It needs heat moisture and nutrients to grow.
Fungal growth on roof shingles.
Scrubbing or power washing the lichen will only do more damage.
Lichen is a photosynthetic fungus that has roots that wrap around the granules feeding on the nutrients of the gm and the filler in the shingles.
It is easily spread and causes those colorful stains on so many roofs.
Most of the stains on the average atlanta roof are the result of algae and not fungus.
Some roof shingle materials contain algaecides or fungicides which will also retard moss growth on the roof surface.
Some moss or fungi development you may see are dark brown or black spots that weaken shakes or shingles.
This unique advance in shingle technology gives long term fungus protection for the entire roof.
They call it the algaeblock system.
Once on the roof lichen cannot easily be removed.
It is important that the product you choose to clean the moss growth does not damage or weaken the cedar itself.
However most of the anti algae products also work in fighting fungal growth.
These kinds of organic growth will degrade cedar roofs much faster than a lot of other roofing issues.
Known as black algae or roof mold gloeocapsa magma is usually blamed on dirt accumulation mold and mildew or defective shingles.
Algae resistant shingles or ar shingles for short began when shingle manufacturers looked for ways to gain market share.
A brief history of algae resistant shingles.
On an asphalt or possibly some treated wood shingle roofs shingle chemistry is also involved in moss lichens and algae growth or resistance to it.