My floors in both my bathrooms in my mobile are completely caving in. I cannot afford to pay someone to come and fix them, and all the web sites I've checked out only tell me how to put new plywood over the pre existing floor. If my floors are almost gone how can I achieve this goal? I just want to know how to lay down brand new plywood but I need a step by step guide on how to do it. Where can I find this kind of guide for free?