https://mozillabd.science/wiki/Doors_With_Cat_Flap
Installing a cat flap on your door is a relatively simple task. You will need to be aware of a few things prior to getting started. It is possible to install upvc panels with the cat door without cutting the door or wall. Many glass companies provide them with holes already cut to fit the purpose of a pet-door. 1. Safety Cat flaps made of upvc are simple to install and can be fitted to many different kinds of doors. They are energy efficient and weatherproof and come with an integrated draft excluder that helps to insulate the opening.