Besides offering a surplus of good looks, most asphalt architectural shingle products have a design feature that helps prevent a common aesthetic problem: black streaks caused by algae. This is commonly seen on roofing shingles in areas with high humidity and rainfall totals. Algae-resistant shingles are coated with copper or zinc granules, which leach over time, inhibiting algae growth. Because of their greater thickness, architectural shingles have better wind tear-off resistance. Some are rated at 120 miles per hour. They are also highly fire resistant especially if they have a heavy granulated top coat. A heavy layer of top coat granules provides the highest fire rating of Class A.