My husband and I are new to rising chickens; will be getting three hens in about 3 months from a friend. We are looking at coop designs. He thinks a portable coop and run (about 90 lbs.) are the way to go as the chickens will have grass to eat daily (until the snow falls) and they can be moved closer to the house when it gets cold out. I haven't seen any designs so far that really support this. Everything I've looked at seems quite permanent. My thought is that the chickens need a more permanent surface for their run with sand for scratching, etc. Any advise?