Plastic Vapor Barrier Basement Walls

A vapor barrier is also helpful to keeping a basement insulated and warm.

Plastic vapor barrier basement walls. You should then use fiberglass insulation that has a vapor barrier between the studs with the vapor barrier facing in toward the living space. In exterior walls that are below grade like basement walls. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. 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.

When the mold grows it will spread to everything around it studs drywall etc. In any case the vapor barrier must point to the warm side. In very cold climates the use of polyethylene plastic vapor barriers between insulation and interior wallboard may be beneficial provided all air gaps into any wall and ceiling cavities are also blocked. If water vapor diffuses or infiltrates into the wall cavity and finds the cool surface moisture problems can occur.

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. The cool surface is the sheathing assuming no exterior insulation. The construction of the wall for instance is vital to the use of a vapor barrier. Plastic on the outer surface of a wall in cold weather could cause problems.

The standard installation of a plastic vapor barrier is between the studs and the drywall but there are some exceptions to this. 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. 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. 1 on the interior wall between the heated and unheated portion of the basement i would not use with a vapor barrier.

The main concerns are condensation and drying potential. Polyurethane sheeting is a typical vapor barrier that contractors use to prevent moisture from penetrating the walls of a basement. 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 and.