Building components · Substructure & Ground
Ground Beam
Explains the ground beam as a spanning member within the substructure, distinct from both the foundations it spans between and the beams in the frame above.
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 ground beam is
A ground beam spans between discrete foundation points — pile caps, pads or piers — and collects the load of the wall or columns above, delivering it to those points rather than to the ground directly beneath it.
It appears wherever the ground immediately under a wall cannot be relied on but competent support exists at intervals. It changes the load path from continuous bearing to spanning, which is why it is a structural member rather than a foundation.
Boundaries
How it differs from nearby elements
The distinctions that keep this entry from being a restatement of its neighbours.
- It is not a strip foundation. A strip bears continuously on the ground beneath it; a ground beam deliberately spans past that ground to reach supports at intervals.
- It is not a pile cap. A cap sits over one pile group and transfers load into it; a beam spans between caps.
- It is not a beam in the frame above. The position is different, and so are the exposure, the ground contact and the durability considerations that follow.
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.
- ground beams
- capping beam
- tie beam at ground level
Dependencies
What it depends on
What has to be right elsewhere for this element to do its job.
- The foundation points it spans between and their spacing, which set what it has to span.
- Whether the ground beneath it is expected to touch it at all, since some designs deliberately keep it clear.
- Ground conditions that can change beneath it, including heave from soils that swell.
- Its connection to the elements it supports and to the supports it bears on.
Considerations
Topics that genuinely apply here
Subjects worth discussing about this element. These are discussion topics, never measured values, ratings or performance claims.
Ground beams frequently exist because the ground beneath is expected to move; how that movement is accommodated is a central part of their design.
A member at or below ground level is in a different exposure environment from the same member in a frame above.
Buried structural members are difficult to inspect later, which raises the value of getting protection right at construction.
Ground beams are cast or placed in ground conditions, and the working environment affects what is achievable.
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.
Materials
Commonly incorporates
Materials this element commonly contains as a distinct constituent part, rather than being made of.
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.
Junctions
Interfaces this element takes part in
Junctions where the condition between this element and another governs how the construction behaves. These name the junction and the subjects it raises; they are not details, arrangements or approved ways of building.
Ground Beam Bearing on a Cap
Where a spanning substructure beam delivers wall loads into the caps over pile groups.
Raises: Structural transfer · Buildability · Moisture · Movement
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
Related elements
Neighbouring components
Typed relationships to other elements. There is deliberately no generic “related” category: an edge that cannot be classified does not exist.
Clarifications
Commonly misunderstood
- That a ground beam bears on the ground under it. In many designs it deliberately does not, and assuming otherwise misreads the load path.
- That it is simply a deep strip foundation. The load path is different, which is the whole reason it exists.
Conversations
Questions for qualified professionals
Questions worth asking someone with the project in front of them. This page cannot answer them.
- What is the ground beam spanning between, and what does the design assume about the ground beneath it?
- Is any provision made for ground movement or heave under the beam?
- How does load from the wall above reach the beam, and from the beam reach its supports?
- What protection applies to a structural member at this level, and how would its condition be assessed later?
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 span, section, reinforcement, cover or load is stated here, and none can be inferred.
- Ground beam design is structural and geotechnical engineering work.
Substructure & Ground Elements
The prepared surfaces, layers and buried members between undisturbed ground and the first structure above it.
Browse all substructure & ground entries →