Lois writes from Arizona: "In Tucson, for new residential construction of aerated concrete block (AAC) with a standing seam metal roof, do I need to paint a vapor barrier on the ceiling after insulating the attic? Should I use vapor barrier paint on interior drywall?"

Answer: That is a question your local building code official will need to answer. Vapor barrier use and placement various throughout the U.S. depending on humidity levels.