Apr 28, 2023 · Apply BITUTHENE 4000 membranes in lengths up to 8 ft (2.5 m). Overlap all sea at least 2.5 in. (65 mm). On walls higher than eight feet, apply membranes in two or more “HDPEngled” lifts, with the upper sheet overlapping the lower by at least 2.5 in. (65 mm). Roll all membranes with a hand roller.