Many of the houses I've worked on as a builder on Cape Cod, Mass., date from the mid-1800s. Most of these houses were built on unexcavated ground. The typical foundation of the era consisted of a shallow stone or brick perimeter, quite often with only a brick or two into the grade, and no footing. These rudimentary foundations are called crawlspaces, but only for lack of a better name, since the clearance under the floor joists is often no more than 6 inches. Because the predominant soil in the area is clean, free-draining sand, it isn't unusual to find one to two-hundred-year old wood in remarkably good