How To Install Vapor Barrier On Concrete Walls

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.

How to install vapor barrier on concrete walls.

If you have a concrete floor that s in continuous contact with a source of moisture you re going to have problems. The water vapor can come through the concrete from the soil or from indoor air that comes in contact with the concrete. Also be sure to use treated lumber for the bottom plate on the wall framing. This not only insulates the walls but also keeps rising dampness in the concrete from getting into the crawlspace.

A vapor barrier is not the same as an underlayment. Of rigid moisture proof insulation. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Cover exposed foundation walls with 1 1 2 in.

To clean the wall mix up a dilution of water and trisodium phosphate or tsp in a bucket. 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. Thus installing vapor barriers on wall surfaces must. The problem is that moisture tends to condense on the cool concrete walls.

Vapor barriers are a way to keep moisture from getting into the concrete. We used thermax brand available through lumberyards of polyethylene vapor barrier because it doesn t require an additional fire barrier. Find out where to buy vapor barriers and other problem solving products. 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.

Astm e 1643 standard practice for installation of vapor retarders used in contact with earth or granular fill under concrete slabs provides details but here are a few tips. To be effective a vapor barrier must be installed in a way that prevents any water vapor from getting to the slab. To be extra certain use a caulk gun to place caulk material around the tape to double seal the barrier. This is why a vapor barrier under concrete is essential.

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. Finish the wall within a month of installing the barrier to prevent damage to the surface and protect the vapor barrier. In any case the vapor barrier must point to the warm side. Using other kinds of tape will compromise the waterproof seal and render the barrier useless.

The science of moisture movement.