What is the Difference between End-bearing Piles and Friction Piles in Commercial Design?

In commercial pile foundation design, the primary difference between end-bearing piles and friction piles lies in how they transfer structural loads to the subsurface soil. The choice between them depends on the site’s soil stratigraphy and the depth of competent soil layers.

### End-Bearing Piles

End-bearing piles function by transferring the structural load directly to a strong, incompressible bearing stratum, such as bedrock or dense sand.

• Load Transfer: Pressure is concentrated at the tip of the pile.
• Typical Soil Conditions: These are used when a hard, competent layer exists at an achievable depth.
• Settlement: They typically experience minimal settlement because the bearing layer is incompressible.
• Capacity Determination: Capacity is primarily determined by end-bearing resistance.

### Friction Piles

Friction piles transfer structural loads to the surrounding soil through skin friction along the length of the pile shaft.

• Load Transfer: The load is distributed through the interface between the pile surface and the soil.
• Typical Soil Conditions: These are favored in locations with deep deposits of clay, silt, or loose sand where no hard bearing layer is reachable.
• Settlement: They generally exhibit greater elastic shortening and require more rigorous deep foundation settlement analysis.
• Capacity Determination: Capacity is determined by shaft resistance and installation torque correlation.