Höyrynsulkuja

Höyrynsulkuja, which translates to vapor barrier in English, is a material or membrane used in building construction to prevent moisture from entering wall cavities and other building structures. Its primary function is to control the movement of water vapor, which can be generated by sources like cooking, showering, and breathing within a building. If this vapor condenses within the building's insulation or structural components, it can lead to a range of problems, including mold growth, rot, and reduced thermal performance.

Vapor barriers are typically installed on the warm side of the insulation in cold climates, meaning they are placed on the interior side of the wall assembly. This placement helps to prevent warm, moist indoor air from reaching the colder exterior surfaces where condensation would occur. In warmer, humid climates, the placement might be reversed or a vapor retarder might be used instead, as the direction of vapor drive can change.

Common materials used for vapor barriers include polyethylene sheeting, aluminum foil, and specially coated papers or membranes. The effectiveness of a vapor barrier is measured by its permeance, which indicates how easily water vapor can pass through it. Materials with very low permeance are considered effective vapor barriers. Proper installation is crucial, as any gaps or tears in the material can compromise its function. This includes sealing all seams and penetrations meticulously.