I've seen other threads about this, but I'd like feedback on my solution. I purchased 23/32 tongue and groove OSB panels for the coop floor and have them about halfway installed; it's what my construction book said is good (for houses...). I was vaguely aware of moisture issues, but figured we'd just seal it. Now, though, I'm having my doubts. I spent way too much time last night searching for methods to seal OSB in general and chicken coops in particular--Answer seems to be that it was really pretty dumb of me not to spring for the extra $5 a sheet for plywood, and that the OSB will either last ten years untreated or disintegrate within a year no matter what I do (thanks internet). We are way overdue in making the coop, so I don't want to undo the floor that is already done (nevermind the money issue), but I'd like to do what I can to maximize our chances of it lasting an ok amount of time. I really hope this hasn't ruined the whole thing! OSB subfloor I purchased is: http://www.homedepot.com/p/23-32-in-4-ft-x-8-ft-T-G-Premium-Subflooring-486701/203169027 Constraints/considerations: (1) Coop is 8'x10' elevated 1.5'-2.5' above ground (slope), we plan to do deep litter (2) Solution preferably under $50, could go up to $100 if it's really good (3) No vinyl (may be ok, but other sources seem to say it can be toxic; we don't want to take chances) My current plan is to seal the cut edges of OSB (with waterproofing?) before constructing further (I should be able to reach these even in the parts I've already laid), build the rest of the coop, then cover the interior floor with 7/32 plywood underlayment (maybe with vapor barrier?), and paint and waterproof the floor (and the rest of the coop), sealing/caulking the edges. I am also considering painting/sealing the outside bottom of the coop (not sure how much this helps or whether it is worth the time/effort to do so). Thanks for your help!