https://imoodle.win/wiki/Cat_Flap_Double_Glazing
It is possible to install an animal flap into the door panel made of upvc or double glazing glass sealed units but the best solution is to purchase a brand new glass pane that has an already-made hole. Follow the directions that should be included with your cat flap kit and follow them with care. Make sure that the shape you have drawn (be it square or circle) is accurately drawn on the template. Safety If you have a dog or cat and want to allow them access to the garden without having the door open, a microchip activated pet flap in you