House Wrap As Vapor Barrier For External Concrete Walls

Dupont tyvek homewrap is the original house wrap incorporating unique material science that helps keep air and water out while letting water vapor escape.

House wrap as vapor barrier for external concrete walls.

Below grade walls and floor slabs transmit ground moisture through concrete walls or slabs. While house wrap is water resistant it typically is not water impermeable or waterproof with good reason. In hot humid climates the cool side of the wall is the inside of the home that s got air conditioning operating. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

Whether or not you need a vapor retarder hinges on three main factors. Vapor barriers are put on the inside face of wall studs in cold climates and they re put on the exterior of homes in hot and humid climates. You want the vapor barrier as far away from the cooler wall surface as possible. Above grade exterior walls with semipermeable exterior finishes like brick over oriented strand board sheathing require the placement of an additional vapor barrier on the exterior side of the.

R703 1 1 the exterior wall envelope shall be designed and constructed in a manner that prevents the accumulation of water within the wall assembly by providing a water resistant barrier behind the exterior cladding and a means of draining to the exterior water that penetrates the exterior cladding r703 2 water resistive barrier. A vapor barrier against the concrete surface is generally recommended before wood framing or flooring materials are installed. Moisture will find its way into these wall systems by way of cracked mortar joints gaps or cracks in the surface of the material. Polywall blue barrier liquid wrap 2300 is a spray applied fully adhered permeable air and moisture building envelope protection membrane developed utilizing the latest in silyl terminated polyether technology stpe.

After the insulation is in place you will want to add a vapor retarder sometimes called a vapor barrier if you need one. This thin mil seamless substrate coating can be applied with an approved airless sprayer power rolled or hand rolled. The purpose of using house wrap is to prevent the entry of moisture into the wall cavity from outside. Very hot and humid climates may benefit from an exterior vapor barrier that keeps outside humidity from penetrating into walls.

As a result it can contribute to improved building durability by helping to protect homes against damaging wind and rain that can penetrate the exterior cladding.