Foundation Underpinning Foundation underpinning is a general term that refers the process of extending a foundation to deeper levels. Foundation underpinning is commonly done to strengthen a building that may be settling into the ground. Foundation underpinning can be performed by a wide variety of “Geotechnologies”, including: Helical piles Push piles Drilled piles Pit underpinning. EFT strongly advises clients to conduct a subsurface investigation prior to having underpinning work done. Each underpinning system has distinct advantages/disadvantages and should only be performed with site-specific parameters.