Need just a little more information? Check out these informative videos on lichen and moss ...
Lichens Scientist's estimate about 6% of the earth is covered with lichens - it is an amazing and resilient bio-organism. Lichens have a symbiotic relationship with algae and is more destructive than algae because it grows deep root tentacles (anchors) that latch on to it's host. Eventually this results in lifting and detaching the protective shingle granules. When you see black streaks on your roof it does not always indicate the presence of lichen. Algae is a warning sign to take action before the serious and costly damage from lichen begins.
Blue-green algae, a.k.a. Gloeocapsa Magma, is a natural air-born spore that is part of our ecosystem. It thrives on surfaces where food, light and water are prevalent, especially on the north and east exposures. Black streaks on roofing and other exterior features are a symptom of an active algae colony infestation.
Moss Prevalent in the woods on the north side of trees and rocks, this aggressive grower is a nuisance to cedar roofing and proliferates on shingle roofing where blue-green algae is host. The spongy moss flourishes in shaded, dark, moist areas. The more moss grows, the more moisture it traps beneath it. Roofing cannot produce lengthy functional performance where moisture is a constant. Like a wet blanket on your roof, trapped moisture degrades the shingle, tar paper and ultimately delaminates decking material (plywood), leading to leaks.
Moss = Moisture = Rot = Damage
"What's Smothering Your Roof?"
Black roof stains are surprisingly not dirt, jet exhaust, pollution or tree sap. The scientific term to describe them isGloeocapsa Magma"GM" or blue-green algae. Black streaks on roofing are a new phenomenon caused by changes in our climate, and in the case of asphalt shingles the introduction of limestone filler incorporated into the material. Roof algae is a naturally occurring cyanobacteriathat survives temperature changes and damaging UV rays by generating it's own protective outer sheath of deeply pigmented dead cells which cause excess heat and moisture to be retained. Infestation's of algae, lichens and moss result in impaired shingle performance with reduced reflective abilities. These conditions ultimately contribute to early decomposition of the shingles, premature roof replacement, higher energy costs and possible hazards to health.