Why are my shingles curling?

Your shingles are curling primarily due to natural aging and thermal effects that cause asphalt to shrink and distort over time. Asphalt shingles contain volatile oils that keep them flexible. After 15 to 25 years of exposure to sun, UV radiation, and daily heating and cooling cycles, these oils evaporate, leaving shingles brittle, shrunken, and prone to curling. There are two types, cupping where edges curl upward and clawing where the middle rises, both indicating end-of-life. A major accelerator is inadequate attic ventilation. Without proper soffit and ridge ventilation, attic temperatures can reach 150 degrees or more in summer, essentially cooking shingles from below and doubling their aging rate. Moisture issues also contribute, as water vapor from inside the home can get into the shingle mat if ventilation is poor, causing expansion and curling. Installation factors such as installing shingles over a wet deck, using too few nails, or installing in very cold weather can predispose shingles to early curling. Low-quality shingles with less asphalt content curl faster than premium heavier shingles. If curling is limited to one slope facing south or west, sun exposure is the main driver. If widespread, it means the roof system has reached the end of its useful life and needs replacement, with ventilation corrections included in the new installation to prevent premature recurrence.