Expert Underpinning Solutions for Structural Stability
Strengthening and Supporting Existing Foundations with Proven and Innovative Methods.
As one of the nation’s most accomplished specialty foundation contractors, Schnabel delivers expert underpinning services to ensure the stability and integrity of existing structures. Whether it’s lowering the bearing level of a foundation to accommodate an adjacent excavation, mitigating settlement, or increasing load capacity, our tailored solutions provide long-term reliability and performance.
How Underpinning Works
Underpinning transfers the load from an existing structure’s current foundation to a deeper, more competent stratum. It is often required when:
- A new, deeper excavation is constructed near an existing foundation.
- An existing structure shows settlement and requires stabilization.
- Additional loads (such as new stories) exceed the capacity of current foundations.
Schnabel offers a full range of underpinning systems, including:
- Hand-Dug Piers – Ideal for sensitive structures and confined spaces.
- Bracket Piles & Micropiles – Efficiently transfer loads to deeper, stronger soils or rock.
- Additional loads (such as new stories) exceed the capacity of current foundations.
- Jet Grouting – Forms high-strength soilcrete columns for load transfer.
- Soil Mixing – Enhances ground conditions beneath existing foundations.
- Soil Mix Pier Underpinning (SMPU) – Schnabel’s patented system for safer, faster, and more reliable underpinning.
Our design-build approach integrates real-time monitoring and close coordination between our engineers and field teams to keep even the most sensitive structures stable and protected during construction.
Need expert underpinning for your project? Let’s discuss how Schnabel can strengthen and protect your foundation with proven methods.
Patented Soil Mix Pier Underpinning (SMPU)
Schnabel has redefined underpinning with its patented Soil Mix Pier Underpinning system (Patent 10,889,955). Traditional hand-dug piers can be time-consuming and hazardous; SMPU eliminates those risks while delivering superior performance.
How SMPU Works
Specialized equipment reaches beneath existing structures to create rectangular soil mix piers.
In-situ soil is blended with cement grout using an articulating cutter head.
The soil-cement mixture hardens in place, forming rigid piers that resist vertical loads.
Piers can be loaded within 24 hours, significantly reducing project schedules.
Advantages of SMPU
- Safer – Eliminates the need for workers under existing structures.
- Faster – Higher production rates and immediate load capacity.
- Precise – Rectangular piers provide uniform bearing beneath footings.
- Proven – Soil-cement delivers compressive strengths from 100–1,000 psi.
Why Schnabel?
Here’s why clients choose Schnabel:
Partner with Schnabel to safeguard your structure with underpinning solutions built for long-term stability.
Real-World Results in Underpinning
Projects Schnabel Has Worked On
Here are some projects where Schnabel’s underpinning solutions played a key role:
CoStar Richmond Campus Project
Location:
Richmond, VA
Client:
Whiting-Turner Contracting Company / CoStar Group, Inc.
Background
CoStar expanded its Richmond campus with a two-building complex, including a four-level subterranean parking garage adjacent to the existing building.
Schnabel’s Solution
Schnabel installed a temporary excavation support system, including 5,700 LF of cased soldier beams, 34,000 SF of lagging, and 310 tiebacks. The adjacent building was underpinned with 2,450 SF of SMPU. Work required navigating underground obstructions and hazardous soils.
Results
The support system and SMPU underpinning were completed safely, on schedule, and on budget, enabling construction of the parking garage.
Illinois State Capitol – Phase IV
Location:
Springfield, IL
Client:
Rivercity Construction and Core Construction
Background
As part of the Illinois State Capitol Phase IV renovation project, underpinning solutions were required to support the historic 155-year-old structure.
Schnabel’s Solution
Underpinning was constructed using both mechanically-dug and hand-dug pits, which were then backfilled with concrete and grout. In total, Schnabel installed 880 square feet of underpinning to reinforce and fortify the Capitol Building’s stone block foundation.
Results
The foundation was successfully stabilized, ensuring long-term structural integrity of the historic building.
Ready to strengthen your structure with proven underpinning solutions?
Partner with Schnabel to ensure your foundation is supported safely, efficiently, and with innovative methods that deliver lasting results.