UB or UC Steel Column Wall Fixings: Full Detail

This article provides the complete specification for fixing a UC or UB steel column to an adjacent masonry wall. For a summary of the two connection methods, see How Do I Fix a Steel Column to the Wall?. This article covers the full detail including temporary construction conditions and masonry requirements.

Method A: Welded Frame Cramps Built Into Masonry

Frame cramps (mild steel angles or strap sections) are welded to the column flanges or web at 450 mm vertical centres. As the masonry is built up alongside the column, each cramp is built fully into a mortar bed joint.

Cramp specification:
– Mild steel flat or angle section, sized per structural drawings
– All welds: 6 mm fillet, full length of cramp face
– Embedded minimum 75 mm into masonry bed joint
– Stagger cramps between inner and outer leaves of cavity wall where applicable

Method B: Brackets and Chemical Anchors Through Existing Wall

For existing masonry that cannot be re-laid around the column, brackets are welded to the column flanges and fixed through the wall with resin anchors.

Bracket and anchor specification:
– Brackets: S275 mild steel, minimum 6 mm fillet welds
– Anchors: M12 diameter, minimum Grade 8.8 thread
– Chemical resin: structural epoxy or polyester resin, minimum embedment per manufacturer’s approval for masonry type
– Centres: 450 mm vertical, staggered to alternate flanges where possible

Temporary Bracing During Construction

The column must be temporarily braced during construction — before the masonry is fully built up and the permanent fixings achieve their full capacity. Temporary bracing (timber props, steel A-frames, or purpose-made column props) prevents the column from falling or moving while the permanent wall is being constructed.

Do not allow the column to stand without bracing while work is in progress.

Masonry Quality Requirements

The masonry must be adequate to receive the fixings. Before installing brackets or building cramps:

– Inspect the mortar joints — open, crumbling, or soft joints compromise the embedment capacity of cramps and the pull-out resistance of anchors
– Re-point or replace poor masonry before installing any fixings
– Do not install chemical anchors into soft, blown, or wet masonry — the resin will not cure correctly

Structural Specification Summary

| Item | Specification |
|—|—|
| All welds | 6 mm fillet |
| All bolts/anchors | Grade 8.8 black, M12 minimum |
| All plates and brackets | S275 structural steel |
| Fixing centres | 450 mm vertical |
| Material grades | Per structural calculations |

Out-of-Plane Restraint

Both methods provide out-of-plane restraint to the column and load-sharing with the adjacent masonry. Under horizontal loads (wind, impact), the column and the wall panel alongside it work together to resist the force. This is particularly important for tall or slender columns in exposed gable-end positions.

Party Wall Considerations

If the masonry wall is a party wall, party wall notices must be served before any drilling, bolting, or building-in of fixings into the party wall structure. Confirm the party wall position with your legal adviser before commencing.

Contact us or raise a Change Request if you have questions about the column wall fixing for your specific project.