This Window seat area's foundation wasn't tied into the main foundation with rebar. The result, the foundation sunk and moved away from the house. The bottom plate of the wall had lifted off the stem wall of the concrete. The fix: I poured non shrink grout under the bottom plate of the wall so that it was bearing solid on the foundation again. I dug out out the dirt at the corners of the foundation and epoxied in rebar in both foundations, and poured concrete box . The result was the foundation was now tied together by the concrete and the rebar. For the floor on the inside, I used gypcrete to bring the subfloor up to level.