My Beam Was Cut Too Short — Is That a Problem?

It depends on how short, and where. The critical issue is whether the beam has enough bearing length at its supports — that is, sufficient overlap with the padstone or post beneath it to transfer the end reaction into the support safely.

The Bearing Requirement

The PorthouseDean specification is clear: unless the drawings specifically note otherwise, beams must bear over the full width of any spreader or post.

This means if the padstone is 150 mm wide, the beam end must overlap the padstone by the full 150 mm — not sit on 80 mm of it because the beam was cut 70 mm short. The full bearing ensures the end reaction is spread across the design contact area and that the masonry and padstone compressive stresses stay within acceptable limits.

The Exception: Beams on Padstones Running Parallel

The rule is different when the padstone runs parallel to the beam (e.g. a padstone oriented so that its length runs in the same direction as the beam span). In this case, the shim detail applies — see the padstone notes and specifications for the correct arrangement when the beam is parallel to its supporting padstone.

What to Do if the Beam Is Too Short

If a beam has been cut on site and is now too short to achieve the required bearing:

1. Do not install it — installing a beam with inadequate bearing creates an immediate risk during construction and an ongoing structural deficiency
2. Contact PorthouseDean with the beam reference, the required span height and the bearing available — we can review whether the shortfall is within tolerance or whether the beam needs to be replaced
3. In some cases a bearing plate or additional padstone extension can be introduced to compensate — this requires engineering review

Replacing a fabricated steel beam is an expense, but it is far smaller than the consequences of a bearing failure during or after construction.

Preventing This Problem

Beam lengths should be established from the as-built architectural drawings and confirmed by site measurement before fabrication. Structural drawings are not fabrication drawings — final dimensions must be measured on site. See the related article on using structural drawings for fabrication dimensions for more on this.

Contact PorthouseDean if you have a beam length issue that needs reviewing.