Building components · Substructure & Ground
Pile Shaft
Explains the pile shaft as the load-carrying element itself, distinct from the piled foundation arrangement it belongs to.
Educational reference entry. What this element has to do, and whether any particular arrangement of it is adequate, depends on the whole assembly, the loading, the exposure, local requirements, the manufacturer's instructions and qualified professional design.
Overview
What a pile shaft is
A pile shaft is a slender element installed vertically into the ground to carry load past material that cannot support it. It works by bearing at its base, by friction along its length, or by both together.
It exists because the competent ground is not where the building is. Rather than excavating down to it, the shaft reaches it, and everything above is connected to the shaft rather than to the surface ground.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a pile cap. The cap is the element above that gathers load and delivers it into one or more shafts.
- It is not a foundation in the shallow sense, because it does not rely on the ground immediately under the building.
- It is not a column, although both are slender vertical members. A column is in air with known conditions along its length; a shaft is in ground whose conditions vary and were established by investigation.
Terminology
Common names and aliases
These names describe the same element. The library keeps one entry per component so that a trade term or a regional name never becomes a second, thinner page.
- pile
- pile shafts
- bearing pile
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- The ground profile it passes through and founds in, which is established by investigation rather than assumed.
- The installation method, since how a shaft is formed affects both the shaft and the ground around it.
- Verification during installation, because much of a pile is permanently unobservable once complete.
- How load is transferred into it at the top, which is the cap's job but is a property of the connection.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
Installation is where most of what can be known about a pile is established, because the shaft is inaccessible afterwards.
Installation records and any testing are the evidence of what was actually built, and they are worth asking for.
How a pile settles under load differs from how shallow foundations settle, which matters where the two are mixed on one site.
The ground environment along the shaft, including any aggressive conditions, is a design input rather than an afterthought.
Materials
Commonly formed from
Material families this element is commonly realised in. This states common practice only — it is not a statement that any of these materials suits this component in a particular building, which depends on the whole assembly and on qualified review.
Assemblies
Building systems this element is met in
The role this component fills inside each assembly. A role describes what the element does there — it is not a statement that this component suits that system in any particular building.
Where it is met
Application contexts
Building contexts where this element is commonly encountered. Association is not recommendation: appearing here does not mean the component suits every instance of that context, or any particular one.
- Substructure
Clarifications
Commonly misunderstood
- That every pile carries load at its base. Many carry a substantial part of it by friction along the shaft, and the mechanism affects behaviour.
- That piling removes ground risk. It changes which ground is being relied on, and that ground still has to be understood.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- What ground investigation supports the pile design, and what load-transfer mechanism is assumed?
- What installation records and testing will exist for these piles?
- How is load transferred from the structure above into the piles?
- Are there aggressive ground conditions along the shaft that affect durability?
Go deeper
Related Build Design Hub guides
Planning guidance behind the decisions this element involves.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this element comes up.
What this entry does not do
- No depth, diameter, capacity, spacing or testing regime is stated here.
- Piling is specialist geotechnical and structural work; nothing in this entry supports designing or assessing a pile.
Substructure & Ground Elements
The prepared surfaces, layers and buried members between undisturbed ground and the first structure above it.
Browse all substructure & ground entries →