Here are some of the options when installing dog and cat flaps into double-glazed glass units and patio doors with UPVC or Aluminium Frames.

Pet doors through doors can save space and provide a natural flow of pets and people in and out of the property. There is a range of doors suitable for installation into a double-glazed unit that includes manual infrared and microchip doors.

To instal a pet door in the glass you will normally need a new double-glazed unit manufactured you can employ a fitter to come and measure the existing glass unit and then return with the glass unit that is manufactured with a hole in it to accept the new pet door or you can organise this yourself.

Please note your existing glass is toughened and as such it's not possible to cut a new hole through the door.

To order a replacement unit some information is required and this will involve removing the beads in your existing door or window. Beads come in many variations so you will need to work out how to remove them. 

Once the beads are out you can measure the existing glass unit there are three sizes required height width and depth of thickness. 

Double-glazed units mainly come in 20mm 24mm or 28mm thickness triple glazed comes in 44mm there are other sizes. There is a fourth measurement required this involves working out the diameter of the hole required and what height you want it to be, bearing in mind the overall width of the cat flap or adapter will need to be above the top of your glazing bead.

Once you have these sizes you can order your double-glazed unit from a local manufacturer.

An alternative which is also worth considering if you have a half-glass door is to replace the bottom glass panel with a UPVC panel. The process for ordering is similar you need to know the thickness. These half panels can come with ply reinforcing which makes it easier to instal the cat flap.

Patio sliding doors are the same as above but the glass panels are normally a lot bigger the PetSafe 270 or 280 are designed to be used with sliding doors.

There are some small doors for dogs that can be installed in the glass but most dog doors will need to go into a UPVC panel.