Vapor Barrier Attic Wall

I want to install insulation in my attic floor which i use for storage.

Vapor barrier attic wall.

Even though we apply vapor barriers to exterior insulated walls in cold climates it s no longer recommended for ceilings floor of the attic. To thwart the comments of the expense of the double wall headed my way i would like to add that the second wall that i add to the interior is totally non structural 24 o c. This wall assembly will dry from the vapor barrier inwards and will dry from the vapor barrier outwards. 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.

In any case the vapor barrier must point to the warm side. 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. 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.

Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Plastic specifically 6 mil polyethylene plastic is. Because it s nearly impossible to seal penetrations in the ceiling the reality is water vapor will get into the attic. Not every wall does.

Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. Some regions don t require a vapor barrier. Whether or not you need a vapor retarder hinges on three main factors.

Attic vapor barrier detail for cold climates. A vapor barrier reduces the movement of water vapor by. After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. The science of moisture movement.

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. 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. Thus installing vapor barriers on wall surfaces must.