Helical Piers and Helical Piles: How They Provide Reliable Foundation Support
Foundation repair often requires transferring the weight of a structure away from weak or unstable soils to material capable of providing dependable support. Helical piers are one method contractors and engineers can use to accomplish this without the extensive excavation associated with some traditional foundation support methods.
Also commonly called helical piles, helical piers are steel foundation elements consisting of a central shaft with one or more helical plates. During installation, the pier is mechanically advanced into the soil until the required installation criteria are achieved.
At ECP, we typically use the term helical pier, particularly when discussing foundation repair and underpinning applications. However, helical pier and helical pile are frequently used interchangeably within the foundation and construction industries.
Understanding how these systems work—and how shaft configuration, helix design, soil conditions, installation torque, and engineering requirements influence their performance—helps contractors select the appropriate solution for each project.
How Do Helical Piers Work?
A helical pier transfers structural loads from the foundation to suitable bearing soils below the structure.
Unlike a driven pile, a helical pier is rotated into the ground. The helical plates attached to the shaft allow the pier to advance through the soil as torque is applied by hydraulic installation equipment.
Additional shaft extensions can be added as installation progresses, allowing the pier to reach the depth necessary to satisfy project requirements.
Once properly installed, the pier is connected to the structure using a bracket or other connection appropriate for the application. Loads can then be transferred from the structure through the pier system and into the supporting soil.
This installation method makes helical piers useful for projects where soil conditions near the surface cannot adequately support the required structural load.
What Determines the Capacity of a Helical Pier?
A helical pier’s capacity isn’t determined by a single characteristic. Several factors can affect system selection and performance, including:
- Soil conditions and strength
- Pier shaft size and configuration
- Number, diameter, and spacing of helical plates
- Installation depth
- Installation torque
- Structural loads
- Pier spacing and placement
- The connection between the pier and structure
- Project-specific engineering requirements
Because these conditions vary from one project to another, helical pier selection should be based on the requirements of the application rather than a one-size-fits-all approach.
That flexibility is one of the primary advantages of a helical foundation system.
Why Installation Torque Matters
One of the distinguishing characteristics of helical pier installation is the ability to monitor installation torque as the pier advances.
The resistance encountered while rotating a helical pier into the soil provides useful information about the soil conditions surrounding the helices. When used with the appropriate system-specific torque correlation and engineering criteria, installation torque can be related to the expected capacity of the installed pier.
For contractors, this provides valuable information during installation rather than relying solely on depth as an indication of suitable support.
Depth alone does not determine whether a pier has achieved the required capacity. Two locations on the same project can encounter different subsurface conditions at the same elevation.
Monitoring torque therefore allows installers to evaluate changing resistance as installation progresses and determine when specified installation criteria have been reached.
The required torque and capacity should always be based on the selected pier system, soil conditions, structural loads, and applicable project specifications.
Round Shaft vs. Square Shaft Helical Piers
Helical piers are available with different shaft configurations, including round and square shafts. The appropriate option depends on the application and subsurface conditions.
Round Shaft Helical Piers
Round shaft systems can provide increased resistance to buckling in applications where the pier passes through soft or weak soils before reaching competent bearing material.
The tubular shaft also provides greater cross-sectional area than an open square shaft, which can be advantageous in certain soil and loading conditions.
Square Shaft Helical Piers
Square shaft helical piers are commonly used in applications where the surrounding soil provides adequate lateral confinement to the shaft. Their configuration can make them well suited to penetrating certain dense or difficult soil conditions.
Neither configuration is universally better. Selecting between round and square shaft systems requires consideration of the soil profile, loading conditions, unsupported shaft length, installation requirements, and engineering design.
How Helix Size and Configuration Affect Performance
The helical plates attached to the pier shaft play a critical role in transferring loads to the surrounding soil.
Helical pier systems may incorporate a single helix or multiple helices of different diameters. The appropriate configuration depends on the load requirements and soil conditions encountered at the site.
Helix diameter affects the amount of bearing area available to transfer loads into the soil. Multiple helices can provide additional bearing area when properly spaced and installed within suitable soil.
However, adding larger or additional helices is not simply a matter of maximizing the size of the pier. Helix configuration affects installation torque and how the pier interacts with different soil layers.
The system should therefore be selected based on site conditions and project requirements rather than assuming that more or larger helices automatically provide the best solution.
Advantages of Helical Piers for Foundation Support
Helical piers offer several practical advantages for foundation repair and construction applications.
Adaptable installation depth: Extensions allow installers to continue advancing the pier when competent bearing material is deeper than initially anticipated.
Real-time installation information: Torque can be monitored during installation and used as part of the process for verifying that specified installation criteria have been achieved.
Relatively compact installation equipment: Helical piers can often be installed using smaller hydraulic equipment than some alternative deep foundation systems, making them useful where site access is limited.
Minimal vibration: Because the piers are rotated rather than driven into the ground, installation typically produces relatively little vibration.
