What are the signs that shingles need replacing?

Several clear signs indicate that shingles need replacing rather than simple repair. The most obvious is widespread curling, cupping, or clawing where shingle edges turn up or centers lift, indicating loss of waterproofing ability. Extensive granule loss is another major sign, visible as bald spots on shingles, heavy granule accumulation in gutters and downspouts, and the underlying asphalt mat showing through. Cracked or broken shingles across large areas, especially after wind events, indicate brittle, aged mats. Missing shingles that keep occurring after wind storms suggest seal failure. Daylight visible through the roof boards in the attic, or water stains and leaks on ceilings and in the attic, indicate failure. Moss or algae growth that is extensive can trap moisture and accelerate deterioration, though some algae is cosmetic. A roof that is 20 to 25 years old for architectural shingles is near end of life even without visible issues. Other signs include sagging deck areas, shingle granules clogging downspouts, neighbors replacing their roofs of similar age, and higher energy bills due to poor ventilation. If you see three or more of these signs across the roof, have a professional inspection. Isolated damage can be repaired, but widespread symptoms mean replacement is more cost-effective than continual repairs.