When we built the catio almost six years ago, we set up a window as the access point. To keep the flies out I cut a cat flap in the screen (because window screens are relatively easy to fix). Well, this is fantastic in the summer, but in the winter it gets a bit chilly in the living room. I had been using a scrap piece of clear plastic to block some of the incoming draft, but it was getting old and brittle so I ordered a larger piece. With a larger piece I was able to cover the whole screen and cut a new cat flap.

I cut the plastic to size and adhered it to the screen frame with glue dots. I then put it back into the window. It took the cats a couple days to really get used to it, but it makes a huge difference reducing the winter breeze through the room.