What is algae discoloration?

• A. A type of roof discoloration caused by algae.
• B. A decorative pattern.
• C. A fungus unrelated to algae.
• D. A type of metal corrosion.

Answer: (A)

Algae discoloration is staining on roof shingles caused by algae growth. This is the best choice because the term describes a type of roof discoloration produced specifically by algae, not by decorative design, fungus unrelated to algae, or metal corrosion. The discoloration typically appears as green, black, or brown patches or streaks on the shingle surface, usually where moisture and shade promote growth. It’s mainly cosmetic, signaling moisture retention and potential aging of the roof, and it can be managed with moisture control and preventive measures like zinc or copper strip systems or appropriate algaecides, while avoiding harsh cleaning methods that could damage shingles.