Vapour Barrier Exterior 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.

Vapour barrier exterior wall.

Below grade walls and floor slabs transmit ground moisture through concrete walls or slabs. 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. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. 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.

Whether or not you need a vapor retarder hinges on three main factors your climate your home and the location of the wall you re insulating. Any condensation on a properly installed continuous plastic vapor barrier will. Very hot and humid climates may benefit from an exterior vapor barrier that keeps outside humidity from penetrating into walls. Vapor barriers are applied to the interior walls in climates which are predominantly cold while they are best applied to exterior wells in predominantly hot climates.

A continuous plastic vapor barrier prevents condensation from forming on the internal surfaces of the exterior wall. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter. To know if you need a vapor retarder ask yourself a few basic questions. 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 wall assembly will dry from the vapor barrier inwards and will dry from the vapor barrier outwards. In any case the vapor barrier must point to the warm side. A vapor barrier against the concrete surface is generally recommended before wood framing or flooring materials are installed.