Over the past few years there has been a sharp increase in the number of construction projects utilizing screw pile systems in foundation designs.
Screw piles are steel piling and ground anchoring systems that come in several forms. They are commonly referred to as screw-piles, also referred to as screw piers, screw anchors, screw foundations, ground screws, helical piles, helical piers, or helical anchors. More recently, composite technologies have been developed for use in small screw piles.
Traditional foundation construction can involve large volumes of ground displacement to create building platforms and excavate for footings with the need to remove excess spoil from site. Screw piles offer an alternative as they are wound into the ground much like a screw fastening into wood, with minimal ground displacement. They can be installed quickly and efficiently using earthmoving equipment with hydraulic rotary drive attachments allowing noise and vibration disruption to be minimised. Screw piles can provide effective in-ground performance in a range of soil types, including earthquake zones where screw piles can be founded below soils prone to liquefaction.
Their first use dates to the 1800s when used as pile foundations for lighthouses, constructed from cast or wrought iron and with limited bearing and tension capacities when compared with modern technologies.
Screw pile installations have become increasingly popular in residential applications, incorporated into the construction of decks, sheds, cement pads, preformed stairs and swimming/ spa pool platforms. They are also used in foundation strengthening/ stabilisation and in particular seismic remediation works. Screw piles are also efficient when used on sites with difficult terrain.
The potential benefits of screw piles include:
- shorter project times
- less risk of weather delays
- ease of access
- ease of installation
- reduced health and safety risks to the workforce
- less soil displacement and spoil removal from site,
- reduction to the projects carbon footprint
- ease of removal when the foundations are no longer required
Masterspec have published a generic screw pile section (2314 Steel Screw Piles) available in Standard, Structural & Civil, Basic and Landscape. The section can be used as a template to accommodate specialist screw pile suppliers/ installers active in the NZ market or for bespoke designs.