Products / GAF Master Flow Zinc Moss & Mildew Preventer

Master Flow Zinc Moss & Mildew Preventer (NMM50) is a zinc strip installed along both sides of the roof ridge with most of the strip left exposed; when it rains the exposed zinc oxidizes and leaches zinc oxide that helps inhibit moss and mildew growth. GAF says it does not kill moss or mildew, calls it EPA-approved, and lists it for asphalt shingle, wood shake and tile roofs.