Moisture Barrier Inside Walls

A vapor barrier s job is to keep water vapor in humid air from diffusing through one side of a wall and finding a cool surface inside the wall.

Moisture barrier inside walls.

Vapor barriers go on the warm side of the wall generally between the framing and the interior sheathing or wall finish and should have a permeability rating of 0 25 or less. Cover exposed foundation walls with 1 1 2 in. A smart vapor retarder is a vapor retarder material with the unique ability to react to changes in relative humidity by altering its physical structure. It combines a primer and finish in a single fast drying coat and is specially formulated for manufactured housing facilities.

Vapor barriers are applied to the interior walls in climates which are predominantly cold while they are best applied to exterior wells in predominantly hot climates. We used thermax brand available through lumberyards of polyethylene vapor barrier because it doesn t require an additional fire barrier. The goal of vapor barrier strategies is to prevent moisture from collecting and corrupting building materials. This material adapts to let moisture out of the wall whether the humidity levels are higher on the outside of the wall winter or the inside summer.

When a vapor barrier is on the side of a wall where the dry air is i e outside in winter or inside in summer moisture problems can occur. Vapor barriers are sheets of plastic or other material placed on one side of insulation sheets. Moisture vapor barrier primer finish interior latex is a coating designed to reduce the loss of moisture through walls and ceilings. 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.

The vapor barrier in this assembly is the precast concrete itself. Plastic specifically 6 mil polyethylene plastic is. Finished basements often receive a vapor barrier layer between the concrete and the floor treatment to prevent damage from heavy rains or other moisture seepage. Therefore this wall assembly has all of the thermal insulation installed to the interior of the vapor barrier.

Without a vapor barrier in place condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria. Additionally consider installing vapor barriers should you be building new or willing to weather renovation. Of particular concern is the fact that the thermal insulation is air permeable except where spray foam is used. Improperly installed a vapor barrier may actually trap moisture inside a wall while a wall that is more porous can breathe effectively and be less susceptible to long term moisture problems.

This not only insulates the walls but also keeps rising dampness in the concrete from getting into the crawlspace.