Double glazing can be fitted with cat and dog flaps that allow your pet to come and leave at their own pace. These are also great to keep your pet's attention while you're away. You can install a cat flap in an existing uPVC or double glazing sealed unit. But, https://catflapinstallersnearme83050.shotblogs.com/installing-a-cat-flap-in-a-upvc-door-cost-44803398