I visited some folks this weekend who live back up in the hills in a northern county. He was doing a foundation repair on his house.

The old foumdation was shallow, un-reinforced with steel, and cracked.

The room involved was a nonconforming low-ceilinged room, with wood floors with lots of earth contact and a musty odor of rotting wood.

My friends solution was to excavate inside the cracked foundation 12" below the bottom 

of the old foundation, undermine it by 2", form & pour a new 6"x 24" concrete footing the length of the room. ~9'