This type of foundation repair is known as helical piers, helix pier, screw anchor or ground anchor and are similar to push piers.
They have steel tubing that is driven into the soil for support. The main difference is that they are screwed into the soil or twisted until they reach competent load-bearing soil or a particular torque pressure designed by the engineer. In the world of foundation repair they are used to support existing structures, patios and hillside support. In new construction they are driven into the soil and the new footing poured incasing the bracket for additional deeper support replacing the “old fashioned” concrete piers or deeper footings from years past.
The amount of torque required to install the helical pier is directly related to the capacity of the Helical Pier and design by the engineer. The helical pier consists of a steel shaft either round, pipe-style or solid, square shaft. Then plates (helix’s) are welded to the first driven section length. These plates that are welded to the tube increasing in size depending on the desired load needed for support. These plates allow the tube to be screwed into the soil while with each added depth; the system reaches greater resistance pressure.
Due to their design, the helical piers do not need to be installed as deep as the resistance piers since the helix on the system is what captures the tension or torque needed to support. They must only be installed below the active soil or weak layers. The project engineer determines the target depth or PSI needed to be reached. Helical piers do offer some lateral support which the push pier or resistance pier does not, but it also does not fully pull soil out of the equation since they are not driven to solid strata or bedrock.
Advantages:
- Very high capacities
- Installed quickly, sometimes in a day or two
- Soil removal from site is unnecessary
- Installs with little or no vibration
- Easily load tested to verify the capacity
- Minimal effects on landscaping
- Installs below unstable or sinking soil
- Great for use with light structures, patio’s,, room additions, pre-construction
