i am rebuilding a basement bathroom from the frameing up. In the new shower & room walls should i be putting some type of plastic on the frameing before wallboard or hardibacker. i have 1 small window and no fan. i asked this question in the plumbing forum and some links were suggested but they did not answer this question. i have heard "yes" it's needed and I've heard it makes things worse. any ideas? thanks, j.