Push Piers for Foundation Repair: How They Work, Applications, and Benefits
Foundation settlement can lead to visible problems throughout a structure, including cracked walls, sticking doors and windows, uneven floors, and separation around doors, windows, or other building components.
But repairing these symptoms alone does not address the underlying problem when the foundation itself is continuing to settle.
Push piers are a deep foundation underpinning solution used to stabilize existing foundations affected by settlement. Rather than relying on inadequate near-surface soils, push piers transfer structural loads to more competent material at greater depth.
For contractors, understanding how push piers work—and how structural loads, soil conditions, installation resistance, foundation condition, and project requirements affect the system—is essential to determining when push pier underpinning is an appropriate foundation repair solution.
What Are Push Piers?
Push piers, sometimes called resistance piers, are steel foundation elements installed alongside an existing foundation.
A typical push pier system consists of steel pier sections and a foundation bracket that connects the pier to the structure. During installation, hydraulic equipment advances the pier sections into the ground using the weight of the existing structure as the reaction force.
Additional pier sections are installed as necessary until the required installation criteria are achieved.
Once installation is complete, the structural load is transferred through the foundation bracket and pier system to competent load-bearing soil or material below the problematic near-surface soils.
This ability to bypass unstable or compressible soils is what makes push piers an effective underpinning option for many existing structures experiencing foundation settlement.
How Do Push Piers Stabilize a Settling Foundation?
Foundation settlement often occurs when the soils supporting a structure can no longer adequately carry its load.
This can happen for a variety of reasons, including:
- Poorly compacted fill soils
- Changes in soil moisture
- Shrink-swell soil behavior
- Consolidation of underlying soils
- Erosion or loss of supporting soil
- Changes in drainage around the structure
- Soil conditions that were inadequate for the original structural loads
When settlement is ongoing or the supporting soils are inadequate, repairing cracks or other cosmetic symptoms does not address the source of the movement.
Push piers provide a new load path.
Instead of continuing to depend on the problematic soil immediately beneath the footing, loads are transferred through the steel pier system to suitable bearing material at greater depth.
The objective is to stabilize the affected portion of the foundation and reduce the potential for continued settlement.
When Are Push Piers a Good Foundation Repair Solution?
Push piers are commonly used to underpin existing structures experiencing foundation settlement.
Potential applications can include:
- Residential foundations
- Commercial buildings
- Settled portions of existing structures
- Structures supported by inadequate near-surface soils
- Foundations where access permits excavation and bracket installation
- Projects where the existing structure provides sufficient reaction for pier installation
That final consideration is particularly important.
Unlike a helical pier, a push pier is hydraulically advanced using the existing structure as the reaction force. The structure must therefore have sufficient weight and be capable of safely resisting the forces involved during installation.
Push piers are not automatically appropriate simply because a foundation has settled. Foundation condition, structural loading, soil conditions, access, and project requirements should all be evaluated before selecting an underpinning method.
How Are Push Piers Installed?
Push pier installation generally begins with excavation alongside the affected foundation to expose the footing or appropriate connection area.
While specific procedures depend on the system and project, the process generally involves several stages.
1. Access the Foundation
Soil is excavated at each planned pier location to provide access to the foundation. The amount of excavation required depends on the foundation configuration, bracket system, site conditions, and installation requirements.
2. Prepare the Foundation
The exposed foundation is prepared as required for the underpinning bracket. Proper preparation is important because the bracket ultimately creates the connection between the existing structure and the installed pier.
3. Install the Foundation Bracket
The push pier bracket is positioned and secured according to the requirements of the system and project.
4. Advance the Pier
Steel pier sections are hydraulically advanced into the soil. The existing structure provides the reaction force necessary to push the pier downward.
Additional sections are added as installation progresses.
5. Achieve the Required Installation Criteria
Installation continues until the required resistance, depth, or other project-specific criteria have been satisfied.
This is an important distinction: push piers are not simply driven to a predetermined depth.
Actual installation depth can vary from one project to another—and even from one pier location to another on the same structure—because subsurface conditions vary.
6. Transfer the Structural Load
Once the piers have been properly installed, the structural load can be transferred to the pier system through the foundation brackets.
If lifting or elevation recovery is part of the repair plan and conditions permit it, that process may also occur during this stage.
7. Document and Complete the Installation
Installation information is recorded as required, excavations are backfilled, and disturbed areas can be restored.
How Deep Do Push Piers Go?
There is no universal depth for a push pier installation.
A pier should not be considered successful simply because it has reached a certain number of feet below the foundation. The necessary depth depends on the subsurface conditions and installation requirements of the project.
