One of the nation’s most accomplished specialty foundation contractors, Schnabel utilizes underpinning to ensure the stability and integrity of an established foundation.

Underpinning is used to lower the bearing level of an existing foundation, typically to accommodate an adjacent excavation. Schnabel specializes in hand-dug piers, bracket piles, micropiles, jet grouting and other innovative systems for underpinning.

With decades of field experience, Schnabel has the expertise to provide tailored underpinning solutions to support and strengthen your existing foundations.


Underpinning is used to transfer the load from an existing structure’s current foundation level to a deeper level in the ground. There are several reasons why this construction may be required. Often an excavation for a new structure will occur within feet or inches of an existing foundation, and the bottom of the new excavation will be lower than the bottom of the existing foundation. To prevent damage to the existing structure, its foundation may need to be extended to an elevation below the bottom elevation of the proposed excavation using underpinning.

Another use for underpinning is to mitigate settlement of existing foundations. Underpinning construction can be used to transfer the foundation load to a deeper and more competent soil stratum. This same method of load transfer can be used if there is a desire to add additional load to an existing structure in excess of the capacity of the existing foundations.

One of the most accomplished nationwide underpinning construction contractors, Schnabel has decades of experience in the design and construction of hand-dug piers, bracket piles, micropiles and other systems used to underpin structures. More recently, Schnabel has also used jet grouting, Soil Mix Pier Underpinning and soil mixing for underpinning. 

underpinning construction

Schnabel’s design-build approach to underpinning combines regular monitoring with close communication between our experienced engineers and field staff. This allows us to keep the movements of some very sensitive structures well within acceptable limits.

A premier earth-retention contractor, Schnabel can help you achieve your project goals. To learn more about underpinning construction, contact our office today.




Illinois State Capitol Phase IV | Springfield, IL

As part of the Illinois State Capitol Phase IV project, Rivercity Construction and Core Construction contracted Schnabel to provide underpinning services. The underpinning was constructed using both mechanically-dug and hand-dug pits backfilled with concrete and grout. Schnabel installed a total of 880 square feet of underpinning to reinforce and fortify the Capitol Building’s stone block foundation.

underpinning contractors

Reno ReTRAC | Reno, NV

As part of the Reno ReTRAC project, Schnabel designed and constructed a complex excavation support and underpinning system. A method using a combination of hand-dug piers and micropiles was used to support the adjacent structures. This project was awarded the 2006 Outstanding Project Award by the Deep Foundations Institute (DFI)

Schnabel was part of Granite’s design-build team that constructed a depressed 2-mile long railroad trench through the center of Reno that eliminated many at-grade RR crossings. Schnabel installed temporary shoring for the trench excavation and where the trench walls needed to be installed below existing structures, Schnabel constructed permanent hand-excavated reinforced concrete underpinning piers below the groundwater table through boulders up to 8 ft in diameter. Schnabel received Deep Foundation Institute’s Outstanding Project Award for its work on this project.
Claus Ludwig, P.E, RenoRETRAC Project


Schnabel is the sector’s most operationally efficient Geostructural Design & Construction contractor. We optimize efficiencies by leveraging decades of experience and design/build expertise to innovate processes and approaches that are consistently proven to deliver optimal outcomes for our clients.