Kosteussulkeet

Kosteussulkeet, often translated as moisture barriers or vapor barriers, are materials used in construction to prevent or control the passage of moisture through building assemblies. Their primary function is to limit the movement of water vapor from warmer, more humid interior spaces to colder, drier exterior areas, especially during colder months. This is crucial for preventing condensation within walls, floors, and roofs.

When water vapor encounters a surface below its dew point temperature, it can condense into liquid water. This condensation can lead to a range of problems, including mold growth, rot, and reduced insulation effectiveness. Kosteussulkeet are typically placed on the warm side of the insulation in a building envelope. The specific placement and type of material depend on the climate and the overall construction design.

Common materials used as kosteussulkeet include polyethylene sheeting, kraft paper facings on insulation, and certain types of paints or coatings. The permeability of a kosteussulkeet is a key characteristic, often measured in perms. Low-permeance materials are generally considered more effective as vapor barriers. The proper installation of kosteussulkeet is as important as the material itself, as any gaps or tears can compromise their effectiveness. In some climates, particularly those with high humidity or where buildings are cooled significantly, a "vapor retarder" might be used instead, allowing for some vapor diffusion rather than a complete blockage.