http://brewwiki.win/wiki/Post:....Cat_Flap_Installatio
A cat flap allows you to give your pet more freedom while avoiding the headache of having to let them in and out. It will also make your pet less stressed and stop them from coming into the home when they're not welcome. To set up a cat flap to install a cat flap, measure the distance from the bottom of the cat's stomach to the floor. Draw a line along the door panel. Check that the line is level with the spirit level. 1. The kind of door If you're installing a cat flap into the uPVC door panel or double glazing glass sealed unit