Niiskustõkked

Niiskustõkked, also known as vapor barriers or moisture barriers, are materials used in construction to prevent moisture from migrating through building elements. Their primary purpose is to control the movement of water vapor, which can occur through diffusion or air leakage. By reducing or eliminating this moisture transfer, niiskustõkked help to prevent a range of problems, including condensation within walls and roofs, which can lead to mold growth, material degradation, and reduced insulation effectiveness.

The effectiveness of a niiskustõkked is determined by its permeance, which measures how easily water vapor can pass through it. Materials with very low permeance are considered vapor barriers, while those with slightly higher permeance are called vapor retarders. The choice between a barrier and a retarder depends on the climate and the specific building assembly. In colder climates, niiskustõkked are typically installed on the warm side of the insulation to prevent interior moisture vapor from reaching cold surfaces and condensing. In warmer, humid climates, the placement might be on the exterior or not used at all, depending on the wall construction.

Common materials used as niiskustõkked include polyethylene sheeting, aluminum foil, and specialized membranes. Proper installation is crucial for their performance. This involves sealing all seams and penetrations carefully to ensure an airtight and continuous barrier. Inadequate sealing can significantly compromise the intended function of the niiskustõkked, allowing moisture to bypass the barrier and cause damage. The use of niiskustõkked is an important aspect of creating durable, healthy, and energy-efficient buildings by managing moisture effectively.