One pier may encounter suitable resistance at a different depth than another pier only a short distance away.
This is why contractors should focus on installation criteria rather than depth alone.
Pier sections allow the system to continue advancing through unsuitable soils until the specified conditions are achieved.
How Is Push Pier Installation Verified?
One of the important aspects of professional push pier installation is monitoring what occurs as the pier is advanced.
Hydraulic pressure and the corresponding installation force provide contractors with information about the resistance encountered by the pier.
However, installation pressure should not be viewed in isolation. The relationship between hydraulic pressure and applied force depends on the installation equipment and system being used, and allowable forces can also be limited by the structure itself.
The required installation and verification procedures should therefore follow the push pier manufacturer’s requirements, applicable engineering specifications, and conditions of the individual project.
This is another reason proper system selection and trained installation matter. A push pier is part of an engineered load-transfer system—not simply a steel pipe pushed into the ground.
Stabilizing vs. Lifting a Foundation
One of the most important distinctions in foundation underpinning is the difference between stabilization and lifting.
The primary objective of a push pier repair is generally to stabilize the affected foundation by transferring loads to suitable bearing material.
In some situations, hydraulic equipment may also allow contractors to recover some of the settlement and move the structure toward a previous elevation.
However, lifting should not be assumed to be appropriate or achievable on every project.
Several factors can influence whether elevation recovery should be attempted, including:
- The condition of the foundation
- Amount and duration of settlement
- Structural configuration
- Building materials and finishes
- Plumbing and utility connections
- Adjacent portions of the structure
- Potential for damage during movement
- Engineering and project requirements
A structure that has settled gradually over many years may have adapted to its current position. Attempting to return it completely to its original elevation could create additional problems.
For that reason, successful stabilization does not necessarily mean restoring a foundation to its exact original elevation.
The repair objective should be determined based on the condition of the structure and requirements of the project.
What Are the Benefits of Push Piers for Foundation Repair?
When conditions are appropriate for their use, push piers offer several advantages for underpinning existing foundations.
Deep Foundation Support
Push piers can extend beyond weak or unstable near-surface soils and transfer structural loads to more suitable material at depth.
This addresses the foundation support problem rather than simply repairing visible symptoms of settlement.
Adaptable Installation Depth
Pier sections can be added as installation progresses, allowing the system to respond to subsurface conditions encountered in the field.
Contractors aren’t limited to a fixed pier length established before installation begins.
Relatively Small Installation Footprint
Push pier installation requires excavation at each bracket location, but it can often be performed without the extensive excavation that would be required to remove and reconstruct large portions of an existing foundation.
Actual access and excavation requirements vary by structure and site.
Installation Data
Hydraulic installation provides measurable information that can be documented during the project and evaluated against the requirements of the system and repair design.
Immediate Load Transfer
Push piers do not rely on poured concrete around the pier to develop their primary support capacity. Once the system has been properly installed, verified, and connected, structural loads can be transferred to the pier system according to project requirements.
Potential for Elevation Recovery
Where the structure and project conditions permit, push pier systems can provide contractors with the ability to recover some foundation settlement in addition to stabilizing the structure.
Again, stabilization and lifting should be treated as separate objectives, and elevation recovery should not be promised for every project.
Push Piers vs. Helical Piers: What’s the Difference?
Push piers and helical piers can both be used to transfer structural loads to suitable bearing soils, but they are installed differently and have characteristics suited to different applications.
Push Piers
Push piers are hydraulically advanced into the soil using the existing structure as the reaction force.
Because of this, push piers are primarily associated with underpinning existing structures. The weight and condition of the structure are important considerations when determining whether the system is appropriate.
Helical Piers
Helical piers have one or more helical plates and are mechanically rotated into the soil using hydraulic installation equipment.
Their installation does not rely on the weight of an existing structure to advance the pier. This allows helical piers to be used for both existing foundation underpinning and a variety of new construction applications.
Installation torque also provides information that can be correlated with capacity when the appropriate system-specific criteria are used.
Which Foundation Pier Is Better?
Neither system is universally better.
The appropriate foundation support system depends on factors such as:
- Existing vs. new construction
- Structural weight and condition
- Soil profile
- Required capacity
- Foundation configuration
- Installation access
- Subsurface conditions
- Project objectives
- Engineering requirements
A contractor should evaluate these conditions before determining whether push piers, helical piers, or another repair method is appropriate.
What Should Contractors Consider Before Installing Push Piers?
Successful underpinning starts before the first pier is installed.
