Vapor Barrier Seam Tape 3mil is designed to permanently seal seams and hang vapor barrier materials in building and home construction. Vapor barriers are thin wrapped membranes that block moisture transfer between permeable building materials of exterior walls. This quality tape assures durable lasting seams. By blocking moisture vapor passing through walls wood, metal, and masonry, construction is protected from rot. As the vapor moves through unprotected walls, it can condensate and be absorbed by the construction materials. Working at the micro level, damage occures over many years, but the damage is permanent and lessens the life of the building. This quality 4? x 1296? tape?s adhesive is formulated to pull off the roll easily, avoiding binding and stretching while being applied. This vapor barrier seam tape, when installed correctly, seals permanently assuring no vapor infiltration and surpasses code requirements.