Choosing the Ideal Size: Helical Pier Size Selection

Helical Pier Sizes: How Capacity Really Works

When someone asks, "What size helical pier do I need?", the answer is almost never as simple as choosing a larger shaft or a bigger helix.

In reality, selecting the proper helical pier is an engineering decision that balances structural strength, soil conditions, installation equipment, and the loads applied by the structure. While larger piles generally provide higher capacities, the strongest helical foundation isn't necessarily the biggest one—it's the one designed specifically for the project.

At Structural Anchor Supply, we help contractors, engineers, and owners understand how helical pier size affects performance without overspending on unnecessary steel or under-designing a critical foundation.

Helical Pier Size Is More Than Diameter

Many people assume the diameter of the shaft determines capacity.

While shaft size certainly matters, a helical foundation is actually made up of three primary components working together:

• Helical bearing plates (helices)

• Structural steel shaft

• Connection between the pile and the structure

Each component must be properly matched so the system performs as intended. The helices transfer load into competent bearing soils, the shaft carries the load through the weak soils, and the connection transfers structural loads into the pile.

Think of it as a chain.

The system is only as strong as its weakest link.

Capacity Depends on the Soil

This is perhaps the biggest misconception surrounding helical piles.

A large pile installed in poor soil may support less load than a smaller pile installed into dense bearing soils.

Unlike shallow foundations, helical piles transfer loads to competent bearing strata located well below the surface. Engineers evaluate the geotechnical report to determine where those bearing layers exist before selecting the proper pile configuration.

This is why two identical buildings in different locations may require completely different pile designs.

Common Helical Pier Categories

Although every project is unique, helical piles generally fall into three categories.

Light-Duty Foundations

Typically used for:

• Decks

• Residential additions

• Boardwalks

• Small utility structures

• Solar equipment

These applications generally involve relatively low design loads and are commonly installed with smaller installation equipment.

Medium-Duty Foundations

Common applications include:

• Commercial buildings

• Equipment foundations

• Light industrial facilities

• Canopies

• Modular buildings

These projects often require larger shaft sections and multiple helix configurations to achieve the required design capacity.

Heavy-Duty Foundations

Heavy civil and industrial projects may require substantially larger round shaft piles designed for:

• Electrical substations

• Transmission structures

• Industrial facilities

• Manufacturing plants

• Heavy equipment

• Bridges

• Renewable energy projects

These foundations are engineered for significantly higher compression, uplift, and lateral demands while accommodating challenging soil conditions.

Square Shaft vs. Round Shaft

One of the most important design decisions is selecting the proper shaft type.

Square Shaft

Square shaft helical piles are commonly used where:

• Higher uplift resistance is required

• Moderate compression loads exist

• Smaller installation equipment is preferred

• Residential and light commercial projects dominate

Their solid shaft provides excellent performance in many tension applications.

Round Shaft

Round shaft piles are generally selected when projects require:

• Higher compression capacity

• Greater bending resistance

• Larger structural loads

• Heavy commercial and industrial applications

Larger round shafts also accommodate higher installation torque and are frequently specified for substations, industrial buildings, bridges, and utility infrastructure. The Chance product line includes multiple round shaft diameters to address a wide range of structural demands.

Installation Torque Matters

One of the advantages of helical foundations is that installation provides valuable feedback about the soil.

As the pile advances into the ground, installation torque generally increases as stronger bearing soils are encountered. Properly calibrated torque measurements are one of the tools engineers use during installation to help verify that the pile has reached suitable bearing conditions. However, installation torque is only one part of the overall design and verification process.

This makes helical piles different from many other deep foundation systems because performance can be evaluated during installation rather than after the foundation is complete.

Bigger Isn't Always Better

One of the most common mistakes is assuming that specifying the largest available pile automatically creates the best foundation.

Oversizing can increase:

• Material cost

• Equipment requirements

• Installation time

• Overall project cost

Conversely, undersizing may require redesign, additional piles, or reduced performance.

The most economical solution is typically the smallest helical pile that safely satisfies both the structural and geotechnical requirements.

Engineering Drives the Design

Professional engineers evaluate numerous factors before selecting a helical pile system, including:

• Dead loads

• Live loads

• Wind forces

• Seismic loads

• Soil borings

• Groundwater conditions

• Corrosion considerations

• Lateral loading

• Buckling potential

• Installation access

• Long-term service requirements

Successful designs balance both the structural strength of the pile and the geotechnical capacity of the supporting soils while considering installation constraints.

Why Contractors Work with Structural Anchor Supply

Selecting the right helical pile is about more than choosing a part number.

Our team helps contractors and engineers identify solutions that fit the project—not just the catalog. Whether you're supporting a residential addition or designing foundations for an electrical substation, we can assist with product selection, engineering support, installation guidance, and CHANCE® product availability.

Because every site is different, the best foundation begins with the right engineering and the right partner.

Need Help Selecting the Right Helical Pier?

Structural Anchor Supply supplies CHANCE® Helical Foundation Systems throughout the Upper Midwest and Rocky Mountain regions. Our team works with contractors, geotechnical engineers, and structural engineers to identify the appropriate helical foundation solution for projects ranging from residential repairs to heavy industrial construction.

Contact Structural Anchor Supply today to discuss your next project or request engineering assistance with helical pile selection.