Roofing Glossary

Lichen on Roofs

Lichen — those pale green, gray, or orange crusty circles on aging shingles — is a symbiotic organism (fungus plus algae) that anchors itself directly into the shingle's granule layer. It is tougher and more firmly attached than moss or algae.

Lichen spreads slowly in circular patches, bonding to the granules with remarkable tenacity. Scrubbing it off mechanically usually takes granules with it, so the correct approach is chemical treatment followed by patience: kill it, let weather loosen it over weeks, then gently rinse.

Like moss, lichen indicates persistent surface moisture and shade. It is primarily a cosmetic and granule-wear issue rather than a leak risk, but heavy colonization accelerates the roof's cosmetic decline.

Why It Matters

Aggressive removal does more harm than the lichen itself. If lichen bothers you, treat it chemically and let time do the work — or accept it as patina on an older roof.

Questions about your own roof? Request a free estimate or call Nucci Brothers Roofing at (301) 458-1003.