RSJ, UB, UC and PFC are British steel section names. An RSJ (rolled steel joist) is an older tapered-flange I-beam, though the term is now used loosely in the UK for almost any steel beam. A UB (universal beam) is the standard British I-beam, a UC (universal column) is the British H-section for columns, and a PFC (parallel flange channel) is the British channel. In Canada the equivalent sections are the W-shape (for UB and UC) and the C or MC channel (for PFC), named in a different way and drawn from a different size range.
If you trained in the UK or are reading a UK-style drawing, this guide translates the terms and shows how close the sizes really are.
The translation table
| UK term | What it means | Nearest Canadian term | Canadian example |
|---|---|---|---|
| RSJ | Rolled steel joist; loosely "a steel beam" | W-beam (or S-shape for a true tapered-flange joist) | W200x27 |
| UB | Universal beam (I-section, deeper than wide) | W-shape, narrower-flange sizes | W310x39 |
| UC | Universal column (H-section, about square) | W-shape, wide-flange "column" sizes | W200x46 |
| PFC | Parallel flange channel | C-channel or MC-channel | C200x21 |
| UBP | Universal bearing pile | HP-shape | HP310x79 |
| SHS / RHS / CHS | Square, rectangular, circular hollow section | HSS (square, rectangular, round) | HSS 102x102x6.4 |
| Equal / unequal angle | Angle | L (angle) | L102x102x9.5 |
| Tee split from UB/UC | Tee | WT | WT cut from a W |
| Padstone | Bearing block under a beam end | Bearing plate, pedestal or masonry bearing | Steel bearing plate on block |
| Building Control | Approval and inspections | Building permit and municipal inspections | City building department |
The words differ, but the jobs are the same: a beam carrying a floor, a column carrying a beam, a channel for framing or ledgers.
How UK and Canadian sizes are named
UK sections are named by serial size and mass per metre. The serial size is the nominal depth and flange width in millimetres, so a 203 x 133 x 25 UB is a universal beam about 203 mm deep, about 133 mm wide, weighing about 25 kg/m. Today the UK dimensions are set out in BS EN 10365.
Canadian W-shapes are named by nominal depth and mass per metre only, so a W200x27 is about 200 mm deep (actually 207 mm) and weighs about 27 kg/m. The flange width is not in the name; you look it up in the section table. Canadian sizes are the metric versions of the North American (imperial) series: a W200x27 is the same rolled section as an American W8x18. Our guide on how to read steel beam sizes explains the metric and imperial names.
So when you see "203 x 133" on a UK drawing, don't look for a W203 in Canada. Look for the W200 group, then compare the actual dimensions.
UB vs Canadian W-beams
Universal beams and W-beams come from different size series, but several sizes land very close. Dimensions below are from the UK Blue Book (BS EN 10365 sections) and published Canadian W-shape tables.
| UK section | Depth x width (mm) | Web / flange (mm) | Mass (kg/m) | Nearest Canadian W | Depth x width (mm) | Web / flange (mm) | Mass (kg/m) |
|---|---|---|---|---|---|---|---|
| 203 x 133 x 25 UB | 203.2 x 133.2 | 5.7 / 7.8 | 25.1 | W200x27 | 207 x 133 | 5.8 / 8.4 | 26.6 |
| 254 x 146 x 31 UB | 251.4 x 146.1 | 6.0 / 8.6 | 31.1 | W250x33 | 258 x 146 | 6.1 / 9.1 | 32.9 |
| 305 x 165 x 40 UB | 303.4 x 165.0 | 6.0 / 10.2 | 40.3 | W310x39 | 310 x 165 | 5.8 / 9.7 | 38.8 |
| 356 x 171 x 45 UB | 351.4 x 171.1 | 7.0 / 9.7 | 45.0 | W360x45 | 352 x 171 | 6.9 / 9.8 | 44.8 |
| 406 x 178 x 60 UB | 406.4 x 177.9 | 7.9 / 12.8 | 60.1 | W410x60 | 407 x 178 | 7.7 / 12.8 | 59.7 |
| 457 x 191 x 74 UB | 457.0 x 190.4 | 9.0 / 14.5 | 74.3 | W460x74 | 457 x 190 | 9.0 / 14.5 | 74.4 |
Some pairs are practically the same section; others are close but not identical. The small differences in depth, flange thickness and mass change the section properties, so a nearest match is a starting point for the engineer, not an automatic swap.
