Structural Steel Weight Takeoff from Member Schedules
Structural steel is priced by the tonne fabricated and erected. The main-member weight is straightforward; the connection steel is where estimates diverge.
Main members
Section mass comes from the steel tables (e.g. a W200×46 is 46 kg/m; a 100×100×10 angle is ~15 kg/m). Total by section size and by member type (columns, beams, purlins, bracing, girts).
Connection material
Add an allowance for plates, cleats, gussets, bolts, and welds. Rules of thumb:
| Structure type | Connection steel as % of main steel |
|---|---|
| Simple portal frames / sheds | 5–8% |
| Multi-storey braced frames | 10–15% |
| Moment frames, heavy transfer | 15–25% |
Base plates, stiffeners, and specials
Take these off individually — plate weight = area × thickness × 7850 kg/m³. Include holding-down bolts, shear keys, grout, and any embedded steel in the concrete package.
Wastage and coatings
- Fabrication wastage: 3–5% on plate-heavy work, 2–3% on rolled sections.
- Shop primer: by painted surface area (m²/tonne factors from the section tables), plus site touch-up.
- Galvanizing (if specified): priced per tonne, and it constrains member length to the bath size.
Deliverable
A steel BOQ by section size and grade with total fabricated tonnage, connection allowance, coatings area, bolts by grade and size, and erection as a separate line (often priced per tonne or per pick).
EngEst Pro’s Structural Calculator totals steel weight from your member list by section, adds a connection allowance and coating area, and outputs a tonnage-based steel BOM with bolts and base plates itemised.
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