I have been posting sporadically here for the past year as I work through my DIY crawlspace-to-basement project. I am just about ready for my concrete floor which incidentally will be the first thing I'll not be doing myself for obvious reasons.
I've spent some time on Angie's List and found a concrete company that had a large number of very positive reviews. They came out to do an estimate yesterday. I asked a number of questions that they answered to my satisfaction. However, they told me a couple things that I was a bit unsure of and I'm wondering if I could get a second opinion here.
The first regards sub base. The current surface of the grade happens to be at the level where the bottom of the slab will start. However, I mentioned that my plan is do dig down another 3"-4" and put down a gravel sub base to act as a capillary break followed by a vapor barrier. The guy said that since the current surface is virgin soil and is dry despite the unusually very wet June and July we've been having, he said not to bother with the sub base a just put the vapor barrier on the virgin soil (clay). Everything I've been reading suggests a gravel or crushed stone sub base. Is that really overkill like the concrete guy said? He knows I would be doing that part myself so it would make no difference in his work.
The second issue regards reinforcement. His recommendation is to go with a 4000 psi mix with fiber and to forgo any rebar or remesh. Is that a good idea? The slab thickness will be 3.5".
Unfortunately, I'm having a tough time getting anyone else to come out for an additional estimate. I'm kind of off the beaten path where I am.
P.S. Just for kicks I'm attaching a picture of where I am currently (disregard the mess