By QED Consulting Engineers — structural & civil engineers, Notting Hill, Melbourne
When you remove a wall or span an opening, a beam carries the load that used to sit on the wall. Whether it's steel or timber, that beam has to be sized by a structural engineer for the exact span and load — it can't be reliably guessed. Here's how beams work and how engineers choose between steel and timber.
What does a beam do?
A beam bridges an opening and transfers the load above it — the floor, wall or roof — across to supports at each end. Get the beam right and the structure above is fully supported; get it wrong and you risk sagging, cracking or worse. That's why beam design is engineering, not a rule of thumb.
Steel vs timber beams
Both are widely used, and the choice depends on the situation:
- Steel beams (such as universal beams) offer high strength in a relatively small size, making them ideal for long spans or heavy loads — common when opening up living areas.
- Timber beams, including engineered timber like LVL, suit many residential situations and can be easier to handle and integrate with timber framing.
The engineer weighs span, load, available depth, and how the beam connects to the rest of the structure.
What determines the beam size?
The key factors are the span (how far it has to reach), the load above it, and the acceptable deflection (how much it's allowed to flex). The supports matter too — what sits beneath each end, and the footings below, have to carry the concentrated load. Our residential structural engineering team calculates all of this and specifies the beam and its supports.
Why an engineer must design it
An undersized beam is unsafe; an oversized one is unnecessary cost and can be hard to fit. The engineer designs the right beam for your opening and provides the documentation your building surveyor needs.
Opening up a space in your home? Talk to a Melbourne structural engineer for the right beam design.
Frequently asked questions
Steel or timber beam — which is better? Neither universally. Steel suits long spans and heavy loads in a compact size; timber (including LVL) suits many residential situations and integrates well with timber framing. The engineer chooses based on span, load and fit.
What size beam do I need to remove a wall? That depends on the span and the load above, which a structural engineer calculates. It shouldn't be estimated.
How far can a steel beam span? Steel can span considerable distances thanks to its strength-to-weight, but the exact size depends on the load and allowable deflection — the engineer works this out.
Who calculates the beam size? A structural engineer, who also designs the supports and footings the beam bears onto.
