Vapor Barrier Roof Hot Humid Climate

The inner surface in colder climates and the outer surface in hot humid climates.

Vapor barrier roof hot humid climate.

Even vinyl wall paper which has a low perm rating can induce moisture problems in warm humid climates where hot moist conditions tend to drive moisture into the wall from the outside of the building. In cold climates condensation is limited on the interior side of the vapor barrier as a result of installing all of the thermal insulation on the exterior side of the vapor barrier which is also the drainage plane and air barrier in this assembly. When constructing unvented roofs with asphalt shingles in hot humid climates a vapor barrier must be installed between the asphalt shingles and the roof deck. Vapor barriers are usually best installed on the side of the wall that experiences the hotter temperature and moister conditions.

In cold climates the location of the retarder is to the interior side of the thermal insulation. Classic hot humid climate wall assembly. The vapor retarder location specified above is specifically for hot humid climates. In very warm humid climates if a vapor retarder is used naima recommends installing it to the exterior side of the wall.

Therefore the ideal assembly of a frame wall keeps the interior side fully permeable and locates both an air barrier and water vapor retarder or barrier to the exterior side to minimize the entry of outside water vapor. In hot humid climates the design location and installation of the air and weather barriers are more critical than for the vapor retarder.