Your roof is a big investment. Help protect it right from the start against water damage in the attic, which can cause mold growth and rotting deck boards. Deck Defense® High Performance Synthetic Roof Underlayment features a durable construction that works with your shingles to help shield your home from moisture infiltration. Acts as a non-absorbent, secondary water-shedding barrier. Unique bottom surface coating reduces the chance for tears that cause leaks, as compared to other felt underlayment. Provides roof deck protection from UV exposure for up to 6 months*. Extra wide rolls cover approximately 5 times more than standard #30 felt rolls. Preprinted nailing pattern and overlap lines help speed installation.