Clearance to the Underside of Steel Beams at Wall Intersections

The PorthouseDean specification for steel installations states: ensure clearance is provided to the underside of steelwork at intersecting wall locations where no bearing information is shown, so as to prevent unintended load transfer to non-load-bearing walls.

This sounds technical — but the practical issue it addresses is simple and common.

The Problem: Beams Resting on Walls They Are Not Designed to Load

When a steel beam is installed and there happens to be a wall running beneath it that is not a designed support point, any direct contact between the beam soffit and the top of that wall will transfer load into the wall.

If that wall is a non-load-bearing partition — not designed to carry any vertical load — this creates an unexpected and unintended loading condition. Over time, the wall may crack, the floor above may redistribute loads in ways that were not calculated, and the structural behaviour of the building diverges from the design.

How to Achieve the Clearance

Where the structural drawings do not show a beam bearing at a particular wall, the beam should pass over that wall with a small gap between the beam soffit and the top of the wall. Even 10–20 mm of clear space is sufficient to prevent accidental load transfer.

In loft conversions, this is particularly relevant: the specification notes that there should be a 25 mm gap between the top of the existing ceiling joist and the underside of the steel beam to avoid unintended load transfer to the ceiling joists.

When to Raise it With the Engineer

If on site there is a wall that needs to be continuous through the floor zone but the beam cannot pass over it at the right level, contact PorthouseDean before proceeding. Forcing a beam onto an unintended support changes the load distribution and could invalidate the calculations.

Contact PorthouseDean with your site query and we will advise on the correct approach.