I have a concrete tile roof, and had another few companies scared to go on it, or even to use harnesses for safety. PowWow power washing came, did the job with 4000 psi machines, which went way faster than the last company that did this 4 years ago. They were in an out in much less time, used safety harnesses, cleaned up well, and although they weren't as communicative as I would have thought reasonable, they did the job and they did it very well! I had a roofer friend check the roof before they left, and he said even the hidden gutters and valleys were all done very impressively! The price also was exceptional! thanks and way to go Powwow.