Shingles are designed so that the granules block the UV of the sun and protect the asphalt underlayment. As the shingles age the granules fall off over time. As the asphalt is exposed the UV, it dries out and the shingle gets a "potato chip" appearance as the corners start to curl up. A shingle at the extreme end of its life is bubbled in appearance and is brittle to the touch. A 20-year shingle is warranted by the manufacturer to have a useful life, under optimal ventilation conditions, of 20 years.
Hail does several things:
- Accelerates granule loss
- Accelerates shingle aging.
- Voids manufacturer's warrantees
- Leads to other associated problems