A year ago last March I lost an outside cat to either a car or a coyote. So I decided to screen in the back porch when I got a new kitty. My porch only had three support posts, so my son and I bought 4x4s and 2x4s and built a frame, including a screen door. Then instead of using window screen because it can tear if the cats climb up it, I went to Home Depot and bought green flexible plastic screening that fit perfect between the 2x4s. We just stapled the plastic to the boards and they can climb it without tearing it. The older cat was not happy about being confined, but has learned to live with it. I also bought 1x8s and stapled carpet scraps to it and made them a ledge. They spend all day out there except during the hot (100+) afternoons.