Wall Girts  for a Steel Workshop: The Frame Behind the Cladding

English Version

Title: Wall Girts QJ-1/QJ-2: LH280×150 at 3.2 mm, Holding Up a 15.9 m Wall

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Overview

A wall girt mark QJ is the horizontal steel member that carries the wall cladding between columns. Wind pushes on the wall panel; the panel hands that load to the girts; the girts hand it to the columns and the bracing. Without a properly sized girt system, wall panels oil-can, fasteners loosen, and the wall leaks.

This project uses high-frequency welded H-section girts in two sizes, arranged in rows with X-bracing on the tall walls.

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Member Schedule (from Drawing)

 

Mark	Section	Type	Grade
QJ-1 / QJ-1a	LH280×150×3.2×4.5	High-frequency welded H-section	Q355B
QJ-2	LH250×150×6.0×8.0	High-frequency welded H-section	Q355B

LH sections are light-gauge H-profiles: 280 mm deep × 150 mm flange × 3.2/4.5 mm walls for the standard girt; 250 × 150 × 6.0/8.0 mm for the heavier wall zone.

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Layout Data (from Drawing)

 

Item	Value (from drawing)
Wall frames shown	1# and 6# wall girt layouts
Column axes	① to ⑯
Girt elevations	3.320 / 11.500 / 12.000 / 15.000 / 15.900 m (1# wall); up to 21.000 m (6# wall)
Bracing	X-shaped cross bracing between girt rows
Spacing	Regular column bays, girts continuous across bays

The layouts show girt rows running horizontally across every bay, with X-bracing in the tall wall zones — the bracing takes the wind shear that the girts alone cannot.

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What the Wall Girt Does

• Carries cladding load: the wall panel spans between girts; girt spacing (typically 1.5–2.5 m) sets the panel span.
• Transfers wind to columns: wind pressure on the wall travels girt → column → foundation, and the X-bracing takes the in-plane shear.
• Holds openings: door and window frames bear on the girts; the girt layout must align with the opening grid.
• Supports wall accessories: downpipes, wall lights, and signage all anchor to the girt line.

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Advantages

1. Light and cheap — 3.2 mm web LH280 sections weigh roughly 8–10 kg/m; a hot-rolled H of the same depth weighs twice as much.
2. High-frequency welded H-section is straight and true — the welded box-like profile resists local buckling better than a cold-formed channel of the same weight.
3. Fast installation — girts bolt to cleats on the columns; a bay goes up in minutes with a small crane or a man-lift.
4. Works with any cladding — sandwich panels, single-sheet metal, or fibre-cement board all fix to the same girt line.
5. Easy to add openings — girt rows can be cut and framed around doors and windows at the design stage.

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Disadvantages / Limitations

1. Thin walls need careful handling — 3.2 mm webs dent during transport and erection; lifting points and stacking need control.
2. Local buckling governs — a deep thin-web girt fails by web crippling before it reaches yield; the section must be checked, not just sized by depth.
3. Welded H-sections need quality control — the high-frequency weld line is the weak point; weld penetration and coil quality must be verified per batch.
4. Corrosion protection required — thin sections lose capacity quickly to rust; galvanizing or a full coating system is essential.
5. Not a primary frame — girts carry cladding, not roof or crane loads; they cannot replace a column or a roof beam.

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Typical Use Cases

1. Steel workshop walls — 15.9 m tall wall panels on girt rows, as in this project's 1# wall.
2. Large industrial halls — 21 m high walls (6# wall) with X-bracing in the tall zones.
3. Warehouse external walls — long continuous walls with sandwich panels fixed to girt lines.
4. Renovation and extension walls — new girt rows added to an existing frame to carry new cladding.
5. Plant rooms and annexes — small wall frames where a light girt system replaces heavier structural members.

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Fabrication and Erection Notes

• Sections: LH280×150×3.2×4.5 and LH250×150×6.0×8.0, Q355B — verify the mill certificate and the weld-line quality per batch.
• Fabrication: cut to the girt schedule lengths; weld end plates and cleats in the shop; galvanize or prime before shipping.
• Erection: set girt rows to the elevations on the drawing (3.320 / 11.500 / 12.000 / 15.000–15.900 / up to 21.000); check level and line before fixing cladding.
• Bracing: install the X-bracing before cladding so the wall is stable during panel fixing.
• Cladding: keep girt spacing within the panel's span limit; seal fasteners with washers to avoid water ingress.
• Handling: use spreader bars for long girt lifts; do not drag girts on the ground.

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Bottom Line

Wall girts are the least glamorous part of a steel workshop and the one that decides whether the wall looks flat in ten years. QJ-1's LH280×150×3.2 and QJ-2's LH250×150×6.0 in Q355B carry the cladding, take the wind, and line up with every door and window. Size them for local buckling, protect them from rust, and the wall stays straight

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**Email**: eddie@zdsteels.com, wells@zdsteels.com