Aurutõkkematerjalid

Aurutõkkematerjalid, also known as vapor barriers or vapor retarders, are materials used in construction to prevent or slow the diffusion of water vapor through building envelopes. Their primary function is to control moisture within walls, roofs, and floors, thereby preventing condensation, mold growth, and structural damage. In colder climates, vapor barriers are typically installed on the warm side of the insulation, preventing interior moisture from reaching the cold exterior sheathing and condensing. In warmer, humid climates, the placement might be reversed or a vapor-permeable material may be used on the exterior to allow trapped moisture to escape.

Common materials used as vapor barriers include polyethylene sheeting, asphalt-coated kraft paper, and certain types of paints and membranes. The effectiveness of a vapor barrier is measured by its permeance, which indicates how easily water vapor can pass through it. Materials are classified based on their permeance ratings: Class I (impermeable), Class II (semi-impermeable), and Class III (vapor-permeable). The choice of material and its placement depends on the climate zone, the type of construction, and the intended use of the building. Proper installation is crucial, as any gaps or tears in the vapor barrier can compromise its effectiveness.