Basement Wall Vapor Barrier

So we thought it might be a good idea to clear up some of the confusion.

Basement wall vapor barrier.

For reference my basement is currently finished with concrete exterior walls then charcoal colored wrap material there seems to be an inch or two between this wrap and the exterior walls then stud framing with r12 batt insulation between the studs then a vapor barrier and finally drywall on top of the vapor barrier. 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. Polyurethane sheeting is a typical vapor barrier that contractors use to prevent moisture from penetrating the walls of a basement. We ve written several articles about basement insulation and a cost effective approach to basement insulation using foam board and fiberglass insulation since writing those articles we ve received quite a few questions about when to use a basement vapor barrier and when not to.

Not to be confused with a vapor barrier which is placed on the warm side of the wall just in front of the insulation and behind the drywall a moisture barrier goes against the basement wall. Whether or not you need a vapor retarder hinges on three main factors. Water vapor can pass through building materials in several ways including direct transmission and by heat transfer but studies suggest that fully 98 percent of the moisture transfer through walls occurs through air gaps including cracks around electrical fixtures and outlets and gaps along baseboards. A basement vapor or moisture barrier is installed during the new construction of a home or the remodeling of a basement.

The main concerns are condensation and drying potential. The science of moisture movement. The other option is to set the 2 4 wall framing in 4 from the masonry or concrete basement walls and use just the vapor barrier on the insulation facing toward the living space. The construction of the wall for instance is vital to the use of a vapor barrier.

Also be sure to use treated lumber for the bottom plate on the wall framing. When the mold grows it will spread to. In winter the dew point of the interior air is typically about 50 f assuming an air temperature of 70 f and a relative humidity of 50. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

Basement vapor barrier and insulation. Not every wall does. Thus installing vapor barriers on wall surfaces must.