Hi, I am new to BYC, but have been browsing around for quite a while. Well, our first ever chicks will be arriving soon and construction of our 8x8 coop is finally underway! My design will have an 8x8 coop with a "tree fort" above the coop. (e have two young boys and they are doubly excited about the chickens & the tree fort.) So, this means the coop roof itself will be flat, because it will be the fort floor, but the fort roof above will be sloped and it will be very weather resistant, if not weather-proof. The Coop & fort walls will continue all the way up and will be T-111. After all that long-winded typing, my question is.... Do you think a plywood coop roof/fort floor will be fine, or should I add some roofing underlayment, and maybe even another layer of plywood to make a sandwich? Is that over-kill? I do plan to seal the floor and T-111. The "Fort Coop" is fairly well protected by the elements, as it is partially under some pine trees. Thanks for all the advice and ideas!