Hello, We have been offering power washing for old stone and concrete patios for a year now. And we have been doing alright with it. The question is, what is the correct pricing for these services? We work on the state of Maryland, and I know that prices vary greatly. But I wanted to have an idea to make sure that we are not overpricing or underpricing. We tend to charge by the hour since it is easier than measuring bigger surfaces. Thanks!