A deep foundation is a type of foundation distinguished from shallow foundations by the depth they are embedded into the ground. There are many reasons a geotechnical engineer would recommend a deep foundation over a shallow foundation, but some of the common reasons are very large design loads, a poor soil at shallow depth, or site constraints (like property lines).
There are different terms used to describe different types of deep foundations including piles, drilled shafts, caissons, and piers. The naming conventions may vary between engineering disciplines and firms. Deep foundations can be made out of timber, steel, reinforced concrete and pre-tensioned concrete. Deep foundations can be installed by either driving them into the ground or drilling a shaft and filling it with concrete, mass or reinforced.
Timber Piles: Timber piles can be the most cost effective method to install your foundation for residential and small commercial buildings.
Helical piles: An inexpensive alternate method using drilled piles.
H-Piles: Driven generally for H-beams and lagging systems.