Engineers favor deep foundations when there are very large design loads, poor soil at shallow depth or site constraints, such as adjacent structures. Many deep foundations are put in place by driven piles or drilled shafts. And most foundation contractors tend to specialize in one method or the other.
"I grew up in a pile-driving family," says Mike Wysockey, president of Thatcher Foundations Inc., Gary, Ind. "My father took over the firm, which was founded in 1946, in the early 1970s." The pile-driving "market in general has been picking up some, with bigger firms trying to muscle into the deep foundation market. Firms are chasing the work really hard."