The difference between the $75 could mean the difference between thousands of dollars in repairs to your home or having the job done right. The guy that uses no detergent does not know what he is doing.

Check insurance on the guy that uses soaps and then call his references. If he checks out, I'd go with him.

Thanks for your note. The thing is, is that both are licensed, insured and appear to be well employed by both local businesses and my neighbors. I take it, though, in your opinion that detergent and some brightener probably do make a difference?
thanks again -- I will definitely do more inquiries.

It's kinda like you taking a shower....if you don't use soap youre gonna have to scrub harder and harder. With soap it just falls off.
I would insist on bleach (a minimum of 10%) and soap.

If you don't use soap, its not gonna come clean. Period. It's akin to chopping a weed off at the surface. It will grow right back. Unless you use bleach, the mold spores will remain. Unless you use something to emulsify the dirt, it will remain.

Your goal should be to employ the gentlest technique possible. I don't think 10% sodium hypochlorite is neccessary. I never go above a 2% final dilution. We never kill or brown a single blade of grass. It's all in the technique.

The price is the last thing one should worry about. Think about this. Your home is your largest investment. If you decide to cheap out to save a measley $75 you will long forget that bliss of savings when the bitterness sets in after you see mold regrowing before the end of summer.

Thanks for bearing with my cluelessness. This house stuff drives me crazy. Anyway, both of you have convinced me and I will proceed accordingly. Thanks again!