UC vs Canadian W "column" sections
Universal columns line up even more closely with the square W-shapes used for columns in Canada:
| UK section | Depth x width (mm) | Web / flange (mm) | Mass (kg/m) | Nearest Canadian W | Depth x width (mm) | Web / flange (mm) | Mass (kg/m) |
|---|---|---|---|---|---|---|---|
| 152 x 152 x 23 UC | 152.4 x 152.2 | 5.8 / 6.8 | 23.0 | W150x22 | 152 x 152 | 5.8 / 6.6 | 22.5 |
| 152 x 152 x 30 UC | 157.6 x 152.9 | 6.5 / 9.4 | 30.0 | W150x30 | 157 x 153 | 6.6 / 9.3 | 29.8 |
| 203 x 203 x 46 UC | 203.2 x 203.6 | 7.2 / 11.0 | 46.1 | W200x46 | 203 x 203 | 7.2 / 11.0 | 46.2 |
| 203 x 203 x 60 UC | 209.6 x 205.8 | 9.4 / 14.2 | 60.0 | W200x59 | 210 x 205 | 9.1 / 14.2 | 59.3 |
In Canada there is no separate "column" family. The squarer W-shapes in each depth group do the job, and they are used as beams too, for example where headroom is tight.
What is an RSJ, really?
RSJ stands for rolled steel joist. Historically it was a British I-section with tapered flanges: thicker at the web, thinner at the tips, much like the American S-shape. Tapered flanges need tapered washers for bolting and are less efficient than parallel flanges, which is why universal beams replaced them for most work.
In everyday UK use, though, "RSJ" now just means a steel beam in a house, usually a universal beam over a knocked-through wall. A UK builder asking for "an RSJ" for a wall removal is asking for what a Canadian would call a W-beam, or a "steel I-beam". The Canadian process is similar: a designer or engineer sizes the beam, a building permit is needed, and the beam is supported on posts down to footings. See our post on I-beam vs W-beam vs H-beam for the Canadian names.
PFC vs Canadian C-channels
A parallel flange channel has flanges of constant thickness. Canada's standard C-channels have tapered inside flange faces, and the miscellaneous MC series covers other proportions. The two families have different proportions too. For example:
- PFC 200 x 90 x 30: 200 mm deep, 90 mm flange, 29.7 kg/m.
- Canadian C200x28: 203 mm deep, about 64 mm flange, 27.9 kg/m.
Similar depth and mass, but the PFC's flange is much wider, so its properties, especially about the weak axis, are quite different. A PFC on a UK drawing has no automatic Canadian equivalent; the engineer picks a C or MC section and rechecks it. Our C-channel size chart lists the Canadian channels.
Grades and substitutions
UK drawings specify European grades such as S275 and S355. Canadian structural steel is specified to CSA G40.21 (for example 350W) or ASTM grades such as A992 for W-shapes. The numbers look similar, but the standards, test requirements and design rules differ, so the grades are not automatically interchangeable.
When a UK-designed project is built in Ontario, or a newcomer is working from habit:
- Use Canadian designations on the drawings. Fabricators and suppliers here stock and price W, C, HSS and L sections.
- Have the engineer of record approve every substitution of a UK section for a Canadian one, with the properties of both.
- Remember the code changes too. In Ontario, steel design follows the Ontario Building Code and CSA S16, not the Eurocode and its UK annex, so a UK calculation does not carry over as-is.
Canadian sections, cut and fabricated
We supply and fabricate W-beams, columns, channels, HSS and angles to Canadian designations, cut, drilled and welded to the shop drawings we prepare in-house. If your drawings use UK terms, send them over and we will flag what needs your engineer's sign-off. Request a quote, or see our steel products.
Frequently asked questions
What is an RSJ steel beam?
RSJ stands for rolled steel joist. Strictly it was an older British I-section with tapered flanges, but in the UK it is now used loosely for almost any steel beam in a house. In Canada the same job is done by a wide-flange W-beam, such as a W200x27.
What does UB mean on a steel beam?
UB means universal beam, the standard British I-section beam, deeper than it is wide. It is named by depth x width x mass, for example 203 x 133 x 25 UB. The Canadian equivalent family is the W-shape, named by depth and mass, for example W200x27.
What is a UC steel section?
UC means universal column, a British H-section with flange width close to its depth, made for columns. The Canadian equivalent is a squarer W-shape such as W200x46 or W150x30, several of which have nearly the same dimensions as UK UC sizes.
What is a PFC steel beam?
PFC means parallel flange channel, the standard British channel with flanges of constant thickness. Canada's standard C-channels have tapered inside flange faces, so a PFC and a Canadian C of similar depth are not interchangeable without an engineer's check.
