How to fix curled up shingles?

Fixing curled up shingles depends on the cause and severity of the curling. Curling occurs in two forms: cupping where edges turn upward, and clawing where middle rises and edges stay flat. Both indicate aging, moisture issues, or poor ventilation, but you can temporarily repair minor curling. For a few shingles that are only slightly curled, on a warm day when shingles are soft and pliable, you can flatten them. Apply a generous amount of roofing cement or asphalt roof sealant underneath the curled portion with a putty knife, then press the shingle down firmly. Use a brick or heavy weight to hold it flat for 24 hours to allow cement to set. Drive an additional roofing nail near the edge if needed, and cover the nail head with roofing cement to prevent leaks. This is a temporary fix that may last 1 to 2 years. If curling is widespread across the roof, involves many shingles, or shingles are brittle and crack when you try to flatten them, replacement is the only proper solution, as curled shingles have lost their waterproofing ability and will not reseal. Widespread curling usually indicates the roof is at end of life or the attic has inadequate ventilation causing heat buildup, which should be corrected before new shingles are installed. Never try to fix curled shingles in cold weather when they are brittle.