My hens have large shade trees in their yard and they burrow down into the cool soil in the shade when it gets real hot. The chicks I got this spring have NO shade in their yard from about 2 to 5 pm. I bought a dog kennel shade, 10 feet square, and put it up on a frame. It only gives 70% shade, so under it I put a large plastic doghouse roof up on 4 x 4 stilts about 2 feet high for good air circulation under it. I put their feed and water under this, which also protects it from the rain.
The little chicks gather round under this when they lose their shade from the barn. I've noticed that the shadows are moving now as the sun goes back south, so I don't think it will be a problem much longer.
To whoever said their back yard looks like a homeless chicken shantytown, mine does too! Fortunately, no one can see it but me.
My first coop is beautiful, but there was no room for more hens, so the stuff I've rigged up for the baby chicks is the problem. I built their coop right inside the barn, but it gets very hot in there in the afternoon, so they are not spending any time in there.