How can I fix curling roof shingles?

Fixing curling roof shingles depends on whether curling is minor and isolated or widespread across the roof. For a small number of shingles that are still flexible, you can perform a temporary repair that may last a few years. Wait for a warm day above 60 degrees when shingles are pliable and less likely to crack. Gently lift the curled edge and apply a generous amount of asphalt roofing cement or roofing sealant underneath with a putty knife, spreading it under the curl and onto the shingle below. Press the shingle down firmly and hold for 30 to 60 seconds. Place a heavy flat object like a brick or board on top for 24 hours to keep it flat while cement cures. If needed, add one roofing nail just above the curl line, then cover the nail head with roofing cement to prevent leaks. This works for minor cupping or clawing. However, if shingles are brittle, crack when bent, or curling is widespread, repair is not effective because curling indicates loss of volatile oils due to age, typically 20 plus years, or inadequate attic ventilation causing heat buildup. In that case, the only long-term solution is full replacement, and you must correct ventilation by adding soffit and ridge vents to prevent recurrence on the new roof.