Does the roof on your house look like this?
All that stuff on your roof is a mix of moss, lichen, and fungi. You can look up those three things on your own to figure out more of what they are. But for our purposes here, they’re life. They’re lifeforms growing on your roof.
Are they destroying your roof? No. Or at least not on the time scale that we live. If we lived for 500 years, then yeah, maybe it’d be a problem. But not for our short lives.
So they don’t need to be cleaned off? No. They don’t. They don’t do anything bad to your roof. When it comes to home maintenance, put your money towards something that really needs to be done, not roof cleaning.
The only reason to clean your roof is for looks. Purely cosmetic.
What if I want to clean my roof anyways? Waste of money, dudes, but okay, let’s say you want to for cosmetic reasons.
Most companies will pressure wash your roof. This is VERY BAD, especially if your roof is aging. Pressure washing has the tendency to rip shingles off your roof or create leaks where there were none. Do not do pressure washing, even though it’s always the cheapest option.
There’s also “soft washing” which still uses water pressure, but much less. This is okay to use if your roof is newer.
The safest bet is people who use brushes and no water pressure systems. You won’t lose shingles this way, you won’t create leaks, and they tend to do a better job.
Of course, if your roof doesn’t have a crazy pitch to it, then you can get up there yourself with a scrub brush and do the best job of all.