WeatherMaster® Ice & Water Underlayment is a composite roof underlayment designed to provide a secondary waterproofing barrier needed to prevent ice dams and damage from wind-blown rain. A proprietary fiberglass mat reinforced, SBS-modified asphalt makes WeatherMaster® Ice & Water Underlayment ideally suited for continuous waterproofing protection against ice dams and wind-blown rain year after year. The self-adhesive underlayment creates a watertight barrier by sealing to the roof deck and around nails. WeatherMaster® Ice & Water Underlayment provides excellent traction and protection from UV degradation and weathering thanks to its granular surface.