Asphalt, an oil based product, is resistant to water and used in a wide range of waterproofing areas. Shingles are primarily asphalt in construction. Asphalt does dry-out over time. This process is called oil migration. As with most natural elements, when asphalt dries it shrinks. The shingle’s fiberglass intermat tries to prevent the shrinkage. This event is visible on this Immokalee roof. We typically find shingle’s corners curling. Improper ventilation accelerates the curling process. If shingle curling is occurring on your roof, roof replacement is near.