We've got an 8x6 shed that we have kitted out for the hens. Currently have 23 in there with space on the perches for more, plenty of room to jump down as well, and of course space for the nest boxes. It's really easy to clean out too because you can actually get in and stand up. I have a few smaller coops for broody hens, quarantine and younger chicks/hens not yet ready to join the main flock, I much prefer the shed for cleaning out. I can do a much better job in less time.
Dans