John Lisle | Updated October 6, 2022 | Helical Pier Foundation Science

You might already know this, but the United States is a pretty big place. We have nine time zones, eight climate zones (ranging from subarctic to desert), and over 3.7 million square miles of land.

In terms of weather, we see it all here. Blistering heat, blinding snow, pounding rain, violent tornadoes, brutal hurricanes, and even more than that. The climate corrodes, rusts, or rots nearly everything we build.

And few things have a tougher life than the foundations beneath our feet.

The foundations under buildings and structures face a savage range of hard conditions. In vast swaths of the U.S., expansive soils shrink and swell with moisture and drought. Regions with lots of rainfall often have wet soils that are prone to movement. The western parts of the country often have dry soils that are tough to excavate and build on.

Thanks to modern construction, we’ve been able to build in practically every single environment the continental U.S. can throw at us. Places that even 50 years ago would have been difficult to access are now open to development. 

The construction of the Alaska Highway in 1942, finished in just over 8 months, was a sign of humanity’s growing hunger for construction in the most remote locations

That means we demand more from our building foundations than ever. Not only are we constructing more projects in more places, our timelines are shorter than they’ve ever been. We need strong foundations faster, but they also need to be durable and last for a long time.

This brings us to one of the most common questions I get asked when it comes to helical pier foundations. From oil and gas pipelines to foundations for renewable energy and utilities, seems like everyone wants to know…

“How long will my helical pier foundation last?”

It’s a great question, but it turns out the answer isn’t quite so simple.

Helical Pier Lifespan and Durability

I’d love to say there’s a simple answer to the question of how long a helical pier foundation can last in the United States, but there isn’t. If there was a simple answer, I wouldn’t have needed to write this blog article!

There’s many factors that influence the ultimate lifespan of a helical pier foundation, and some of them will have a larger impact than others.

Factors That Affect the Lifespan of a Helical Pier

● Raw materials used in helical pier manufacturing● Manufacturing processes and quality control● Skill and care of foundation installer/contractor● Soil type, composition, and characteristics● Climate and weather● Depth of frost line
The only way to account for these factors is to have a foundation expert assess your project and give you recommendations based on engineering principles and science. There’s simply no way that I could cover all the possibilities in a single blog post.
But, I’ll tell you what I can do for you in next few minutes.

By making a few assumptions about soil type and characteristics, we can estimate how many decades a helical pier might last (in our little thought experiment).

Believe me, you’ll be amazed at how long it can be.

How Soil Affects Your Foundation’s Lifespan

Earlier I said there’s many factors that determine how long a helical pier can last in the ground. What I didn’t tell you was that one of those factors plays a huge role in determining a helical pier’s longevity…

The soil.

Yep, the ground itself is the single most powerful factor when it comes to the lifespan of your foundation. In much of the continental United States, there’s a pretty good chance you’ll face (to some degree) expansive soils.

Expansive soils, like the name suggests, expand and contract (shrink and swell are the scientifically-correct terms) as the soil gets wet and dries out. This ‘shrink and swell’ activity causes several problems for foundations, one of the worst is destructive “uplift pressures” on the structure. 

The cracks we see in the soil here are indicative of expansive soil. As it dries, the soil shrinks and produces these cracks.

Expansive soils also tend to be poorly-draining soils owing to their clay content. When the ground gets saturated, like in spring melt or after a heavy rain, the moisture can linger and affect infrastructure in the ground.

Because helical piers are made from steel, we have an excellent understanding of how they’ll interact with the soil and degrade over time. But, you might be surprised to learn that corrosion isn’t the worst enemy of a helical pier. Yes, given enough time corrosion would eventually destroy a helical pier. But that doesn’t mean corrosion is the biggest concern.

In reality, most helical piers in commercial and industrial applications will use steel that’s thick enough for corrosion to barely even factor in as a design consideration. For the majority of your projects, corrosion won’t be a concern over the projected life of the structure.

However, I’d be remiss if I didn’t share some of the factors that can affect the rate of corrosion of your steel helical pier foundation. They’re helpful to know in order to develop a better understanding of how the soil affects your foundation.

Soil Factors That Influence the Corrosion of Steel

● Soil resistivity (how electrically conductive the soil is)● Acidity of the soil (expressed in pH)● Moisture content● Amount of dissolved salt● Combination and amount of mineral● Oxygen levels● Activity of organic matter like bacteria, fungus, etc

The chemical interactions that cause corrosion are complex and varied

A helical pier engineer will use a range of factors to calculate the usable lifespan of a helical pier. These factors are based on careful study of the soil at the project site and assessing it against established engineering principles.

In the rare occasion the soil is especially corrosive, such as landfills or industrial sites, designers can increase the helical pier’s corrosion protection. There’s a few ways to achieve it.

How to Protect a Helical Pier from Corrosion

● Increasing the thickness of steel used for the shaft and helices● Hot-dip galvanizing the pier to add corrosion resistance (though on commercial projects sacrificial thickness is more effective and economical)● Cathode systems that use DC current to slow or halt the corrosion process (generally used in abnormally corrosive soils)

A good geotechnical report on soil conditions is crucial to understanding how the helical pier will interact with its environment over time

The science behind protecting a helical pier is a topic all its own, and it’s not important to understand today. Remember, for the majority of projects helical pier corrosion will not be a major limiting factor. If you’re curious to learn more about corrosion and helical piers, feel free to click here and get in touch with our foundation experts.

Alright, that’s plenty of preamble. Time to uncover the answer to our question:

How long can a helical pier foundation last?

How Long Your Helical Pier Foundation Could Last

So, to recap, here’s the assumptions we’re making about the conditions our hypothetical helical pier will face:
● Installed in moderate/severe expansive soil, which is common across the U.S.● Soil has high clay content and is poorly draininh● The pH level of the soil is 7.0 (neutral pH)● Climate conditions are cold winters, wet springs, dry summer/late summer● Properly installed by skilled helical pier contractors
In those conditions, and remembering that many factors could affect this number, a reasonable estimate of the lifespan of a helical pier is…

Over 180 years.

Yep, that’s almost two centuries. In fact, to put it another way:

If you assume a new generation is born every 25 years, 180 years equals nearly eight generations of support. That means long after you’re gone, if the structure still stands, your far-flung descendants in the year 2202 could still see evidence of your project.

The Carysfort Reef lighthouse, pictured here in 1962, still stands today supported on wrought-iron “screw piles” (helical piers)

Take the Carysfort Reef lighthouse that stands in 4-1/2 feet of water a few miles east of Key Largo, Florida for example. It was constructed in 1852 on a foundation of wrought-iron “screw piles” (helical piers). Today, 170 years later, the lighthouse still stands on the Carysfort Reef. Through storms, swells, and salty seawater, the foundation has more than stood the test of time.

If a lighthouse built in 1852, on wrought-iron helical piers, in a tough marine environment, without modern engineering, can stand for 170 years then you can imagine how long high-quality steel helical piers will hold firm.

A really, really long time.

Conclusion

When you’re choosing a foundation for your project, the last thing you ever want to worry about is whether or not the foundation will last. Heck, if anything your foundation should be something you have the most confidence in. Your foundation is what supports all other aspects of your project.
Helical piers have more than enough durability to last for decades, even centuries, into the future. Even if you’re facing especially difficult conditions, a properly designed and installed helical pier foundation should support your project for countless decades.
Interested in a foundation that will outlive your great-great-grandkids? Our expert foundation consultants will help you identify the best solution for your project. 
Scroll down to get in touch and have a no-obligation chat about your project and how helical piers might be able to deliver better speed, economy, and durability.