A helical pier is a long, round steel shaft pipe with a single or multiple helix designed to be hydraulically driven into the earth to a desired depth determined by an engineer. A helical pier’s design is characterized by a single, double, or even triple flite (refer to image on the right) is driven into the soil using hydraulic torque to depths that can only be determined by a soil boring. Helical piers are used to support the structures load-bearing members where soil conditions are poor, making it difficult to set up for a traditional spread-footer foundation system. Helical piers are used in new construction and repairing existing
foundations that have problems with settlement or heaving (uplift from expansive clays). Helical piers are a good option for foundation systems where weak soils are present. These piers cause little disturbance to the soil and neighboring structures, and the loads of the structure are transferred to load-bearing soils deep in the earth.
When to Use Helical Piers
Helical piers are used for both residential and commercial applications. These piles are often referred to as caissons, mini piles or driven piles. Helical piers are commonly used when there is structural damage or when the structure has been built in unstable soil conditions and is experiencing differential settlement damage. You can identify foundation damage by the following signs:
- Cracking on the interior or exterior walls
- Floor sloop or uneven conditions
- Door and window start sticking
- Cracking in the ceilings
- Cracking in foundation walls
- Leaning chimneys
Types of Helical Piers
There are two types of helical piers and/or helical tye backs, round shafts and square shafts
Round shaft helical piers can handle vertical loads when high compression is suspected. Conventional designs include:
- Round-Shaft Helical Foundation Piers
Foundation Masters, LLC round-shaft helical foundation piers feature a steel tube shaft with a hollow circular pipe section. Round-shaft helical piers have a higher section modulus and can handle vertical loads when high compression is suspected, as well as a higher bending capacity. These foundation piers are most often applied in new construction along with foundation repair dealing with lighter loads as residential construction.
- Square-Shaft Helical Foundation Piers
Foundation Masters, LLC square-shaft helical tye backs feature a high-strength solid steel shaft that delivers a higher capacity-to-torque ratio. We’ve also found that they’re often easier to couple onto and install.
Because they’re not an efficient guard against buckling and have little to no lateral capacity, square-shaft helical tye backs should only be used in tye back situations such as retaining walls and other earth retention systems. Square shafts are suitable for areas where tension forces are suspected, and have a greater yield and tensile strength.