The Daring Dufas wrote in
:

Red Green wrote:
"benick" wrote in
:

wrote in message
...
I had new roofing installed (GAF 50 year asphalt shingles) about 5
years ago. I've noticed that over the past year its started to
develop growing moss and algae on certain sections which are
located under tall oak trees. The old roof, under the same trees
for 30 years had NONE of this growth. I've also noticed that on
one side of my house, the same end of the house with the roof moss,
has algae growing relatively significantly on my white alum siding.
Again, only the past year or so.

This side is south facing and there are no side trees blocking
horizontal sun exposure.

So, my questions a

What might be causing this condition starting only this past year?

What damage is being caused by the moss on the shingles?

What could I do to eliminate and prevent future growth?

Any possible recourse with the shingle manufacturer?

Thanks for any/all advice provided.

B

Very first result from Bing
search....http://www.askthebuilder.com/539-Rem...s-and-Algae-Fr
om -Roofs.shtml

Brush it off with a stiff bristle brush and add copper strips under
the cap with an inch or 2 of copper exposed....



Zinc strips are often used. Lot less expensive. Have no knowledge of
comparison of effectiveness.

I thought copper worked too?

TDD


Yep, that's my understanding as well. I believe they use zinc and copper
in shingles during manufacture. These are usually called AR (algae
resistant) Shingles. Note "Resistant" which is totally subjective and
arguable. I do not know if there is a independent spec to be classified
as AR.