Moldy roof

out of sight, out of mind.

I would not use a pressure washer. (yes, I know some do...)
Can you see the roof from below? If not then just leave it alone.
Doesn't hurt it at all to be dirty.

My coach is parked in my driveway under trees for 3/4 of the year...and in the humidity of NC, the roof gets anywhere from black to green. The only way I've found to adequately clean it is to spend a day on the roof with a bucket of Mr. Clean Magic Erasers and lots of elbow grease. I would NEVER consider using a pressure washer as it may penetrate joint seals and cause future leaks. I did find a Mr. Clean Magic Eraser mop that allowed me to stand up when scrubbing and it did a pretty good job. But there's nothing that get it as clean as good ole hands and knees scrubbing. The erasers make the scrubbing a little less intense than just using soap and a rag, but I won't lie to ya....it's still a job!

Beer. The more you drink, the less you care about the dirty roof. :)

Pure bleach and let it soak is about the only thing I've found to get it semi-clean.

I've had class A coach's 12+ years & it has never been this bad.
I've used Tile X, & a brush.......that used to work.
I'll try bleach......I've mixed that 50/50 with water to clean the house roof.
Thanks for the response.

Probably the trees.

Just lightly spray the roof with spic and span or other soap and bleach mix. It really doesn’t need to be all that toxic to kill the mold. Use a yard sprayer. Use plenty of water to rinse which should dilute the runoff so damaging the lawn should be a nonissue.

I spray my cedar siding on my S&B (or more correctly S&CS) with a garden sprayer and bleach 50% and water.
bumpy

Bumpy......that's what I wanna try.
Do you hose it down with plain water after?
Does it kill the vegetation?