New Siding Vapor Barrier

To know if you need a vapor retarder ask yourself a few basic questions.

New siding vapor barrier.

Unlike asphalt felt or housewrap liquid applied barriers are rolled or sprayed on to form a continuous seam free coating that is waterproof but vapor permeable. In addition to vapor permeability barricade building wrap provides water and air resistance uv resistance tear strength and temperature resistance. 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. Housewraps and vapor barriers are usually addressed in local building codes in fact many places require some kind of weather resistant barrier so a professional contractor can also make sure that your home is up to code.

Preventing the inward flow of moisture through steel siding while still allowing the outward transfer of moisture trapped in a wall system requires a permeable wrb like barricade building wrap. Start your siding project housewrap and your siding. The process also helps form an effective air barrier. A vapor retarder is a material used to prevent water vapor from diffusing into the wall ceiling or floor during the cold winter.

Canadian codes sources. The science of moisture movement. This article includes photographs of leaks on and perhaps into a vinyl sided house wall. The page top photograph shows that a lot of water more than you might guess may be running over the surface of.

The process is a little more involved than buying a roll of housewrap at the lumberyard and stapling it in place over the sheathing.