https://fkwiki.win/wiki/Post:H....ow_to_Install_a_UPVC
It is possible to insert a cat flap into an upvc panel or double glazing sealed unit. However, the most effective alternative is to install an entirely new glass pane that has a hole that is already made. Take note of the instructions that will be provided with the kit for cat flaps, and follow them with care. Make sure that the template sketch accurately depicts the shape (circle or square). Safety If you have a dog or cat and would like to let them in the garden without having the door open A microchip activated