Phew....thanks for that.
Considering the sun, hail, torrential downpours....not to mention ice and snow.
Maybe I should install a roof OVER the roof?
Just make sure you wash that new roof. :B
I've been using pressure washers for longer than I'd like to admit. The trick is to use the correct tip, correct pressure, and keep enough distance from what you're cleaning. The soap that's being used should be doing the heavy lifting, not the pressure. A mid-grade pressure washer actually uses less water than a garden hose.
On a related note: EPDM roofs don't benefit from washing but it may keep streaks off the sidewalls.