be tricky and you should get a qualified glazier to do the job. If you have single glazed glass doors the glazier should be able to cut a circular or square hole for a cat flap. However all doors in modern buildings have to be fitted with safety glass. It is possible to fit cat flaps in double-glazed doors and safety glass, but the holes need to be cut when the glass is being made. Replacing all the glass in your door may be expensive, so see if it is possible to replace just the lower door panel with a piece of glass with a hole for the cat flap. Alternatively, since windows do not have to have safety glass, think about fitting a flap in a downstairs window, if your cat can easily obtain access to it, and there is a safe drop down on the other side.

Wooden or metal doors

If the cat flap is going to be positioned in a door, measure the thickness of the door and choose a suitable cat flap. A tunnel or inner liner will make neater finish in a wider door and usually tunnel extensions are available. Plastic cat flaps can be used in metal doors, but aluminium types are available and usually preferable. A cat flap should not be fitted to a fire door as the fire-retardant properties will be seriously altered. Measure the height from the floor to the belly of your cat, usually 100-150 mm (4-6 inches), and this is the height you should fit the cat flap.

Brick walls

Consult a builder if you want to fit a cat flap in a wall and choose a cat flap suitable for the thickness of the wall. The cat flap may need a tunnel, or another method, to connect the front and back parts.

What about security?

For security purposes, a cat flap should be fitted on the side of a door away from the handle, so that a burglar cannot put their hand through and reach the lock or key. A self-locking cat flap which can only be operated by your cat can help keep would-be feline, or human intruders out.

Will my cat use her new door?

Young cats usually learn to use their cat flaps very quickly. Older cats may find them confusing at first and need some training to use them. Before you fit the flap into the door/wall/window, allow your cat to investigate it. Try and encourage them through it with treats. When you first fit the cat flap, prop the flap permanently open and entice your cat to go through. Placing a bowl of their favourite food on the other side may do the trick! Once your cat is happy to go through the open hole, prop the flap slightly less open. Gradually lower the flap a bit at a time until eventually your cat is starting to push the flap just a little to get at their treat. Use plenty of praise as they begin to work the device on her own. If your cat is litter trained moving their litter tray outside the cat flap may make them go through once desperate, although this can be a high-risk strategy! Sometimes a catnip spray may help to attract your cat to the other side of the cat flap.

How do I keep unwanted visitors away?

Once you have a cat flap, you may be unwittingly inviting other cats to enter your home, which can cause a great deal of stress to your own cat. If your cat's behaviour alters, they begin to hide away, or start spraying urine inside the house after you have fitted a cat flap, this might be the cause. There are several types of cat flap that can only be opened by your own cat:

  • Electronic or magnetic flaps use a 'key' which your cat wears on her collar. The flap automatically unlocks when it recognises your cat approaching (even if this happens at speed). This will keep out all cats not wearing the magnetic key collars, but you could be unlucky and find that the invading cat has a similar collar of their own, as all 'keys' are the same.
  • Programmable key collar that uses an electronic password will only allow your cat to enter.
  •  Microchip cat flaps read your cat’s microchip and allow them entry whilst keeping others out. You can programme them to accept more than one microchip number, so they work well for multi-cat households as well as single.

Can I stop my cat coming in and out?

If you want to have control over your cat's movements in and out of your home, you can choose a locking cat flap which restricts access. The most simple of these are locking cat flaps which allow you to manually lock the flap closed to determine which side of the flap your cats stays. 

The more advanced four-way locking system uses out only, in only, fully open and fully locked settings. If you like your cat to come in at night, but don't want to wait up, then the in only setting will allow you to get to bed on time. Some cat flaps now include timer systems where the flap will lock, or allow in access only, at a set time, and then release again at another time. This function is very useful if you want your cats to stay in overnight but to have free access in and out in the daytime.

Can my cat be injured by a flap?

The flap is so light that it is unlikely to hurt a cat's tail, back or paws even when they fly through at great speed! For exceptionally acrobatic cats think about getting a flexible, rather than solid flap. Very large cats can get wedged in flaps whilst trying to get through, so consider buying a brand which offers a ‘large’ size flap if you think you need one.