Universal Beam (UB) vs Universal Column (UC): What UK Builders Actually Specify
In the UK, the term “RSJ” is still widely used on site, but in most modern projects it refers to either a Universal Beam (UB) or a Universal Column (UC). While they look similar, these sections have different proportions and are specified for different structural roles.
Understanding the difference helps avoid ordering the wrong section and prevents delays when steelwork is being supplied.
For general availability across both section types, see:
What Is a Universal Beam (UB)?
A Universal Beam (UB) is a rolled steel I-section that is deeper than it is wide. This shape means it is commonly specified where the steel member is primarily working in bending rather than compression.
Typical applications include:
Horizontal support for internal load-bearing walls
Floor support members and joists
Structural lintels for extensions and refurbishments
Steel members spanning between supports, subject to structural design
Although many builders still refer to these as “RSJs”, the correct supply term is Universal Beam.
👉 Explore Universal Beams (UB)
What Is a Universal Column (UC)?
A Universal Column (UC) is also a rolled steel I-section, but its depth and flange width are much closer in proportion, giving it a more square appearance compared with a UB.
Universal columns are commonly specified for:
Vertical load paths
Steel columns and posts
Applications dominated by compressive forces
Situations where stability in both axes is typically specified
Despite the name, a UC is defined by its geometry rather than the orientation in which it is installed.
👉 Explore Universal Columns (UC)
Universal Beam vs Universal Column: Key Differences
| Feature | Universal Beam (UB) | Universal Column (UC) |
|---|---|---|
| Section proportions | Deeper than wide | Near square |
| Typical orientation | Horizontal members | Vertical or multi-directional |
| Common site term | Often called RSJ | Often called RSJ |
| Visual appearance | Taller web, narrower flange | Wider flange, shorter web |
| Specification basis | Structural engineer | Structural engineer |
All dimensions are nominal and subject to standard mill tolerances.
Why UBs and UCs Are Commonly Mixed Up
On UK building sites, “RSJ” is often used as a catch-all term for structural steel. This frequently leads to:
Universal columns being requested when a universal beam is shown on drawings
Orders being placed based on names rather than section proportions
Incorrect price comparisons between different section types
In practice, the structural engineer’s drawings or beam schedule will clearly state whether a UB or UC is required, along with the nominal size and steel grade.
Practical Ordering Considerations
Before ordering steelwork, it is common to confirm:
Whether the section is specified as a UB or UC
The nominal depth × width shown on drawings
The steel grade noted by the engineer
The required finish, such as mill finish or red oxide primer
Delivery length and any cutting requirements
Clear terminology at enquiry stage helps suppliers quote accurately and reduces unnecessary revisions.
Finishes and Supply
Both universal beams and universal columns are commonly supplied as:
Mill finish steel, supplied as-rolled with no coating
Red oxide primer, applied as a temporary shop primer for handling and storage
Final corrosion protection depends on the project specification and site conditions.
👉 View Mill Finish RSJs
👉 View Red Oxide RSJs
Frequently Asked Questions
Is a Universal Beam the same as an RSJ?
RSJ is a legacy term. In modern UK construction, it typically refers to either a universal beam or a universal column.
Can a Universal Column be installed horizontally?
A UC can be installed in different orientations if specified by a structural engineer. The name does not restrict orientation.
How do I know which section is required?
The structural engineer’s drawings or beam schedule will specify whether a UB or UC is required.
Are UBs and UCs interchangeable?
No. Even where dimensions appear similar, section properties differ and substitutions should not be made without approval.
Structural Disclaimer
Universal beams and universal columns should be specified by a qualified structural engineer. Installation and use are subject to approved designs and building control approval. This article is provided for general guidance only.