Limitations of Square Shaft Helical Piles

Solid Square shaft helical piles have been used for decades in tension (pull) applications where loads tended to be light to moderate. Typically called helical tiebacks and soil nails, installation sometimes required heavy and cumbersome equipment. Material and fabrication for pile connection were typically less expensive than for round shaft piles.

About 30 to 40 years ago, contractors and manufacturers began promoting the use of square bar products for vertical applications where they are not as well suited; i.e., to resist compression (vertical) loads on new construction and retrofit piering projects.

There are two reasons for this:

1. The coupling of pile sections is stronger in round form than in square form.
2. Added load capacity is gained by the greater exterior surface exposure of the round pile (versus uneven exposure of square shaft) to the soil.

In short, hollow round shaft helical piles are better suited for torque (rotational drive pressure) and to resist compression loads than square shafts.

Tar Heel Basement Systems recommends using the round shaft helical piles to better suit compression applications. The round helical piers are mechanically screwed into the soil to the engineered designed depths and capacities to prevent further settlement and to permanently stabilize your home’s foundation, providing an opportunity to lift your home back to level without the expense and disruption of a full foundation replacement.