Vapor Barrier

Vapor Barrier

Where humidity is not a problem, the vapor barrier is installed on the warm side of the wall. During the winter, water vapor is blocked from penetrating the insulation and condensing on a cold outside surface. Where humidity is high in the summer and air conditioning is used, a vapor barrier is recommended on both sides of the exterior wall. During the winter, the interior vapor barrier prevents water vapor from penetrating the insulation and condensing on a cold surface. During the summer, the exterior vapor barrier can prevent water vapor from penetrating the insulation from the outside and condensing on a cold air conditioned surface on the inside of the wall.