Products / CertainTeed DiamondDeck

DiamondDeck is CertainTeed's scrim-reinforced synthetic polymer underlayment for use beneath asphalt shingles, wood shingles and shakes, metal and slate, sold in 4 ft. x 250 ft. rolls (1,000 sq. ft.), 14 mils thick and 37 lb. per roll, with printed diamond nailing targets and a slip-resistant top surface. The data sheet requires 1 in. plastic cap nails (no staples), limits UV exposure to 180 days, and says it is not ice-dam protection or a waterproofing underlayment. It lists a UL 790/ASTM E108 Class A rating when installed in a system beneath Class A shingles.