Q: Why are there granules in my gutter? A: Granule loss is a normal process in the weathering and aging of any asphalt shingle. Common causes of additional granule loss: Traffic on roof Shingles applied on very slight slopes (2� in 12� or less), are prone to increased levels of granule loss due to the poor drainage capabilities of the roof. A certain amount of granule loss is to be expected. Shingles are made with an excess of granules on the surface called �hitchhikers�.If the underlying asphalt is prematurely exposed, the appearance and service life of the shingle may be affected.