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Many Names, One Purpose
Helical piers are referred to by many names, including:
- Helical piles
- Helical anchors
- Screw piers
- Screw anchors
Despite different terminology, the same basic concept is used in all helical piers: torque. When your house’s foundation is settling, it needs maximum support with the most cleverly-engineered materials, installed correctly. Helical piers are designed to fit the bill by using torque to build up strength in order to transfer the weight of your home from a sinking foundation to their strong underpinning.
Construction of Helical Piers
High-strength steel “pipe” is welded together with helix-shaped disks towards the bottom of what’s usually referred to as a “lead”, creating what indeed looks like a “screw anchor”. To create more stability and strength, additional overall surface area spreads out the weight load, and the shape of the helix, much like a screw, creates torque as it’s driven into more stable soil than the topsoil holding up your foundation. If you’ve been to the beach and screwed in a base designed to hold your umbrella, you’ve seen this concept in action. However, with a house, you can’t go with cheap plastic that may break–you need steel!
Additional “extension” sections are crafted to connect to the lead section, adding additional vertical depth as much as may be necessary to reach adequate soil, where adequate torque and stability are achieved.
How Helical Piers are Installed
The installation process for helical piers on an existing foundation typically looks like this:
- Holes are dug down until the house’s foundation footer is exposed.
- Depending on the construction of your foundation, typically a section of the footer’s “spread” that extends past the wall outward is chipped away to maximize the efficacy of foundation brackets used in later steps of installation.
- The helical pier’s “lead” shaft is connected to a skid steer or similar machinery, fitted with an arm that uses hydraulic power to twist the anchor, screwing it into the soil.
- Additional extension sections are attached to the lead section as needed to drive the pier as deep as is necessary to achieve stability.
- Torque is monitored using gauges to ensure maximum strength and stability.
- Once maximum stability has been reached, the extension section is cut to the correct size, and high-strength steel foundation brackets are attached to the pier.
- Installation methods can vary, but typically lifting plates are connected to allow more fine-tuned adjustments.
- Jacks are used to create upward pressure, transferring the weight and load of of your home’s foundation to the steel piers wherever they’re installed.
- Once safe and sufficient pressure has been achieved to ensure stability, lifting plates and hardware are removed and final adjustments may be made.
- The holes are filled back in with the soil that was removed and tamped down as much as possible.
Additional steps may be necessary based on piers’ location, home construction, obstacles in the way, accessibility by machinery, and other factors.
Other Uses for Helical Piers
Because helical piers rely on torque rather than resistance to build up pressure and stability, they can be installed without the counterweight of a foundation wall needed by other types of piers. This means they can also be used in new-construction applications, where stability of the soil may be in doubt. Instead of the typical L-shaped brackets connected to the foundation in existing construction, a flat plate is installed. Concrete can be poured on top of these piers for immediate stability relying on the strength of the pier rather than weaker soil towards the surface. These are often referred to as “pre-construction helical piers”.
You can also read about our wall anchor system here, which uses the same concepts and the same helical piers, but installed differently and connected to a basement or retaining wall with different plates and methods.