im re doing the bathroom, and need to know where i should put the vapour barrier . the outside wall has been re insulated with plastic backed unsulation . i would assume that that,s ok for the outside wall do i have to do the ceiling also ? and what about the other walls ? the home is a bi level so there is only the attic above the bathroom , wich does get very cold in the winter . i am sheetrocking the entire bathroom with the exception of the tub ceround , i will use concrete board an tile . the rest will be with a new product dense armour sheetrock.
i also will install a shower vent / light with around 130 cfm .
A vapor retarder should always go to the warm in winter side of the wall (or ceiling) and be placed as close to the finish surface of the wall as is possible. If you live somewhere that requires heating in winter, then the vapor retarder should be directly behind the drywall. If you have insulated with something that has a plastic surface, you may already have a vapor retarder. Do NOT install a second vapor retarder over the first.