Specially formulated to remove tough dirt, pollen, mildew and fungus from roof membranes and existing waterproof systems. The first step in every Silicone Roof Coating System. Ssafe to use on aged asphalt, aged EPDM and TPO/CPA, built-up, cap sheet, composite, concrete, fiberglass, metal, modified bitumen, tar and gravel, torchdown, most existing coatings and coated polyurethane foam. When mixed at a 9:1 ratio, 1 gallon will clean up to 4,000 sq. ft.