We've torn out the wallboard around the tub and are going to replace it with cement board and tile. I know we are supposed to put a vapor barrier over the cement board. But here's my question - one of the walls is an exterior wall, which has paper backed insulation in it. Do we put the vapor barrier on top of this as well? I thought a double vapor barrier was problematic, moisture condensations, etc. So should I leave that wall without the new barrier? Oh, and another issue, when ripping out the old wallboard, we tore some of the paper backing so now its not really air tight. I guess I could just tape over the tears, but still not sure about the double vapor barrier thing.