I-beam: sizes and weight per metre

The I-beam is the workhorse of floor structures. The number in the marking is the profile height in centimetres; the letters after it name the series.

Standard I-beam chart (B series)

B, Sh or K

• B — standard. The flange is narrower than the height. The classic floor beam and the lightest for a given depth.
• Sh — wide flange. The flange nearly matches the height. It carries more load and resists twisting better — the choice for spans over 6 metres.
• K — column. The flange equals the height and the profile is almost square. It works in compression, so it belongs in posts and columns, not beams.

A simple rule: lying horizontally, use B or Sh; standing vertically, use K.

Estimating beam depth

A rough engineering rule for floors: beam depth ≈ 1/20 of the span. For a 4-metre span that is 200 mm, i.e. 20B1. It is no substitute for a structural calculation, but it rules out the obviously wrong options and lets you cost the job early.

I-beams travel on 11.7–12 m long-load trailers. Such a vehicle may not fit a narrow street or a tight development — tell us about site restrictions when you place the order.

We stock these positions in Rolled metal.