I would like to know if it is necessary to have a vapor barrier with blown in insulation? In my 2yr old house it has blown insulation but no vapor barrier is this ok? Also I would like to add some insulaiton to it and am considering owens corning polywrapped insulation. Would it be ok to use this over the blown in? The product says its unfaced but is wrapped in plastic so I wasn't sure if I would have a problem with doing that. I currently have some layed out over my garage which is not insulated should I remove it and add some faced insulation instead or is ok to leave there without a vapor barrier?