A large part of my business as a foundation contractor in northern California is replacing foundations. Many of these foundations are intact, but are built of unreinforced masonry that is inadequate to support future loads from expected earthquakes or a major renovation. The foundation may already show signs of distress, whether it is from seismic activity or just bad drainage. This distress often shows up when siding is pushed out of plumb and cripple-wall studs no longer bear on the concrete, because the foundation has "rolled" (Figure 1, next page). In other cases, a grade beam may be cracked into separate pieces in several locations. Such problems justify the replacement of the distressed section of foundation. In this article
