The Roof Cleaning Institute Of America Training & Certification Forum
"Find A Certified Roof Cleaner Directory"

A HO asking for insurance is one thing but asking twice is another.  It would make me a little leary especially if he stressed it.  Even more if he had tarps on his roof.  And why is he having his roof cleaned before repairing it??? 

I think I would pass on it, or any roof that had tarps on it.  I would tell him to use his money to repair his roof first.  Then call me after it has been fixed and I would be happy to clean it.

However if you do decide to clean it you should be able to use a weak solution.  I would say 10 to 20% SH and a little extra surfactant.  And then rinse real good.  You don't need to use a whole lot more surfactant, it will just make it harder to rinse. 

Jon