We just purchased a c1910 home in Plainfield, NJ. The concrete basement floor has some crumbling and heaving, so my husband took a jackhammer to some parts and discovered that the slab is only 1/2 to 1 inch thick with compacted dirt underneath. That would explain why there is dampness in the floor. Is this structurally sound? I thought that concrete floors needed to be 4 inches thick. Is the floor okay to be left as it is? What would be the process of fixing it? Does anyone know approximate cost persquare foot? Thanks so much for your help!