The advantages of a bored pile foundation include its suitability in soft, unstable environments and its maximum drilling depth. Bored pile foundations are useful when the ground contains multiple rock layers of varying consistency. About.com expert Juan Rodriguez explains that these deep piles also reach below the frost line, which is an important advantage in cold climates. Each variety of bored pile foundation is suited to particular geologic conditions.
According to AGRA Foundations, underreamed bored piles have slender shafts and large, flat bases that distribute the weight of the piles over a large area. This type of bored pile foundation is stable in soft soils.
Another type of bored pile foundation is the augercast pile. Construction workers use large augurs to bore deep into the ground. As the augur turns, it transports excavated soil up to the ground level. Workers then fill the hole with cement. Augercast pile boring is unsuitable for contaminated soils because this technique produces huge amounts of waste soil.
Bored pile foundations that are used to support piers frequently feature heavy steel girders laid horizontally between adjacent piles. This adds strength and increases the foundation's weight-bearing area. This technique sometimes appears in residential land construction. In those cases, wooden beams take the place of metal girders.
The length, width, depth and style of bored pile foundations depend on the specific project and the surrounding environment. When the project calls for extreme loads, each pile receives a tight-fitting rebar cage. This strengthens the foundation and adds stability in loose, soft or moist ground.