John writes from Flushing, New York: "My cathedral style attic roof has R-30 insulation with paper style vapor barrier stapled to the studs. It has roof vents installed under the insulation. Some of the insulation is missing the vapor barrier. Can I cover all of the insulation with plastic to be sure it all has a vapor barrier? Is any other vapor barrier recommended?"

Answer: The entire assembly can be covered as long as the plastic material is in direct contact with the Kraft paper. As an extra precaution, my technical friends recommend cutting the Kraft paper with a razor blade before installing the plastic.