I'm putting in a small bathroom in Arizona upstairs as part of an apartment. The plumber will lay the pipe on the existing floor proped too create proper slope to main drainage then we will build an elevated floor over. Basically you'll step up eight inches into bathroom from the rest of apartment. Then we will put subfloor on top then lay click lock vinyle planks that have attached underlayment.
First the floor that pipes will lay on is actually osb. Do I need to put something over the osb wood or paint kilz or something for proper moisture protection even though the pipes under that elevated floor will not create moisture. Then does the elevated subfloor that the toilet, sink, and shower rest on with the click lock vinyle planks need to be osb or plywood or what? AND should I seal with some sort of kilz before putting clicklock vinyle planks?