Algae streaks

In NC's humid climate, most asphalt shingle roofs develop some algae staining by year eight to twelve. The streaks appear first on north-facing slopes (less sun, slower drying) and work around the roof. They look alarming but on their own they do not indicate structural damage. A roof can streak heavily and still have years of serviceable life in the mat. The issue arises when algae staining is conflated with storm damage — they are separate conditions and should be documented separately.

Algae-resistant shingles — those with copper-granule infill, marketed as "AR" or with "StainGuard" designations — are available from all three major manufacturers and are worth the upgrade on any replacement in NC's climate. They carry enhanced algae warranties and typically defer visible re-streaking by several years compared to standard shingles. The cost difference is modest per square. On a storm-claim replacement, requesting the AR version of the like-kind shingle is a reasonable specification that most carriers will accept.