In a previous article, we described how our design-build company completed a job using helical piers to support a replacement foundation in unstable soils ("A Pier-and-Beam Foundation for a Coastal Site," 7/08). Early last year, we were called on to stabilize a late-1970s home that was gradually slipping down its sandy 30-degree slope. Despite its precarious state, the owners were still living there, but they were ordered to vacate by the local building commissioner before he issued the permit to repair.

The 26-foot-wide house was built on a narrow basement foundation that had been cut into the slope. The original concrete foundation carried only 10 feet of the total span The rest of the structure was supported on freestanding 4-inch round steel columns on 8-foot centers. These stood on a concrete grade beam, which had been formed on top of fill...

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