How Do I Support Brickwork Under a Steel Beam? (B3 Detail Options)

When a steel beam sits within a cavity wall — typically where an opening is formed in an external wall — the brickwork in the outer leaf of the cavity needs to be supported at the beam ends. Two standard methods are used.

Why the Brickwork at the Bearing Needs Support

A steel beam carrying a cavity wall above it sits centrally on its padstone, usually within the inner leaf. The outer leaf of the cavity must also be supported at the opening. Without a detail to carry the outer leaf at the bearing, the brickwork overhangs and relies on the masonry bonding alone, which is not adequate for Building Regulations.

Option 1: Welded Steel Plate (Shelf Plate)

A mild steel plate is welded to the underside of the beam flange and projects outward to provide a bearing surface for the outer leaf brickwork. The plate runs the full length of the beam including the bearings and is grouted into the masonry bed joints at each end.

This is a clean and reliable solution for external cavity wall lintels. The plate transfers the weight of the outer leaf masonry (and anything above it) into the beam.

Typical weld specification: 100 mm long × 6 mm hit-and-miss fillet welds at regular intervals along the plate length.

Option 2: Clip-On Angle

Where welding is not preferred (either for practical reasons on site or because the beam has already been installed), a clip-on angle can be bolted or welded to the beam bottom flange after installation. The angle projects outward to provide the same shelf function as the welded plate.

This is sometimes used retrospectively when a plate was not included in the original fabrication and the issue only becomes apparent on site.

Which to Choose?

Your preference, your builder’s preference and the site conditions determine which option is used. The structural consequence is the same in either case — both transfer the outer leaf load into the beam.

If neither option was covered in the original PorthouseDean scope and you need a detail issued, contact the team with the beam reference and the preferred method. A detail can be provided if required.

Get Details for Your Beam

PorthouseDean specifies bearing and shelf plate arrangements as part of structural packages for extensions and wall removals. Get a quote to have your project fully detailed.