Keeping the Rain Where It Belongs: An Homage to Roofs

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Why Your Asphalt Shingles Are Losing Granules

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The mineral granules on asphalt shingles protect the shingles from physical and weather damage. Anything that dislodges the granules exposes the shingles to accelerated wear. Below are some of the things that can strip granules off shingles.


Weather-related damage is a common cause of granule loss. A hailstorm, for example, can strip granules over a large surface area of your roof in a single day. The concentration, velocity, density, and size of the hailstones determine their damage. The duration of a hailstorm also determines the extent of the granule loss. The loss will be greater on aging roofs than newer roofs.

Foot Traffic

Foot traffic causes granule loss due to the friction between the feet and the roof surface. The loss is gradual — the shingles will lose some granules each time someone goes up the roof. Dropping things, such as hammers or other materials on the roof will also contribute to the granule loss.

Weathering due to foot traffic affects specific areas of the roof — the areas that experience foot traffic frequently. This form of weathering occurs gradually.


Granule loss is part of the natural aging process of asphalt shingles.  The granules protect the shingles from weather damage, but they are also susceptible to weather elements. Exposure to various forms of precipitation and sunlight are the major agents of weathering. Aging-related granule loss occurs gradually and affects the roof as a whole.

Manufacturing Defects

Some shingles lose their granules due to manufacturing defects. The defects can affect a single box of shingles or a whole batch of shingles. A common defect is where the manufacturer failed to formulate or mix the individual shingle materials properly. Such defective shingles suffer gradual granule loss, but the loss is accelerated compared to aging-related granule loss. You might notice manufacturing defects on specific areas of the roof, but not others.

Improper Storage

Your roof can also lose granules due to poor storage before installation. Shingles survive best in dry environments. You should also keep the shingles on flat surfaces, preferably in their original boxes. Exposing the shingles to moisture or high temperatures accelerates wear and tear. Such shingles will lose their granules even after installation. This form of granule loss may only appear on specific sections of the roof — the sections with the improperly stored shingles.

Know why your shingles are losing granules. Deal with the cause if it's something you can stop. Otherwise, replace the affected shingles if the damage becomes too much.

To learn more about roof installation, repair, and maintenance, contact a local roofing company such as JC Roofing & Insulating