Attic Insulation Vapor Barrier Direction

The purpose of insulation facing the facing on kraft faced insulation is made of kraft paper with an asphalt coating that makes the paper impermeable to water vapor.

Attic insulation vapor barrier direction. The paper creates a vapor barrier that helps keep the water vapor in the warm moist heated indoor air from migrating outward into the wall or other structure. Never compress or fluff your insulation. Also on the graph is the permeance of polyethylene. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

The placement of the vapor barrier depends largely on the climate where your house is. Not so asphalt saturated kraft paper. The best approach for a vented attic in a cold climate is installing a layer of drywall with a good coat of latex paint the paint creates a semi permeable vapor barrier. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below.

Vapor barriers in attics should only be installed on one side of the insulation. This acts as a barrier to keep heated moist air from rising up into the attic during cold weather. Not every wall does. If you put it on the right side where the humidity is it s not much of a vapor retarder.

Joe says in the article plastic vapor barriers really are vapor barriers when things get wet. If the insulation is installed with the paper vapor barrier facing away from the heated part of the home moisture from humid inside air can condense and become trapped in the insulation during cold winter months. In warm climates the barrier should point to the outside of the house blocking the vapor from the humid outside air that may seep into the walls or ceilings. Adding a second vapor barrier could cause condensation to become trapped in the insulation between the two vapor barriers.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. Not be trapped inside. Attic insulation should always be installed with the paper backing facing toward the living space the ceiling in this case.