A pile cap beam — Dutch “kesp” — is a short connecting beam of wood or concrete laid across the heads of two (or more) driven piles to tie them together. The whole of the beam with the piles beneath it is called a pile bent. The beam spreads the load of the masonry or the longitudinal timber over the piles and bridges small height differences between the pile heads.
How it works
- The beam is laid across two piles driven side by side (the classic Amsterdam method)
- On top of it comes the longitudinal timber and then the masonry or wall
- Because the beam thickness can vary, the pile heads do not have to stand at exactly the same height
- In the Rotterdam method with a single pile, the beam sits directly on the pile head
Application
- Traditional timber pile foundations under older buildings in low-lying, wet areas
- Recognisable during foundation repair and soil investigation of monuments and canal houses
Points to note
- The beam, pile head and longitudinal timber must stay permanently below the lowest groundwater level; if they dry out, wood rot (pile rot) and settlement follow
- A falling groundwater level is the main cause of foundation problems with this type
- During repair, the switch is often made to concrete or steel structures
Related terms
- Driven pile
- Amsterdam method
- Bearing capacity of a pile
- Foundation
- Foundation repair
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