A word of warning about powdered moss killer you shake out of a can. I did Stonefishe's project on my Mom's roof last summer and when done bought a can of moss killer to shake on the peak of the roof as a future preventative. The brand name slips my mind and the can is long gone but it was tall, round and I believe, purchased at home depot.

It was a warm day with a bit of a breeze. I'm in jeans, tshirt, romeos and ball cap. When I got home I had a reaction from all the moss killer dust that float through the air and landed on me. my face was flushed and red for about 2 weeks and itched a great deal. I figured since I was sweating some, the dust got on the sweat soaked liner of my hat and worked it's way down my face. The whole experience was pretty uncomfortable. The spooky part was as I applied the stuff on the roof, there was no indication that I was getting any on me. It was bad enough I threw away the clothes and hat as I didn't want that $hit getting in my washing machine.

Be careful!