Fiberglass reinforcement helps resist wrinkling and bucklinglays flatter under shingles, Special adhesive allows for one-time repositioning, but aggressively adheres over time, Self-seals around nails or metal roofing fasteners, Dual-side selvedge and split-back release film speed installation for greater home val, Can be left exposed for up to 60 days if necessary on asphalt shingle roof systems. Weather Watch® Leak Barriers are excellent vapour retarders exceeding ASTM D1970 requirements with a .05 vapour permeance (based on internal testing), Installed coverage will be less and depend on quantity and width of side and end laps