In August, some poorly skilled contractors installed a concrete radiant floor system in my little weekend house in the Catskills. The floor has a nearly 2 inch differential in height and has a sandy, gritty texture--if you scape your shoe across it, you could dig all the way to the bottom. I have since fired the bad guys. One contractor after another came and inspected their work and told me how bad it was (one fellow said I "should shoot them!" the work was so appalling.). Though the work is horrible, the floor does generate heat. I've nearly figured out a way to cover the floor to make it liveable and would like to use the system if at all possible. (Some of the folks who have looked at the job are afraid that if I remove the concrete, it'll damage the house.) However, the last P.E. I had look at the job--concrete isn't his specialty--said he was worried for me that over the course of a year or two with expansion and contraction, the concrete would seriously crack. I have one crack already across a doorway, which may just be the house shifting, but there is another one started elsewhere. Is sandy, gritty, poor quality concrete likely to seriously crack over time? I've put in a call to my structural engineer about this and he's trying to find out, but I wondered if anyone else could give me guidance. Thanks much.