The Tilex definitely made for quick work. Using the built in pump sprayer, I just wet a quarter of the roof at a time, (what I could reach standing on the step ladder with a long handled scrub brush), give it about 5 minutes to soak, then took the stiff brush to loosen things up. Then, a rinse off with the pressure washer wand. What stains that remained would get a second pass. I'm going to relocate the Scamp
to a spot not directly under the Maple Tree, and if I'm not going to be in it all the time I'll get a car cover. But it's still serving as the occasional backyard office/radio shack, so keeping it covered will be rare.