Blue Green Algae On Roof Shingles

If you ve noticed it on your roof you may have mistaken this common algae for mold or mildew.

Blue green algae on roof shingles.

Typically it will appear as dark black stains or streaks. The black stains you see on your roof aren t the algae itself but a hard dark coating it creates to protect itself from the sun s harmful ultraviolet rays. Blue green algae usually brings images of lakes and waterways clogged with algae causing damage to the ecosystem not a roof. A roof may develop different types of algae lichens and fungi as bacteria take over.

If a new roof is in order then suggest gaf shingles with stainguard protection to help ensure the beauty of a roof against unsightly blue green algae. The black mold like stains and streaks that appear on roofs particularly light colored asphalt shingles is actually a blue green algae gloeocapsa magma. While it doesn t cause substantial damage to the roofing surface the black streaks can certainly make it ugly. Algae can grow in moist shaded areas so if a homeowner has trees hanging over their roof tell them to trim them back to let the sunshine warm and dry the roof.

However algae is commonly found on roofs across the usa and canada. According to algae expert michael guiry algae base at references some of these black algae are as identified in the lab blue green or even lichenized algae while others are a diverse group of coccoid algae like our microscope photo of more green algae from a roof sample below that are turning out be be very diverse. A blue green algae known as gloeocapsa magma could be the reason you have the algae which is spread by airborne spores sometimes it can also be caused by an accumulation of mildew mold dirt or defective shingles. Commonly found in climates with warm humid summers it does no damage to the roofing but it certainly does looks bad.

In addition to moisture from rainwater blue green algae also eats the limestone filler that s used to make the asphalt shingle granules. Many homeowners mistake algae for roof mold in most cases however it is really a blue green type of algae and when it dies it leaves dark streaks on your roof. Living in a humid area of the country like florida you ve probably seen your asphalt shingle roofs with unsightly dark streaks on them. Algae can cause unsightly stains and growths on your new roof.