A concrete vapor barrier is any material that prevents moisture from entering a concrete slab.
Vapor barrier walls concrete.
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.
Vapor barriers are used because while fresh concrete is poured wet it s not supposed to stay that way.
It needs to dry and then stay dryto avoid flooring problems.
A concrete vapor barrier is simply a sheet of polyethylene plastic visqueen placed directly on top of the sub grade before the concrete floor or slab is poured to help keep moisture from the soil from passing up through the concrete.
Very hot and humid climates may benefit from an exterior vapor barrier that keeps outside humidity from penetrating into walls.
The construction of the wall for instance is vital to the use of a vapor barrier.
Thus vapor barriers are also.
A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.
Below grade walls and floor slabs transmit ground moisture through concrete walls or slabs.
To know if you need a vapor retarder ask yourself a few basic questions.