Attic Insulation Ceiling Vapor Barrier

Not every wall does.

Attic insulation ceiling vapor barrier.

If you live in a cold climate place the vapor barrier between the interior of your home and the insulation. This acts as a barrier to keep heated moist air from rising up into the attic during cold weather. Whether using loose fill or batts put the vapor barrier closest to the warm side of your installation where hot moist air would get in facing the house s interior in cold climates beneath floor insulation and the attic s interior in hot climates on top of floor insulation. Before the introduction of attic insulation attics in cold climates were poorly insulated and plastic ceiling vapor barriers were omitted.

In any case the vapor barrier must point to the warm side. The insulation fiberglass or cellulose is then placed on top of the drywall with no vapor barrier above or below. When adding additional insulation to an attic that is already insulated never use insulation with a vapor barrier. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. If you live in a hot humid climate place the vapor barrier toward the outside of the wall cavity. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Now with attic insulation heat is no longer lost from the living space such that.

A vapor barrier in an attic assembly in a severely cold climate with the absence of an air barrier will likely be ineffective. The heat being lost from the house below warmed up the attic so that moisture was lost through the vents as vapor. Some regions don t require a vapor barrier. If you do there is a chance that moisture that has slipped by the first vapor barrier will become trapped by the second vapor barrier decreasing the value of your insulation.

On the other hand an air barrier a properly detailed air tight drywall ceiling for example in the absence of a vapor barrier can be effective since it stops the flow of vapor laden air. Whether your vapor barrier is a facing or a film it must be placed on the warm in winter side of the wall.