I'm in the process of building my first coop. After reading a lot about materials and comparing cost vs performance, I decided to use OSB for the walls, and no siding. I read that it was comparable to plywood in every way, but much cheaper. I read about people using it on coops and recommending it. I was planning on painting all sides of the OSB (and the edges) with BEHR Premium Waterproofing Stain and Sealer. It's advertised as performing better than paint, because it absorbs into the wood and protects it better, as opposed to sitting on top of it like paint and peeling/chipping eventually. I'll caulk the seams between the OSB boards, too. Now, I was feeling all good and accomplished with my plan, and then I happened upon some threads on here and another forum saying that I shouldn't use OSB for exterior-facing walls at all... that it's gonna warp, mold and fall apart... and I'm having serious doubts. To be fair, the most critical thread was very old - from 8 years ago - so who knows, maybe they make OSB better these days? Also, people criticizing it are saying that it won't last long untreated, but they don't seem to take into account treated (painted/sealed) OSB. I found other comments from other folks who have used OSB, painted it well, and it's been doing fine. I already bought all my boards and stain and everything... Please tell me your honest and, ideally, experience-based opinion! Given my plan to seal it well, do you think OSB could work? The coop will be raised off the ground sitting on cinder blocks, there will be no wet tall grass or shrubs around it. The roof will have metal roofing panels on top of an OSB roof board (with a tar paper underlayment) and will have 6 inch roof overhangs, and every surface of OSB everywhere will be sealed.