Mine think they can fly but they are pretty spastic about it. I do keep an old blanket over top of their playpen "just in case".
Today my handyman came over and we've made a plan for the permanent coop! Ordering a load of sand.... He'll level the existing floor, then lay down a layer of wire that covers the entire floor, plus bend upwards about a foot around the edges. Then we'll add the sand on top of that wire. The bottom all the way around will be metal siding, trenched in. North wall is totally protected, South wall will be framed, and include a full size people door, but be mostly hardware cloth. East wall is existing solid wall about 4' tall, the rest will be done with stout wire panels for strength, then hex cloth inside of that for critter proofing. Similar approach for the ceiling.
The West call is currently solid, will be cutting a chicken sized door in since their big grassy run will be on the other side. I'm thinking about 20' by 65". (using part of a horse turn out area, just need one more fence line).
Love it when a plan starts coming together. I can see that one day these chickens will not be as high maintenance, once I have carefully built everything they need.