I think I purchased all the books that were out there on powerwashing businesses when I first started out 4 years ago. Don't waste your money. They all are basic books or info that most of us already know. Your best bet is to look in this site to answer your questions. Lots of info in here. Also nothing is better than practice. Believe me these books are not worth it.
I have to agree with Rick. I have yet to read one with enough advanced information to get you anywhere. I've been writing a book for the past three years (actually more like compiling information and writing articles) that is going to include everything one would need to hit the ground running with a PW'ing business. If I could split off into twins I might actually be able to get the thing finished and published.
Hey Barr, since you may be the only guy that buys it, I may have to change the cover price to $2000 to offset printing costs. But that will include a signature [bb]