On Sat, 03 Nov 2012 17:39:46 -0400, Bob wrote:

Hello,

Have noticed a fair amount of greenish Mold (or Moss ?) on shingles in
some areas of my roof.

Live in New England; gets quite cold up here during the winter.

- Is it harmful for the Shingles ?
(my primary question and concern)

- Will the cold temp. kill the stuff over the winter ?

- Will it rejuvenate itself in the Spring ?
Or, just new patches in other areas likely ?

What causes ?

If it is really necessary to treat before the winter sets in, and I can
get up there to spray it with something, what's good to use that
won't harm the Shingles ?

Would prefer, I think, a commercial product rather than mixing something
up myself.

Thanks,
Bob

Once you begin to see that green stuff on your roof, that's an indicator
it's time for a new roof. Replace it before winter or you will have
leaks.