Immediate loading: Helical systems do not require concrete curing before loads can be applied, provided installation and connection requirements have been satisfied.
Configurable systems: Different shaft sizes, helix configurations, extensions, and brackets allow the system to be adapted to a range of soil and structural conditions.
These characteristics have made helical piers a widely used option for both remedial foundation support and new construction applications.
Where Are Helical Piers Used?
Helical piers can be used in a variety of residential, commercial, and light industrial applications.
Depending on engineering requirements and site conditions, applications may include:
- Underpinning settling foundations
- Supporting new foundations
- Foundation additions
- Porches and decks
- Retaining structures
- Equipment or utility supports
- Other structures requiring deep foundation support
The appropriate system depends on the loads involved, soil conditions, structural configuration, and applicable design requirements.
For existing structures experiencing settlement, helical piers can be installed alongside the affected foundation and connected using underpinning brackets. The structural load can then be transferred to the installed pier system.
For new construction, helical piles can be installed before construction and incorporated into the foundation design from the beginning.
Site Conditions and Engineering Matter
The versatility of helical piers does not eliminate the need for proper evaluation and design.
Before selecting or installing a helical system, contractors and project professionals may need to consider soil information, structural loads, foundation condition, access limitations, utilities, groundwater, obstructions, corrosion potential, and applicable building requirements.
Installation records are also important. Documenting information such as pier location, configuration, installation depth, and final torque provides a record of how the system was installed.
For engineered projects, pier selection, capacity requirements, spacing, and installation criteria should follow the project specifications and applicable engineering requirements.
The goal is not simply to install a pier as deeply as possible. It is to install the appropriate foundation element to the criteria required for the project.
ECP Helical Pier Systems
Earth Contact Products manufactures helical pier systems for foundation repair and new construction applications.
ECP’s helical pier product line includes multiple shaft sizes and configurations, allowing contractors and engineers to select systems based on anticipated loads, soil conditions, and project requirements.
Available configurations include round and square shaft systems, shaft extensions, multiple helix diameters and configurations, and connection components for different applications.
ECP manufactures its piering systems using American-made steel and provides technical resources and contractor support for proper product selection and installation.
Rather than approaching every foundation project with the same configuration, the range of available systems gives contractors options for addressing the conditions encountered in the field.
Frequently Asked Questions About Helical Piers
The terms helical pier and helical pile are frequently used interchangeably. Terminology can vary by manufacturer, engineer, region, and application. ECP commonly uses “helical pier,” particularly when referring to foundation repair and underpinning systems.
There is no standard depth that applies to every project. Helical piers are advanced until the installation criteria specified for the project are achieved. Required depth can vary considerably depending on soil conditions, loads, pier configuration, and engineering requirements.
Capacity depends on factors including soil conditions, helix configuration, shaft size, structural loading, and installation characteristics. Installation torque can be correlated with capacity when the appropriate torque correlation for the specific system is used. Project-specific engineering requirements ultimately determine the capacity that must be achieved.
Installation torque can have a relationship with capacity, but the relationship is not universal across every helical pier. The appropriate torque correlation depends on the particular pier system and other design factors. Contractors should follow manufacturer specifications and project engineering requirements when interpreting installation torque.
Neither is inherently better for every project. Round and square shaft systems have characteristics suited to different soil profiles and loading conditions. System selection should account for factors such as soil strength, potential buckling, installation requirements, structural loads, and engineering design.
Helical piers can often be installed using relatively compact hydraulic equipment, making them a practical option for many projects where access for larger foundation equipment is limited. Actual equipment requirements depend on the pier system, required installation torque, site conditions, and available working space.
For projects with especially restrictive access or low overhead clearance, ECP also offers the DRIVECAST® Grouted Displacement Pile. DRIVECAST is designed for challenging applications such as work inside existing structures, basements, congested jobsites, and other locations where conventional deep foundation equipment may be difficult to use. The system also produces minimal spoils and site disturbance during installation.
The helical pier itself does not require a curing period. Once the system has been properly installed, connected, and verified according to project requirements, it can generally accept load without waiting for the type of curing period associated with cast-in-place concrete foundations.
Yes. Helical piers can be used to underpin existing foundations experiencing settlement and can also be incorporated into new construction foundation designs. The pier configuration, connections, installation requirements, and engineering will vary depending on the application.
Installation documentation may include pier location, pier and helix configuration, installation depth, torque readings, extensions used, final installation torque, and other information required by the manufacturer, engineer, or project specifications. Accurate installation records provide valuable documentation of the completed foundation support system.
Choosing the Right Helical Pier System
Reliable foundation support begins with understanding the structure, soil conditions, loads, and installation requirements—not simply choosing the largest available pier.
A properly selected helical pier system gives contractors the flexibility to respond to varying subsurface conditions while providing measurable installation information that can help verify performance.
ECP manufactures a range of helical pier systems and provides contractors with the products, technical resources, and support needed for foundation repair and new construction applications.
For product specifications, system selection, training, or technical support, contact ECP to discuss the requirements of your next project.