Site conditions influence whether wood or masonry piles with concrete footings will provide enough structural support or whether helical steel piles, which are installed in sections, are called for.
The optimal solution in unstable soils, such as sand or peat, these are made from short—about 5 feet long—steel segments bolted end-to-end on-site. They get rotated into the ground by machine (as shown) and can be installed where traditional wood piles cannot fit under an existing house. Screw-like plates (inset) cause less soil disturbance than traditional excavation. The piles can be tied directly into the building structure or into conventional concrete footings.