How does hail damage a roof?

The average hailstorm lasts only five minutes, but the hail damage they leave behind totals about $1 billion a year, according to the National Weather Service. When hail hits, it can damage the roof or covering of your home as well as other personal property, which is why it’s important to schedule a professional roof inspection after each storm to assess any damage.

Hail damage on a roof can be seen as indentations and/or fractures on the shingle’s surface. Hailstones vary in size, shape, and hardness and can create a random pattern of dents or depressions. If this is not evident, look for indentations on metal flashings, siding, chimney caps, or even skylight flashings. After some time, clusters of granules may come off (at the point of impact) in a random pattern and expose the asphalt.

The most common types of hail damage include:

• Granule loss. Loss of mineral granules as an immediate or gradual consequence of storm damage can lead to the asphalt coating being directly exposed to the elements. This may lead to accelerated aging of the shingle.
• Cracks in the granule-asphalt surfacing. Cracks may be present especially if high winds blew the shingles back.
• Exposed fiberglass mat. If the hail is large enough, it can shatter the granule-asphalt surfacing causing it to break away from the fiberglass mat.
• Fractured fiberglass mat, which may or may not be immediately visible. A fractured mat may result in tears radiating out from the points of impact. Furthermore, hidden damage to the mat may later develop into cracks and tears in time as the shingles age.
• Loosening of the self-seal strip. This damage may or may not be immediately visible and may weaken the seal integrity, creating the possibility of future shingle blow-off.