Moss on roof

[Slingah]

Use bleach or liquid pool shock(sodium hypochlorite) and T.S.P. or Jomax in a pump up sprayer.
Wet roof FIRST and all surrounding plants, bushes, grass etc. with plain water...then apply mix to roof. Let the chemical do the work. Sometimes a second application is needed.
Don't be afraid of the bleach....it will NOT hurt asphalt shingles and is the ONLY thing that will work.

bleach is 6% sodium hypoclorite
liquid pool shock is about 12% sodium hypoclorite
I buy pool shock at Ocean State Job Lot to do all my exterior cleaning.

[Slingah]

Also in my experience with lichen it is better to not scrape or scrub the lichen off but to just treat the roof with the mix, kill the stuff and let it eventually just die, dry up and fall off. If you scrape it it will pull off the granules on the surface of the shingle.