Ask for an “RSJ” and most people on site will know you mean a steel beam. But on your engineer’s calculations you’re more likely to see something like “UB”. Here’s what the names mean when you’re ordering steel.
What does RSJ mean?
RSJ stands for rolled steel joist. It’s a name that has stuck around for decades, and builders and homeowners still use it to mean almost any steel beam.
What is a universal beam (UB)?
A universal beam, or UB, is the type of steel beam most often specified for homes, extensions and knock-throughs today. You’ll see it written on calculations with its size, for example 203 x 133 x 30 UB. You can see the full range we stock on our universal beams page.
What should I ask for?
The name matters much less than the exact size your structural engineer has specified. When you order, give us:
- The full section size and type, exactly as written on your calculations.
- The length of each beam and how many you need.
- Any cutting, drilling or fabrication shown on the drawings.
- The finish: raw, primed or galvanised.
If your paperwork says RSJ and you’re unsure what to order, send it to us and we’ll check it with you. If something doesn’t look right, we’ll suggest you confirm with your engineer before ordering.
Beams and columns
You may also see “UC” on your calculations. That’s a universal column, a different shape of section. Our guide on UB vs UC explains the difference.
Ordering an RSJ? Just give us the universal beam size from your calcs. Upload your drawings or call 0151 733 4927 for a quote.