How To Install Vapor Barrier On Concrete Walls

Cover exposed foundation walls with 1 1 2 in.

How to install vapor barrier on concrete walls. A vapor barrier is not the same as an underlayment. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Vapor barriers are a way to keep moisture from getting into the concrete. The science of moisture movement.

With fiber insulation and a vapor barrier moisture can get trapped in the insulation leading to moldy insulation and decay in the wood framing. Of rigid moisture proof insulation. Finish the wall within a month of installing the barrier to prevent damage to the surface and protect the vapor barrier. To be extra certain use a caulk gun to place caulk material around the tape to double seal the barrier.

Before attaching the vapor barrier to the wall it is essential that you wash the concrete to remove substances such as mold grease or sand. In this video you ll learn how to install a proper poly moisture vapor barrier against your block basement wall before finishing and closing up your wall sec. Find out where to buy vapor barriers and other problem solving products. To clean the wall mix up a dilution of water and trisodium phosphate or tsp in a bucket.

If you have a concrete floor that s in continuous contact with a source of moisture you re going to have problems. 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. To be effective a vapor barrier must be installed in a way that prevents any water vapor from getting to the slab. We used thermax brand available through lumberyards of polyethylene vapor barrier because it doesn t require an additional fire barrier.

The water vapor can come through the concrete from the soil or from indoor air that comes in contact with the concrete. The problem is that moisture tends to condense on the cool concrete walls. Using other kinds of tape will compromise the waterproof seal and render the barrier useless. This is why a vapor barrier under concrete is essential.

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. Follow the instructions on the tsp when measuring ratios of water to tsp. In any case the vapor barrier must point to the warm side. Also be sure to use treated lumber for the bottom plate on the wall framing.

Thus installing vapor barriers on wall surfaces must.