On Sunday, July 6, 2014 2:49:56 PM UTC-4, Jeff Liebermann wrote:
On Sun, 06 Jul 2014 07:52:48 -0400, wrote:



I have some moss or algae (not mold) growing on the roof and in a dark

outside corner. I control it by spraying the area with dilute bleach

twice per year:



You might want to string some copper wire across the roof. They also

make copper and zinc strips for the purpose.



Zinc doesn't work at all. Cooper only works for about 2-3 ft

downhill.

"Copper / Zinc Strips Failure - Roof Life of Oregon"

https://www.youtube.com/watch?v=0cb-uZW9tJg


In the video, he says it's copper, but it sure looks like zinc to me.
No copper color that I see. And I can show you roofs here where it's
obvious zinc works, just like whatever it is in that video. You can see
it with zinc flashing on pipes coming out of roofs. For about 4 ft below
there is no moss/algae. But I agree it's far from an ideal solution, you'd
have to put strips every 4 ft.