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