Cold storage. Steel that doesn't get brittle at minus 25.

Where it fits

Three things change when steel goes below freezing.

Carbon steel that performs fine at room temperature can fail in tension at low service temperatures — fracture toughness drops as temperature drops, and the failure mode shifts from ductile to brittle. The CSA G40.21 "WT" notch-tough grades (e.g. 350WT) address this; they cost more but rate down to typical Ontario freezer service temperatures (-30°C and below). The other two changes: insulated panel (IMP) wall coordination so the structure doesn't compromise the thermal envelope, and finishes that handle frost cycles without delamination.

Common scopes

• Storage mezzanines — pallet storage in refrigerated and freezer zones. Typical cold-storage scope.
• Work platforms — sortation and pick decks in chilled processing zones.
• Mezzanine access stairs — same code envelope as ambient, but tread and finish choices shift.
• Outdoor steel stairs — for receiving / shipping side service, exterior galvanized.

Sub-zero design rules

• Notch-tough steel — 350WT-grade primary structure when service temperature drops below ~-15°C. Standard 300W can crack in tension under impact at low temp.
• IMP coordination — insulated panel walls don't carry structural load. Mezzanine columns either bear independently of the panels (typical) or use engineered penetrations that maintain the vapour barrier.
• Vapour barrier integrity — every column or beam penetration through a freezer wall is a thermal bridge and a potential moisture intrusion. We coordinate with the IMP installer on penetration detailing before fabrication starts.
• Frost-tolerant finish — galvanized handles freeze-thaw better than paint in cyclic service. For interior freezer-only (no warm cycle), shop primer or epoxy is fine; for thaw-cycle zones, galv adds margin.
• Tread choice — bar-grate is preferred — sheds frost, drains during defrost cycles, doesn't trap ice on the tread.
• Forklift access at -25°C — operators in freezer suits work slower; aisle widths and turning radius around stair towers shift slightly compared to ambient warehouse.

Typical project parameters

• Service temperature+5°C (cooler) / -25°C (freezer) typical
• Steel gradeCSA G40.21 350W (ambient) / 350WT notch-tough (sub-zero)
• Live load125 – 250 psf typical
• Treadbar-grate (preferred) / grip-strut
• Finishgalvanized (cycle service) / shop primer (freezer-only)
• IMP coordinationrequired at every wall penetration
• Lead time6 – 10 weeks from sign-off (notch-tough material)