Vapor Barrier Walls Concrete

To know if you need a vapor retarder ask yourself a few basic questions.

Vapor barrier walls concrete.

Vapor barriers are used because while fresh concrete is poured wet it s not supposed to stay that way. A concrete vapor barrier is any material that prevents moisture from entering a concrete slab. It needs to dry and then stay dryto avoid flooring problems. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

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. 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. Thus vapor barriers are also.

While current practices versus old methods are under some debate the rule of thumb is that a vapor barrier is installed on the warm side of the insulation in a wall. If you have a framed wall that is adjacent to a concrete foundation wall where the vapor barrier is next to the drywall in front of the studs the fiberglass insulation gets wet and becomes a breeding ground for mold.