Moisture Barrier Concrete Basement Walls

Fiberglass insulation inside a bag hanging from the rim joist down along the foundation wall.

Moisture barrier concrete basement walls.

Then insulation and then a vapour barrier. This is a water infiltration barrier and perhaps an air barrier designed to cause water to flow down and out not into the wall. According to shannon of house improvements the best moisture barrier is rigid foam that is sealed. Be sure to use adhesive formulated for use with foam about 3 per tube when insulating basement walls.

When the mold grows it will spread to everything around it studs drywall etc. Most paint and hardware stores carry elastomeric oil based or latex paints that seal almost all masonry against moisture. With fiber insulation and a vapor barrier moisture can get trapped in the insulation leading to moldy insulation and decay in the wood framing. But if you use fiberglass insulation batts then a moisture barrier will prevent water and moisture from entering your walls and creating mold and mildew.

The foam greatly reduces heat transfer through the masonry and framing and it eliminates the need for a plastic moisture barrier later. 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 water vapor can come through the concrete from the soil or from indoor air that comes in contact with the concrete. You should then use fiberglass insulation that has a vapor barrier between the studs with the vapor barrier facing in toward the living space.

Of foam against the wall this should not be a problem in your climate. These moisture barrier paints are not guaranteed if the concrete is crumbling or badly cracked but can be applied over repairs or under carpet and paneling to help keep your basement dry. When the soil outside becomes saturated water can seep through these cracks. Actually a concrete wall or a masonry wall without cracks is in itself a very good air barrier.

If you have a double brick wall in the above ground portion of the house we will often find some kind of building paper against the brick inside the house. Stud wall filled with fiberglass insulation an inch or two away from the concrete wall. 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. Plastic vapor barrier against concrete wall fiberglass insulation inside stud wall then drywall.