https://squareblogs.net/tubmal....let3/cat-flap-instal
A through-wall cat flap lets your pets come out and in as they please. But, you should be careful not to place it too high in the wall. This can result in energy loss and allow burglars to enter your home. A hole in a cavity can also be a problem for future owners if you intend to sell your home. Cat doors made of glass are a safer alternative. Easy to install A through wall cat flap is a great way to let your cat come and go whenever it wants. There are numerous models available and they are easy to install. Some allow you