Helical piers have a screw-shaped plate welded to a zinc-coated steel shaft, and are made in different sizes for different soils and applications.
As the driver turns the pile, it simply screws into the ground until the installer is confident it’s below the frostline and in soil with sufficient bearing capacity.
Several types of caps are available to attach piers to framing; some are adjustable in order to fine-tune the elevation.
A pier’s bearing capacity usually relates to the torque required to drive it. A gauge on the machine measures the hydraulic pressure, which correlates to the torque.
Shaft extensions are welded on and the pier driven as deep as needed to reach soil with adequate bearing capacity.
The pier can be steered around a below-grade rock by moving the driver’s boom; once the obstruction is passed, the boom pulls the shaft plumb again.
ven though this pier penetrates about 13 feet into the ground, there’s no pile of excavated soil as there would be with a conventional footing.
A typical helical pier foundation has greater bearing capacity than one with concrete piers, and installs with little disturbance to the landscape.
Adding a vertical extension to the drilling rig makes it possible to drive piers into steeply sloped sites.
The machine is also well-suited to foundation stabilization work, as it can fit in tight spaces around existing homes.