A rigid frame is a moment-resisting steel frame of tapered columns and rafters that carries load without interior columns. It is the structural system behind most industrial buildings and warehouses in Ontario, because it produces the largest usable floor area for the least steel.
Why clear span decides everything else
Clear span is the first number to settle, because it drives the frame depth, the foundation reactions and a large part of the cost. It should come from how the building will actually be used, racking layout, aisle widths, turning radius for the material handling equipment, and any future reconfiguration you want to keep possible.
Single-span rigid frames are economical to roughly 45 m. Beyond that, a multi-span frame with interior columns is usually the better value, and clear widths well past 90 m are achievable that way. Paying for a clear span the operation does not need is one of the more common ways to overspend on an industrial building.
Pre-engineered versus conventional structural steel
A pre-engineered metal building is designed and fabricated as a system by the manufacturer: tapered plate frames optimised for the specific loading, cold-formed secondary framing, and a matched panel system. Conventional structural steel uses standard rolled sections detailed by a consulting engineer and fabricated to drawing.
For a straightforward warehouse envelope, pre-engineered is generally faster and cheaper. The design is largely automated and the material is optimised. Conventional steel earns its premium where there is heavy crane loading, complex geometry, unusual openings, significant future expansion in more than one direction, or architectural requirements the system cannot accommodate. We procure and build both, which means the recommendation is not tied to a product line.
Design standards and fabrication
Structural design follows Part 4 of the Ontario Building Code, with steel design to CSA S16 and cold-formed members to CSA S136. Snow, wind and seismic loading come from the site-specific climatic data for the municipality. Ontario snow loads vary substantially, and a building designed for one region cannot simply be relocated to another.
Fabricators require CSA W47.1 certification for welded steel construction. Verify it before award rather than after, along with the manufacturer's ability to supply a sealed design for the Ontario jurisdiction.
| Parameter | Typical range | Notes |
|---|---|---|
| Single-span clear width | 12–45 m (40–150 ft) | Economical range for a single-span rigid frame |
| Multi-span clear width | to 90 m+ (300 ft+) | With interior columns; usually better value above 45 m |
| Bay spacing | 7.6–9.1 m (25–30 ft) | Wider bays reduce frame count, increase secondary framing weight |
| Eave height | 6.1–12.2 m (20–40 ft) | Driven by racking height and material handling clearance |
| Roof slope | 1:12 to 4:12 | Lower slopes available with structural standing seam systems |
| Primary framing | Tapered welded plate, 350W | Depth varies along the member with the moment diagram |
| Secondary framing | Cold-formed Z-purlin / C-girt | Typically 1.5–2.5 mm, designed to CSA S136 |
| Design standards | OBC Part 4 · CSA S16 · CSA S136 | Fabricator certified to CSA W47.1 |
Indicative planning ranges. Final geometry follows the operational layout and the structural design for the site's climatic loading.