Hi, all, I'm heading into the home stretch with the coop, but I have a question that the mighty Google has not helped me to solve. I'm putting Ondura corrugated plastic roofing on the coop, and while their website told me all kinds of useful things about purlin spacing and nails and panel storage, I need to know what size wood to use for the purlins! Here's the coop: It's 4 x 6, but with the slope and the extra overhangs to keep the rain off me the actual depth of the roof will be 6 feet 4 inches x 6 ft 4" wide. The coop itself is framed with 2 x 3s except for under the deck, which is 2 x 4s. Edited to add-- it's way off center on the deck right now because it's not attached yet, so we can carry it into place without extra help. It actually lines up right! Purlins look skinnier than framing in the illustrations, but I can't tell how much smaller. Any thoughts? Thanks!