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Helical Foundation Systems

Helical foundation systems are also called helical piers or piles. This is a type of deep foundation system that stabilizes existing structures or can be installed before construction to ensure that the building will remain stable.

History of Helical Piers

The helical pier was invented by Alexander Mitchell, an Irish engineer, as a method to stabilize lighthouses and other structures that were built on mud and sand. Originally called a screw-pile, the piers were made of cast or wrought iron and were screwed into the ground. The design and installation method provided more stability in the mud and sand than straight piers.

The first helical foundation system was installed in the 1830s. And the first helical, or screw pile, installed in the US was at Brandywine Shoal, Delaware Bay. The lighthouse at Brandywine Shoal replaced a straight pier lighthouse which was destroyed by ice flows.

In addition to installing the new lighthouse on helical piles, the tops of the piles were interconnected. This created an ice breaker which would further protect the lighthouse from the heavy ice floes common during New England winters.

In the U.S. helical piles quickly caught on after the Civil War when the Lighthouse Board made the decision to replace the lighthouse vessels currently serving in interior waterways (bays, sounds and rivers) with screw pile lighthouses. Over 100 screw pile lighthouses were constructed to replace the older light vessels.

Many screw pile lighthouses have withstood the test of time. The Roanoke River Light, which was built in 1877, is the last screw pile lighthouse standing in North Carolina. And the Carysfort Reef Light, located four miles outside of Key Largo, FL and constructed in 1852, is the oldest screw pile lighthouse still in service in the United States.

How Helical Piers Work

Helical foundation systems are screwed into the ground - like a corkscrew - until it reaches stable soil. Once the helical pier is installed, a bracket is placed under the foundation footing. This bracket keeps the helical pier in place to ensure that the structure is supported by the pier. After the pier is installed it can even help lift the structure - which can restore the value of your home.

Another helical foundation system is a soil nail or helical anchor. Like the pier, the anchor screws into the ground. A bracket is placed on the interior wall and the anchor is drilled into the soil to stabilize and straighten the wall.

Helical anchors are used to stabilize bowed or cracked basement foundations. Even severely damaged walls can be safely repaired using helical anchors.

The Science Behind Helical Piering Systems

JES uses FSI helical foundation systems which have been extensively tested* in accordance with the International Code Council (ICC), which is the authority on design safety and standards. The piers are designed in accordance with the ICC-ES AC358 criteria for geometry of the helical blades.

This means that the helical foundation systems we use are safe, effective and built to last.

The helical blade is the portion of the pier that looks like the wings on a screw. These blades are spaced to ensure that the pier is strong and installs easily with minimal disruption to the surrounding soil.

Helical Pier Benefits

One of the many benefits of helical foundation systems is installation doesn't generate any spoils. This means that no digging is required so you don't have to worry about cleaning up piles of dirt and debris.

And unlike piles, helical piers don't create vibration during installation. Piles are typically driven into the ground which can damage surrounding structures and create additional liabilities.

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Footnotes:

* The ICC does not have standards for every foundation system currently available. FSI tests in accordance with ICC standards when available. If testing standards are not available, FSI conducts extensive internal tests with their team of Professional Engineers to ensure strength, accuracy, load bearing and safety meet or exceed other comparable ICC and industry standards.

References:

Wikipedia. Alexander Mitchell. Retrieved from http://en.wikipedia.org/wiki/Alexander_Mitchell_(engineer)

Wikipedia. Screwpiles. Retrieved from
http://en.wikipedia.org/wiki/Screwpiles