- Q.Will a vapor retarder be
effective on the walls if there is no retarder in the
ceiling?
A.A vapor retarder and
air barrier will keep the moisture in the living
area from being pushed into the wall cavities.
While it would be better if there was a vapor
retarder in the ceiling as well, it is much easier
to ventilate the attic to avoid moisture problems
than to remove moisture from the wall
cavities.