How deep can you install screw piles?
Answer: As piles can be extended in 2m lengths, the theoretical depth of a screw pile is unlimited. For practical and economic reasons it is better to keep the total length less than 14 metres. Screw piles work in a slightly different way to other forms of piling and rely on end bearing on the helix plates only – skin friction is negligible. Concrete piles – because they depend on skin friction and end bearing – need to be quite deep (10-12 metres is typical). Screw piles generally need less length to achieve the same capacity, as the helix plates on a screw pile in practice act like a multiple set of end bearing piles all on a common shaft. Screw piles typically “torque out” (i.e. reach maximum capacity) at 6-8 metres.