CFA (Continuous Flight Auger) piling is a process of pile foundation formation whereby builders drill a shaft into the ground and pump concrete through the hollow core of the drill as it retracts. Michael Zeman describes it as "the most common drilling method in the UK for small to medium diameter shafts."
Whereas other piling methods will drill a hole, remove the drill bit and then fill the hole with concrete, CFA piling immediately fills the drilled shaft with concrete. This reduces the risk of the sides of the shafts collapsing, eliminates free water in the bottom of the shaft, and lets the engineer and contractor know exactly how deep the concrete goes (and therefore assures them that the foundation strength will support the structure).
In comparison to other piling methods, that involve either hammering a steel bore into the ground or using vibrations to dig into the soil, CFA piling requires minimal vibration and remains relatively silent. This minimises any risk of damage to nearby buildings, and the lack of excessive noise will keep residents in the area happy.
Range of Sizes
CFA piling can be drilled in a range of shaft diameters, from 10 to 60 inches. This makes it very versatile, capable of accommodating the foundation requirements of many size buildings. This, coupled with the fact that it is quick to install, means that building foundations can be completed in a relatively short time, saving costs on build duration.