Vapor Barrier Attic Wall

A vapor barrier s job is to keep water vapor in humid air from diffusing through one side of a wall and finding a cool surface inside the wall.

Vapor barrier attic wall.

Concrete block with interior frame wall cavity insulation and brick or stone veneer applicability limited to mixed humid hot humid mixed dry hot dry and marine regions should not be used in cold very cold and subarctic. Some regions don t require a vapor barrier. In any case the vapor barrier must point to the warm side. Water vapor can pass through building materials in several ways including direct transmission and by heat transfer but studies suggest that fully 98 percent of the moisture transfer through walls occurs through air gaps including cracks around electrical fixtures and outlets and gaps along baseboards.

The previous owner has 1 foam insulation with a a plastic vapor barrier only on the rafters of the roof about4 from the slate roof but not on the walls of the attic. Plastic specifically 6 mil polyethylene plastic is. 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. When a vapor barrier is on the side of a wall where the dry air is i e outside in winter or inside in summer moisture problems can occur.

Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic. I want to install insulation in my attic floor which i use for storage. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Attic vapor barrier detail for cold climates.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. The science of moisture movement. Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria.

My question is should iuse a vapor barrier inthe attic floor. A vapor barrier reduces the movement of water vapor by. Even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic. Not every wall does.

The few holes in this barrier required for exterior lights switches can be easily sealed with a can of foam or silicone mushroomed on both sides of the vapor barrier. Whether or not you need a vapor retarder hinges on three main factors. This barrier is meant to keep moisture from getting to the insulation in the walls and ceilings and it is required by building codes when insulating most houses.