We are considering a steel building to retrofit for a coop, either this Or, possibly a more regular type but it will be large enough to replace all the coops plus have storage for all waterers, feeders, hay, etc., maybe even an office room, in the building. My question, especially with the first one is about the floor. We don't really want concrete because of possible leg injury to the birds, not to mention added expense, and don't really want just dirt because I can't figure how to keep rats from tunneling inside. If anyone has done one of these, what did you do for the floor? We are thinking about sand, but how, exactly? Over wire mesh and dirt? Having trouble figuring the floor issue.