The grit on shingles is actually ceramic-coated mineral granules that are intentionally embedded into the asphalt during manufacturing and serve several critical protective functions, not just decoration. These granules are typically made from crushed rock coated with ceramic and pigments to create color. Their primary purpose is to protect the underlying asphalt and fiberglass mat from ultraviolet radiation from the sun. Asphalt degrades rapidly when exposed to UV, so granules act like sunscreen, blocking UV and significantly extending shingle life. Second, granules provide fire resistance, helping shingles achieve a Class A fire rating. Third, they provide color and aesthetic appeal, with various blends creating dimensional looks. Fourth, they add weight and physical protection against hail impact, foot traffic, and weathering. Fifth, some granules are coated with copper to provide algae resistance, such as Atlas Scotchgard Protector technology. Over time, it is normal for some granules to loosen and wash into gutters, especially in the first year after installation and as the roof ages past 15 years. However, excessive granule loss exposing black asphalt indicates advanced aging and loss of UV protection, meaning the roof is nearing replacement. Never pressure wash shingles, as it strips this essential grit.
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