All the instructions I've read say to install hardibacker on "exterior grade plywood". I didn't use exterior grade plywood, but I do have a solid 3/4" plywood sub floor. Do I need to pull up my sub floor? Should I prime with exterior grade primer and paint it instead? Do I really not need to worry? Does the moisture in the thinset soak into the plywood? I want to do it properly but I really don't want to pull up my plywood.
Ian