How much granule loss is too much?

How much granule loss is too much is determined by visible signs of exposed asphalt and functional loss of protection rather than a specific measured quantity. Some granule loss is normal, especially in the first year after installation and gradually after 15 years, with a small amount in gutters being acceptable. Granule loss becomes too much when you see bald, shiny black spots on shingles where the asphalt mat is clearly exposed, as this means UV protection is lost and asphalt will deteriorate rapidly. If gutters and downspouts are filled with large amounts of granules after each rain, or if you see piles of granules at the base of downspouts, that indicates excessive loss. Another indicator is when shingles look patchy, discolored, or have inconsistent color due to missing granules, or when the shingle surface feels smooth rather than gritty. If you can see fiberglass mat fibers or the shingle cracks easily due to UV degradation, granule loss has gone too far. As a general rule, if more than 30 to 40 percent of granules are missing across large areas of the roof, or if any single area shows complete baldness larger than a quarter, the roof's ability to shed water and resist UV is compromised and replacement should be planned within 1 to 2 years. An inspection can determine if loss is due to normal aging, hail damage, or defective shingles, which may be warrantable.