If you have problems with your foundation or you have soil issues that make building foundation a challenge, you may have heard your contractors talk about helical piers. These are steel pins with grooves like a screw. The name “helical” comes from the twist helix shapes that help the pier stay in place in shifting soil.
Contractors will use a hydraulic system to place the piers below the frost line to secure your foundation. When soil conditions present challenges to foundation contractors, they often turn to helical piers when typical footings and foundations would not work. The benefit of a helical pier is that the hydraulic digging is significantly less expensive than using an excavator to dig a deeper foundation.
Helical piers are also helpful when previously poured foundations begin to crack or weaken. Once a home or building is atop a foundation, repairs become difficult. The helical pier can take on the weight that is causing problems in the existing foundation. They prevent the need for contractors to lift the home off of the foundation for major repairs.
What Helical Piers Are Made Of?
Helical piers are made of steel. They can have a solid steel shaft, or they can have open shafts. Some have a combination of solid and open shafts. Manufacturers weld the helical plates to the shaft near the base of the pipe. As the piers are put into the ground, much in the same way a screw is put into the wood, the helical plate pulls the shaft into the ground. Usually, the helical pier has a three-inch pitch, and they are screwed into the ground, rather than augered into it.
Sometimes, helical piers are bolted together to meet the necessary depths. Contractors and engineers will decide on how many piers are needed to address soil density. The engineers will determine the distance that they need to be spaced to support the foundation and the building atop it. Each helical pier serves as a load-bearing element; even if they are bolted together, they still act individually.
Types of Helical Piers
Helical piers are available with either a round or square shaft made of galvanized steel. The round shafts are helpful in areas where foundations have issues with compression. The round shape can support compression forces and they can help buildings maintain their lateral stability. The round shafts are less likely to twist when compared to the square shafts. The square shafts are designed to manage tension forces because they have a higher tensile strength and yield than the round designs.
The round shafts are usually hollos and can measure between 2 ⅞” to 12 ¾” in diameter. The helices are tapered on a round shaft pier. The square piers have a solid shaft with a diameter that measures between 1 ¼” to 2”. They also have tapered helices, but they usually have a thicker range than those used on round shafts. Round shafts usually have a 3” pitch, but can have pitches up to 6”. The square shafts can have pitches as small as ⅜” and can have diameters up to 48”.
Why Use a Helical Pier?
Contractors use helical piles in all types of construction. Sometimes they are put into cassions or piles when soil is unstable or when the building site is prone to moisture from high water. They are also used when foundations become damaged. They can also be used when vibrations need to be dampened, which is why they are sometimes used to secure bridge foundations, too.
If you have a building or home that has foundational issues, you will see specific problems. When your foundation shifts or becomes damaged, your floor will become uneven. Windows and doors will not close properly, or they will close with gaps. You will see nails in the ceilings and your walls will show cracks - especially if they are made of plaster. Basement walls will also have cracks, and you might notice your chimney starting to lean. If you see any of these issues, you should contact a foundation contractor to evaluate the problem, and determine if you need repairs with or without helical piers.
Businesses that experience foundational problems or issues with their industrial floors often rely on helical piers for repairs. The process of installing helical piers is quite fast, so businesses do not need to shut down for long.
How Contractors Use Helical Piers
Before helical piers are installed, contractors and engineers will decide on how many are needed. They also determine how far apart they need to be installed, to manage the weight of the structure in the soil conditions. Contractors usually place them at a minimum depth of 10 feet, but they can be placed up to 30 feet below ground level. Occasionally, they are installed even deeper based on weight and soil conditions. A typical helical pier can manage the weight of a ten-story building.
If a helical pier is used to repair a pre-existing foundation, they are installed near the foundation and connected to it with brackets. Again, an engineer will determine the best locations for placement.
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