Exterior Wall Vapor Barrier

What s more on uninsulated houses that didn t have air conditioning a vapor barrier was not needed.

Exterior wall vapor barrier. This wall assembly will dry from the vapor barrier inwards and will dry from the vapor barrier outwards. Dupont tyvek drainwrap is a moisture barrier designed to provide enhanced drainage in areas subject to extreme wind driven rain. 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 barriers are sheets of plastic or other material placed on one side of insulation sheets.

Window door openings connect both walls with 1 2 underlayment plywood and are sealed to the vapor retarder air barrier. In hot climates any moisture that condenses on the exterior side of the vapor barrier will be drained to the exterior since the vapor barrier is also a drainage plane. In exterior walls that are below grade like basement walls. 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.

It combines the superior air and water resistance vapor permeability and strength of tyvek with a vertically grooved surface to help channel water safely to the outside. The air circulation in the empty exterior wall cavity allowed any liquid water to evaporate and become a gas once again where it couldn t cause rot mildew or mold. A vapor barrier reduces the movement of water vapor by. Vapor retarder use and placement in certain climates vapor retarders can be a vital part of the wall construction.

Such a wall system can be built with multiple thermal breaks with the weakest areas having an. The exterior face of the wall or floor cavity should remain permeable in order to allow dissipation of any moisture that does enter the wall cavity. In any case the vapor barrier must point to the warm side. The standard installation of a plastic vapor barrier is between the studs and the drywall but there are some exceptions to this.

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. 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. This is then followed by a 2x4 wall with studs offset from exterior wall another 3 1 2 fiberglass or rockwool then sheetrock. If you are adding an exterior wall anywhere in the house and you answered yes to either of the above questions you should consider using a vapor retarder.