Contractors and project professionals may need to consider:
- Evidence and extent of foundation settlement
- Structural condition of the foundation
- Building loads
- Soil and subsurface conditions
- Location of underground utilities
- Access for excavation and hydraulic equipment
- Bracket placement
- Pier spacing
- Nearby foundations and structures
- Plumbing and utility connections
- Drainage and groundwater conditions
- Project engineering requirements
- Applicable codes and specifications
Understanding why the foundation settled is also valuable.
Installing piers can address inadequate foundation support, but other site conditions—such as poor drainage—may still need to be corrected as part of a comprehensive solution.
Why Push Pier Installation Documentation Matters
Installation records provide valuable information about the completed underpinning system.
Depending on the system and project requirements, contractors may document:
- Pier identification and location
- Pier spacing
- Bracket type
- Number of pier sections installed
- Total installation depth
- Hydraulic pressure or installation force
- Final installation readings
- Load-transfer information
- Elevations before and after the repair, when applicable
- Site observations or unusual conditions encountered during installation
Accurate documentation provides a record of the work performed and allows relevant installation information to be reviewed by contractors, engineers, and other project stakeholders.
Contractors should follow manufacturer instructions and project-specific requirements when determining what information must be recorded.
ECP Push Pier Systems for Foundation Repair
Earth Contact Products manufactures push pier systems for professional foundation repair and underpinning applications.
ECP’s push pier systems are designed to give foundation repair contractors options for addressing different structural loads, foundation configurations, and project conditions.
But the performance of any underpinning system depends on more than the steel itself.
Proper evaluation, system selection, bracket placement, installation, load transfer, and documentation all contribute to a successful foundation repair. ECP supports contractors with foundation repair products as well as technical resources and training designed around professional installation.
For current capacities, dimensions, bracket options, installation requirements, and other technical specifications, contractors should reference ECP’s current documentation for the specific push pier system being considered.
Frequently Asked Questions About Push Piers
A push pier is a steel deep foundation element used to underpin and stabilize an existing foundation. Pier sections are hydraulically advanced into the soil using the structure as a reaction force. Once properly installed, the system transfers foundation loads through a bracket and pier to suitable bearing material at greater depth.
The terms are often used to describe the same general type of hydraulically installed underpinning system. Terminology can vary by manufacturer and within the foundation repair industry.
There is no standard depth for every installation. Push piers are advanced until the installation criteria specified for the system and project are achieved. Soil conditions can cause installation depths to vary between projects and between individual pier locations.
Push piers are designed to provide long-term structural support by transferring foundation loads to suitable bearing material. Long-term performance depends on proper evaluation, system selection, installation, structural connection, site conditions, and compliance with applicable project requirements.
Push pier systems may allow some elevation recovery when structural and project conditions permit. However, stabilization is generally the primary objective. The amount of lift that is safe or achievable depends on the condition and configuration of the structure and should be evaluated for the individual project.
A push pier is hydraulically advanced using an existing structure as the reaction force. A helical pier is mechanically rotated into the soil and does not require the weight of an existing structure for installation. This is one reason helical piers can also be used for many new construction applications.
Push piers are primarily used to underpin existing structures because installation relies on the structure to provide reaction force. Helical piers and other deep foundation systems are generally better suited to applications where the structure has not yet been built.
Push piers can be installed through a variety of soil conditions, but no foundation system is appropriate for every site. Soil profile, obstructions, required loads, installation resistance, foundation condition, and engineering requirements should be considered when selecting a repair method.
Excavation is generally required at each pier location to expose the foundation and provide access for bracket installation. The size and location of these excavations depend on the foundation, bracket system, equipment, and site conditions. Push piers can often be installed with less excavation than extensive foundation reconstruction, but they should not be described as requiring no excavation or property disturbance.
Installation time varies based on the number of piers, foundation configuration, required excavation, access, soil conditions, installation depth, and other project requirements. Rather than assuming every project can be completed within a specific timeframe, contractors should evaluate the conditions of the individual structure.
Installation records may include pier locations, bracket information, number of pier sections, installation depth, hydraulic pressure or force, load-transfer information, elevations, and other measurements required by the manufacturer or project specifications
Choosing the Right Foundation Support System
Push piers provide contractors with an effective method for stabilizing many existing foundations affected by settlement, but successful foundation repair begins with understanding the structure and the conditions beneath it.
Foundation condition, structural loads, soil conditions, installation resistance, bracket selection, site access, and engineering requirements all play a role in determining the appropriate solution.
That is why foundation repair should be approached as a system rather than a single product.
ECP provides professional contractors with push pier systems, helical pier systems, brackets, technical resources, and training for a range of foundation repair applications.
Need help selecting a push pier system for your foundation repair projects? Connect with ECP to learn more about our foundation repair products, technical resources, training, and contractor support.