I know this an older thread but wondering what you ended up with? My coop is on an overgrown concrete pad. There were a lot of rain/flooding issues. We had ran a 2x4 treated edge to the bottom of the coop and I filled with the wood chips from an old cattle stall in our barn. This has worked so far( just put the chips in on Sunday) and we have had not just rain but storms on top of storms . I also added old 4x4 from the structure we rebuilt on the outside perimeter. I believe our next step is to hang some greenhouse grade plastic sheets from the corner that seems to get hit the most.
