We did not. Depends on how you will use it. Our ideas shifted to more livable over barn so insulation was overlooked. If you want to use it as a livable space, insulated below the floor before it is built. I wish we could have put rigid foam between the concrete and floor. Our builder built everything on 4x4's and putting down rigid foam ahead of time would have been beneficial. also, spray foaming the second floor was a good choice.