How long can a supporting steel beam be?

How long can a supporting steel beam be

Supporting beams are an essential element when building a structure.

They are fundamental to a building’s stability, and it’s crucial that high-quality steel beams are selected to ensure the structural integrity of a building.

But how long can a supporting steel beam be?

Beams are horizontal elements used in construction to create a safe load path, transferring the weight to the foundations and into the ground.

In technical terms, a beam carries a load “perpendicular to their longitudinal direction”.

But how would you be expected to understand how long a supporting beam can be?

It requires a basic understanding of physics and engineering to figure this out, a job best suited to a structural engineer.

Their role is to calculate the load acting on a beam, understanding the force and stresses placed on it, and choosing the most appropriate material, size and shape for the job.

If we were to explain this in simple terms, to calculate the length a steel beam can span depends on:

  • the size of the beam
  • and the weight/force it needs to support

Steel beams used for support are also known as RSJ’s (Rolled Steel Joists), or you may have even heard of them being referred to as ‘I Beams’.

They are typically used in construction to build extensions and for the renovation of buildings to provide support when removing walls.

Although a DIYer can install an RSJ, it is best practice to have a structural engineer make the necessary calculations, as knowledge of building regulations is essential.

But to understand the process as best you can, it’s important to note that the larger the beam, the larger expanse it can span.

To speak with a member of our team for advice or support on your domestic construction project, please feel free to contact us today on 01384 389096 or email us at