Thank you very much, loanwizard and Leahs Mom.
I originally thought cement would be fine as well but read somewhere about how it leaches up moisture & would be terrible for DL method. I was confused then as it seemed like one of the best floors to have under DL (due to it being predator-proof). It even has a few cracks in it already so drainage shouldn't be much an issue.
Thanks for the description Leah's Mom. I'll see about tossing in a bit of dirt to start as well. Although I think I'll add in some dried garlic to ward off mites or whatever. I don't know the soil at all yet - so prevention's better than clean-up!
It will absorb moisture but not all the chickens produce, and if you are concerned about it you could always cover it with a sheet of vinyl flooring, or paint it with garage floor paint. I have a wood floor painted with 2 coats of porch and floor paint, so far it is fine. Only been in the building since April 1 so that can most definitely change, but so far, so good.