One of America’s premier specialty foundation contractors, Schnabel utilizes underpinning to ensure the structural stability and integrity of existing foundations. An industry leader in safety, we’ve streamlined the task with unique innovations that eliminate the need for manual labor, creating a safer, more efficient process.

Improving the Foundation Underpinning Process

Underpinning is a very effective method used to repair existing foundations or increase foundation depth. It may be necessary for several different reasons, but generally, underpinning is used to lower the bearing level of a foundation to accommodate an adjacent excavation. It may also be necessary when adding an additional story or other weight to a building to improve the existing foundations capacity.

There are a variety of types of underpinning, depending on the goals and circumstances surrounding a project. Schnabel specializes in hand-dug piers, micropiles, bracket piles, jet grouting and other innovative processes for underpinning. As a leading-edge, design-build contractor, Schnabel has also elevated the underpinning process by creating a safer, more efficient way to install underpinning using soil mixing.

A Patented System

While it is a very effective process, underpinning requires expert knowledge and extensive field experience. It can be both time-consuming and dangerous in certain instances, due to the traditional reliance on manual excavation. Because we have always been at the forefront of safety and innovation, Schnabel has invested heavily in research and development to push the underpinning process into the 21st century by making it faster, safer and even more reliable.

We’ve accomplished our goal and exceeded industry expectations with a patented soil mix pier underpinning (SMPU) system (Patent 10,889,955). This development further sets us apart from other specialty foundation and soil retention companies and bolsters our reputation as an industry leader in safety and innovation.

During the underpinning process, Schnabel designs and installs soil mix piers beneath existing structures to extend foundations to deeper stratums. This is a vast improvement on traditional hand-dug piers where workers excavate soil and construct concrete piers beneath a structure. Hand-dug piers are both time consuming and risky to the worker.

At Schnabel, we use a patented method of construction that eliminates the need to put workers under the existing structure. The innovative method utilizes specialized equipment to reach beneath a structure and create a rectangular soil mix pier. The pier is created by mechanically mixing the in-situ soil with cement grout. The mixing is performed with an articulating cutter head. The resulting soil-cement mixture then hardens in place and forms an underpinning pier that can resist vertical loads from the structure above. The soil mix piers can be installed rapidly and can be loaded as soon as 24 hours after installation. This has the potential to shorten project schedules considerably.

Investing in Innovative Underpinning Methods

Soil mix piers provide uniform bearing beneath sensitive structures. Our patented installation method creates rectangular-shaped piers that can be positioned to provide full support to existing footings. This contrasts with the cylindrical-shaped piers that result from conventional methods of creating soil-cement columns such as jet grouting or deep soil mixing.

Soil-cement is a proven and versatile building material with a long history of use in geo-structural applications. Typical unconfined compressive strengths range from 100 to 1,000 psi. Schnabel determines the appropriate ratios of cement and water to be combined with the soil to produce the required strength.

With decades of field experience and a diverse staff of skilled industry experts, Schnabel has the expertise to provide tailored underpinning solutions to strengthen and support existing foundations. We also stand at the forefront of safety and innovation, ensuring that we bring the latest techniques and technologies to every project.

Safety is a top priority at Schnabel. We take a complete systemic approach to safety because of the nature of the work we do. Our safety team is dedicated to reviewing all aspects of construction — prior to, during, and follow-up.

At Schnabel, we work with unique equipment you may not find anywhere else. We also often modify equipment in a way that makes things faster, safer and more efficient. This allows us to eliminate any potential hazards and streamline operational efficiencies.

It also requires substantial, ongoing investment and a continuing commitment to hiring the very best the industry has to offer. This makes Schnabel a great place to work, while also positioning us as a thought leader and industry innovator that can provide unique solutions in a timely manner, regardless of the complex challenges and environmental complications surrounding a particular project.

At Schnabel, if there’s a safer, more efficient way to do something for a customer, we will always find a way to do it. To learn more about our innovative underpinning construction process, contact our office today.


Schnabel is the sector’s most operationally efficient Geostuctural 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.