Screw piles

Screw piles, sometimes referred to as screw-piles, screw piers, screw anchors, screw it foundations, ground screws, helical piles, helical piers, or helical anchors are a steel screw-in piling and ground anchoring system used for building deepfoundations. Screw piles are typically manufactured from high-strength steel using varying sizes of tubular hollow sections with welded-on helical plates known as "flights".

The pile shaft transfers a structure's load into the pile, and is designed to meet both the application parameters and applicable building codes. The number of flights, their diameters, thicknesses, and position on the pile shaft, are all determined by a combination of:

1. The combined structure design load requirement
2. The geotechnical parameters
3. Environmental corrosion parameters
4. The minimum design life of the structure being supported or restrained.

Flights can be press-formed to a specified pitch or simply consist of flat plates welded at a specified pitch to the pile's shaft.

Although often used interchangeably, the terms helical anchors, helical piles and helical piers are not synonymous: Helical anchors consist of an extendable steel shaft with helical bearing plates. Piles or piers refer to strong base elements that withstand or transfer vertical/horizontal loads. Anchors are piles utilised only in tension, like restraining wall tiebacks or vertical ground anchors made to resist lateral forces (as on communications towers).