Today I partially removed a section of roofing to make way for a Portical I am building on 1930s Cottage style house, This is what some parts of the roof looks like.
I had to look at it a second time and noticed it looked like my shed roof after I cleaned it.
I pressure washed mine after I killed the moss and surprised I did not loose much granule. Of course mine was black.
I see the lichen and moss on a lot of roofs, usually under a tree overhanging the roof, or on the north side of the lower roof shaded by the upper floor. I’ve always commented on it being there and that it should be carefully removed. But when they ask me how to do that, I just say “carefully”, maybe with a non-aggressive broom. How best should one clean that lichen off without damaging the roof? I saw a neighbor with a pressure washer do it several years ago, and 3 years later when I moved away I could still see the marks on his roof where he sprayed.
All kind of products out there if you Google it.
I tried it on my shed with a moss killer, waited a week and then used my low pressure washer to clean it off. Did not damage the shingles except where the lichen had already eaten away down to the matt surface. Posted the picture^^^^