In general bored piles offer the most economical foundation as they can be constructed in a wide choice of diameters, typically ranging from 300mm to 1800mm, and to depths of up to 70m at rakes of up to 1:4. They can thus be tailored precisely to the particular requirements of the building or excavation. This flexibility means that bored piles can provide solid foundation elements suitable for almost all site conditions.
Bored piles can be classified into two main groups, according to their load bearing behavior: friction piles, which transfer loads mainly by frictional resistance along the shaft; and end bearing piles in which load is primarily transferred to the surrounding soil of through the pile base.
Depending on the structural requirements, bored piles may be constructed singly, in groups or as walls using secant, contiguous or king piles, with or without infill.