Steel beam is a broad description of a structural member. RSJ is used in everyday building enquiries for a rolled steel joist or, more loosely, a modern steel beam. Neither phrase on its own is an order specification.
Translate the conversation into a schedule
A usable schedule identifies the section family, full size, grade, quantity, cut length and fabrication detail. It should refer to the drawing revision that establishes supports and connections. Ask the engineer or fabricator to resolve ambiguous terminology before accepting a quote.
For a modern UB, use British Steel UB datasheet to check actual dimensions and tabulated mass. The shared RSJ.info table explains the distinction between nominal designation and actual properties. Existing historic members may require identification and assessment outside this dataset.
Separate three decisions
The engineer specifies a suitable structural arrangement. The fabricator prices and manufactures a defined item. The installer works to the issued design and construction plan. A casual label such as RSJ should not silently transfer a design decision to the person ordering steel.
The online calculators illustrate selected arithmetic models. They do not identify unknown members, determine a complete design or approve replacements. Keep the design, quotation and delivery information consistent through each revision.
Structural work must be designed by a chartered structural engineer and receive the applicable Building Control approval. This article is educational and has not received an independent engineering review.