Hello, I own a home that is roughly 80 years old. The foundation is stone with a newer cement floor. On top of the stone foundation there are granite blocks. Portions of the foundation are bulging in and looking unstable. Also, sand is trickling in slowly. What I would like to do is pour a new foundation inside the old one up to the bottom of the granite blocks. Does anyone have experience with this? I have been toying with the idea of doing it my self. I do have some experience with pouring foundations, but fairly limited. My biggest question here though is, if I were to have someone do it what am I looking at for costs, roughly? The dimensions are 40 x 28. Thanks in advance for the help.