Re: Roof Mold
Out here in wet Washington I use 'Moss-B-Ware"..green tube..Home Depot/Lowes
Ditto to Scatty. Costco often has it in season as well and it is a lot better priced. It is a granule that you sprinkle at the peak of the roof sections that grow the moss. I've used it now for 17 years and there is not a speck of moss on my roof. When I first saw it, 17 years ago, I got up and killed it with a liquid moss killer (it was summertime) After that I applied the granuals every fall, just as it started to get wet out.
You want the granules to dissolve and slowly run down the roof so don't apply it before a windstorm or a heavy rain.
I will say this. The stuff is hard on steel gutters. I had to have mine replaced last year. (20 years old, 17 of them using the moss killer) The two sides of the house that I have had to apply the moss killer, the gutters were eaten out. I had to hold them together for their last rainy season, with duct tape.
However, the gutters cost 900$ to replace, the roof would cost me 15-20K. Neighbors all around me (same age) are having to have their roofs replaced. Mine is still in excellent shape. Moss will kill composition shingles.