https://blogfreely.net/chiveve....st06/cat-flap-instal
https://squareblogs.net/amount....shrine47/installing-
Installing a cat flap on your door's panel is an important task that should be carried out by an expert. The doors are typically made of a thin plastic exterior that is bonded to an insulation-enhancing, soft polystyrene base. These materials can be hard to cut. It is a lot easier to fit the cat flap inside an existing glass pane or to make the hole for a new door. A glazier will be in a position to assist you. Easy to Fit Upvc door panels