A grade beam is a reinforced concrete beam running between column points at or just below grade. It ties the foundation together, carries wall and slab edge loads, and gets the building bearing below frost, which in Ontario is the requirement that shapes the whole detail.
Grade beam or spread footing and frost wall?
Both approaches get load below frost depth. The difference is how the load travels. A spread footing with a frost wall carries each column on its own pad and uses the wall mainly to retain and enclose. A grade beam spans between supports (piles, piers or footings) and is designed to carry load in bending.
Grade beams earn their place where soils are variable, where the building sits on piles, or where differential settlement across a large industrial footprint is the governing concern. They also handle the perimeter loading from a steel building cleanly: girts, cladding, dock equipment and slab edge all land on one continuous element.
Frost depth governs the section
Foundations bearing on soil must sit below the local frost line or be protected against frost action. Southern Ontario is commonly designed around 1.2 m; northern and eastern Ontario run deeper, up to roughly 1.8 m. Local municipal requirements and the geotechnical report take precedence over any general figure.
Moisture-rich clay soils are more frost-susceptible than granular ones, which is why two sites at the same latitude can carry different requirements. Where a heated slab makes it defensible, frost-protected shallow foundation approaches can reduce excavation, but that is an engineered decision, not a default.
Anchor bolts are the detail that costs money
Pre-engineered rigid frames arrive with base plates drilled to a fixed pattern. The concrete has to receive them within tight tolerance, and correcting a misplaced bolt group after the pour means chipping, epoxy anchors, engineered repair and a crane sitting idle.
Setting them accurately requires the manufacturer's anchor bolt plan and the frame reactions in hand before placement, templates rather than measured layout, and a survey check after the pour and before the steel arrives. This is straightforward when one party is responsible for both the concrete and the steel, and a recurring dispute when they are separate contracts.
| Parameter | Typical range | Notes |
|---|---|---|
| Bearing / frost depth | 1.2 m south · up to 1.8 m north | Below local frost line; municipality and geotechnical report govern |
| Concrete compressive strength | 25–35 MPa | Higher end where exposure class and load demand it |
| Exposure class | C-2 / F-2 typical | Exterior elements exposed to freeze-thaw and de-icing chemicals |
| Air entrainment | 5–8% | Freeze-thaw durability |
| Beam width | 300–600 mm | Driven by span between supports and wall loading |
| Anchor bolt tolerance | ±3 mm within group · ±6 mm group to group | Set from manufacturer templates; survey verified before steel arrives |
| Slab on grade | 125–200 mm | Thicker under racking legs, dock areas and equipment |
Indicative planning figures. Section, reinforcement and concrete class for any specific building are set by the structural engineer of record.