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Probably the single most commonly specified universal beam in UK domestic construction.

203 x 133 x 25 dimensions and weight

Approximate total weight by length — this is what determines how the beam is offloaded on site.

What is a 203 x 133 x 25 used for?

If one beam size defines British home alterations, it is the 203 x 133 x 25. It appears constantly in structural calculations for mid-size dormer projects, rear extension openings, wider knock-throughs and loft conversions, with published domestic tables showing it at around 4 metres under normal residential loading. The 133mm flange gives it considerably better lateral stability than the narrower 203 x 102 x 23, which is why engineers often prefer it even where the narrower section would work on paper. It is heavy enough at 25 kg per metre that a 4 metre length runs to roughly 100kg, so it is beyond comfortable manual handling and usually needs mechanical offload at the kerb. Its ubiquity is worth knowing about commercially too: because it is specified so often, it is one of the most readily available sizes and usually one of the most competitively priced.

Indicative span

Under typical UK domestic loading, published load tables place the 203 x 133 x 25 in the region of 3.8m to 4.5m. That assumes a simply supported beam with an evenly distributed load, an imposed load of around 1.5 kN/m² and a dead load of 0.5–0.8 kN/m².

Grades, lengths and finishes

The 203 x 133 x 25 is normally supplied to BS EN 10025-2 in S275JR or S355JR. S355 is the higher strength grade and is increasingly the default across the supply network; if your calculations specify one grade, tell us, because the two are not interchangeable. Mill certificates can be supplied with the order on request.

Beams are supplied cut to your lengths rather than as standard mill lengths, and we can arrange:

• Cutting to size — supplied ready to install, no cutting on site
• Drilling, notching and holes to your engineer’s details
• Welded cleats, end plates and connections
• Painting and priming, including intumescent coatings
• Galvanising for external or exposed applications

Delivery

A 6m length of 203 x 133 x 25 weighs approximately 150kg. That is beyond safe manual handling, so plan for mechanical offload and a clear route to the opening. We deliver direct to site across London, the South and the Midlands, with HIAB lorry crane offload available on request. If access is restricted — a terraced street, a rear garden, limited headroom — tell us at quote stage rather than on the day, and we’ll plan the delivery around it.

Other sizes in the range

Also searched as: 203x133x25, 203 x 133 x 25 UB, UB 203x133x25, 203×133 UB25, 203×133 RSJ. The term “RSJ” is still widely used for universal beams, though strictly it refers to the older rolled steel joist section with tapered flanges.

• All universal beam sizes
• Universal columns (UC) — where the load is vertical rather than spanning
• RSJ beams
• PFC parallel flange channels

Common questions

Dimensional data shown is nominal and for guidance. Span figures are indicative and must not be used in place of structural calculations.