In a week or two, a concrete contractor will be coming to pour a new floor in our existing garage. He is recommending 4" cement, 4000 grade, with mesh, and no rebar. We are also asking him to pour about 450 sq ft more than originally proposed. Question #1: His revised estimate is about $2000 more for the additional footage; does that seem reasonable? Question #2: This project is being done because we had major cracks in the floor. We don't want them again. He wouldn't guarantee there would not be cracks, and said that he'd put in expansion joints. He suggested that a thicker floor, rebar, etc. would not help guarantee against cracks. Is that true? This contractor came highly referred, and I would like to trust him, but now that his bid went from $7500 to $9500, I feel like I need to confirm that I'm not getting taken.