I have a house that was build really well in the 50's, but everything done after that, including an added enclosed patio was done poorly. The patio is about 10 feet deep and 20 feet wide. I just finished replacing the windows and siding for the house and patio. Now I pulled up the floor in the patio and found that the floor is cracked from sinking. One small section is still in good shape because it was poured over the old concrete stoop leading from the back door. The rest has sank about 4 or 5 inches. I had an animal digging under the patio a few years ago and have since then covered up the hole and not had any more animal problems. But I believe there is no footing or at least not a good one. I also think a portion of the patio is just floating now. I thought about pouring a concrete mixture over the top to level everything off, but I know it will continue to sink and crack. A contractor suggesting cutting out the floor as close to the walls as possible and pouring a new floor. I'm still worried that the old concrete will continue to sink and crack the new concrete or separate from the new concrete. Is there anything that can be done shy of tearing down and pouring a new foundation? If I jack up the structure to pour a new foundation, I am affraid the new windows (which are now level) will crack. Can I add pilings to support the walls? Or can I use rebar to structurely connect the old to new concrete? Any help is appreciated.