Shingle Algae and Moss

[Doug Keifer]

Would like to get some inspectors opinion on roof stains and moss, Does roof algae ( Black streaks effect the life of the roof. Does Moss on a roof hurt the roof? Thanks for your opinions.

[Rick Cantrell]

Would like to get some inspectors opinion on roof stains and moss, Does roof algae ( Black streaks effect the life of the roof. Does Moss on a roof hurt the roof? Thanks for your opinions.

Opinions vary, some say yes, some say no. I think not.
Within 10 years or so, almost all roofs have it, but a dark roof does not show up as much.

[wayne soper]

the black stains do little, but moss and lichen growth can affect. Lichen can deteriorate the granular surface and moss can create in affect exactly what an ice dam does by allowing water to build up under the shingle.
All can be cured with different types of chemicals. No power washing!!!

[Rick Cantrell]

Thanks for expanding on that Wayne.
My tunnel vision comment focused only on the black stain portion of the OP.

[Raymond Wand]

A species of algae known as Gloeocapsa - natural pigments produced by the algae cells result in the dark discoloration, usually visible after the roofs are about five to ten years old.

Moss will rot out the felt back and cellulose fibres of the shingles.

[Eric Barker]

No power washing!!!

I don't like hearing that. One of the joys in life is blasting things into oblivion. :D