Vapor Barrier Against Concrete Wall

Most jurisdictions require a 4 mil plastic sheet vapor barrier for basement walls against concrete.

Vapor barrier against concrete wall.

Or you can leave a 4 inch gap between the studs and concrete wall and probably get away with it. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. A vapor barrier against the concrete surface is generally recommended before wood framing or flooring materials are installed. The water vapor can come through the concrete from the soil or from indoor air that comes in contact with the concrete.

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. So there is enough gap for air to flow. Below grade walls and floor slabs transmit ground moisture through concrete walls or slabs. Of foam against the wall this should not be a problem in your climate.

With fiber insulation and a vapor barrier moisture can get trapped in the insulation leading to moldy insulation and decay in the wood framing. Vapor barriers are used because while fresh concrete is poured wet it s not supposed to stay that way. In any case the vapor barrier must point to the warm side. The gasket must be designed specifically for use with.

Building codes usually require a vapor barrier 4 mil plastic sheeting on exterior basement walls if the framing is attached to masonry or concrete surfaces or if the wood framing butts up against the outer basement walls. Lay a continuous layer of 1 4 inch foam gasket or similar moisture and air barrier on top of the concrete slab before applying sill plates. Crawl spaces benefit from a polyethylene moisture barrier placed directly over the exposed earth. You should then use fiberglass insulation that has a vapor barrier between the studs with the vapor barrier facing in toward the living space.

A concrete vapor barrier is any material that prevents moisture from entering a concrete slab.