How much granule loss is too much for shingles?

How much granule loss is too much for shingles is judged by visible exposure of asphalt and functional loss of UV protection rather than an exact weight measurement. Some granule loss is normal, especially initial shedding in the first year and gradual loss after 15 years, with small amounts in gutters being acceptable. Granule loss becomes too much when you observe bald, shiny black areas on shingles where the underlying asphalt mat is exposed, as this indicates the protective barrier against ultraviolet radiation is gone and rapid deterioration will follow. If gutters and downspouts are consistently filled with large quantities of granules after every rain, or piles of granules accumulate at the base of downspouts, that is excessive. Other signs include shingles that look patchy, faded, or have inconsistent color, or feel smooth rather than gritty to the touch. When more than 30 to 40 percent of granules are missing across large areas, or any single area has complete baldness larger than a quarter, the shingle's ability to protect against UV and provide fire resistance is compromised. At that point, the roof is near end of life and replacement should be planned within 1 to 2 years, as leaks and cracking will soon follow. An inspection can determine if loss is due to normal aging, hail impact, or manufacturing defect.