Steel Beam Bearing Length on Concrete and Masonry: Ontario Code Rules

Under the 2024 Ontario Building Code, a beam in a house needs even and level bearing at least 89 mm long at each end (Article 9.23.8.1.), and a beam supported on masonry needs at least 90 mm (Article 9.20.8.3.). Those are minimums. The code also requires the bearing area to be big enough for the load, and beams on masonry need a solid block of masonry or concrete beneath them, so the real bearing detail is usually more than a length.

This guide covers what the Part 9 rules say about seating a steel beam on concrete foundation walls, block, brick and columns, and where an engineer takes over.

Minimum bearing for a steel beam: the numbers

Source: 2024 Ontario Building Code (O. Reg. 163/24), Division B, Part 9.

Two things are easy to miss. First, "even and level" is part of the requirement, not a nicety: a beam rocking on a high spot or sitting on a sloped pocket concentrates the load on an edge. Second, 89 or 90 mm is a floor, not a target. A heavy steel beam carrying two floors, or a beam on weaker masonry, may need a longer bearing or a plate to spread the load, and that comes from design.

Steel beam to concrete wall connection: beam pockets

In most Ontario basements the main beam ends sit in pockets formed or cut into the poured concrete or block foundation wall. A few points matter at the pocket:

• Solid bearing below. On block walls, the code calls for at least 190 mm depth of solid masonry under the beam (Sentence 9.15.5.2.(1)). Hollow cores directly under a beam end are not solid bearing, so the cores are filled or solid units are used as the design specifies.
• Pilasters on thin block walls. Where a beam frames into a unit masonry foundation wall 140 mm thick or less, a pilaster is required (Article 9.15.5.3.).
• Weather protection. When the pocket puts the beam end below the top of the wall, the end must be protected from the weather (Sentence 9.15.5.2.(2)). On a steel beam that usually means primer or paint on the embedded end and keeping it from sitting in water.
• Shimming. Steel beams are levelled on steel shims or a grout bed as detailed. Wood packing under a steel beam end can crush or rot over time, which is why designers generally avoid it.
• Pocket depth. The pocket must be deep enough for the full bearing length, with a little room so the beam can be set without forcing it. Measure the actual pockets before the beam is cut.

On poured concrete walls, an engineer will check the concrete's bearing capacity under the beam to CSA A23.3 and may call for a steel bearing plate, anchors or a cast-in plate, especially for retrofits where a pocket is cut into an existing wall. If you're installing a new basement beam, our guide to the cost to install a steel beam in a basement walks through the whole job.

Can a steel beam sit on brickwork?

It depends on what kind of brickwork.

Solid loadbearing masonry (two or more wythes bonded together, common in older Ontario houses) can carry a beam if the masonry is designed for it. The code requires enough bearing area for the load, at least 90 mm of end bearing, and where the wall or wythe is under 190 mm thick, a pilaster with at least 190 mm depth of solid masonry or concrete under the beam (Articles 9.20.8.3. and 9.20.8.4.). Old soft brick and lime mortar often need a spreader under the beam end, and the masonry's condition should be checked before any new load goes on it.

Brick veneer is a different thing. It's a single layer of brick tied back to the wood or steel frame, and it carries its own weight, not floors or roofs. A beam should not bear on veneer. Where a beam lands at an exterior veneer wall, it bears on a post, column or the foundation behind the brick.

Concrete block walls follow the solid-bearing rule above: the beam bears on solid masonry or filled cores, never on the thin face shells of hollow block.

Steel beam on a padstone, bearing plate or column

Padstones. Many searches for steel beam bearing come from UK advice, where a beam end sits on a concrete padstone. Ontario's code doesn't use the word, but the idea is the same as its requirement for solid masonry or concrete under a beam: a solid, strong block that spreads a concentrated load into weaker masonry below. On a renovation, the designer decides whether a precast block, a poured concrete bearing, filled cores or a steel plate does that job.

Bearing plates. A steel plate under a beam end spreads the load over a wider area of concrete or masonry and gives a flat, level seat. Plate size and thickness come from the engineer's calculations, not from a rule of thumb. Our post on column base plate design under CSA S16 covers how plates are sized for columns, which follows similar thinking.

Steel columns. Where a steel beam bears on a steel post, Article 9.17.3.2. normally requires a 100 mm x 100 mm x 6.35 mm end plate at each end of the column, but the top plate can be left off when the column supports a steel beam and the column is attached to the beam. In practice most posts under steel beams have a cap plate bolted or welded to the bottom flange.

Concrete columns. Part 9 concrete columns must be at least 200 mm x 200 mm, or 230 mm in diameter if round (Article 9.17.6.2.). The beam is seated and fastened as detailed by the designer.

When the beam itself governs the bearing

So far we've talked about the support crushing. The beam can be the weak point too. At a bearing, the whole end reaction passes through the beam's thin web into the bottom flange. With a heavy load and a short bearing, the web can yield or cripple locally. CSA S16, the Canadian steel design standard, has checks for exactly this, and when they fail the fix is a longer bearing, a heavier section or bearing stiffeners welded between the flanges over the support.

That is engineering territory. If your drawings show stiffeners at the bearings, they're there for a reason, and they're a normal shop item for a fabricator. For the Part 9 tables and the conditions they assume, see our steel beam span tables for Ontario homes.

Steel beam foundation details checklist

Before a steel beam is ordered and installed, confirm:

• Bearing length at each end from the drawings, and that the pockets or seats are long enough.
• What the beam sits on: concrete, solid masonry, filled block, a plate or a post.
• Bearing plates, shims or grout called for, and their sizes.
• Stiffeners at bearings or under point loads, if shown.
• Corrosion protection for beam ends in pockets or exterior locations. Exterior steel beams must be shop primed with rust-inhibitive paint (Article 9.23.8.2.).
• Posts and footings under intermediate supports. Our guide to lally column footing requirements covers those.
• Overall length: clear span plus bearing at both ends, measured on site.

Moving or adding bearing points, cutting new pockets or changing a beam is a structural alteration. It needs a qualified designer or engineer and, in GTA municipalities, a building permit.

Getting the beam made to fit its bearings

We fabricate steel beams cut to the length on your drawings, with bearing plates, stiffeners, cap plates and holes for nailers as detailed, and deliver across the GTA and Ontario. Engineering services are available if your project needs them. Send us your drawings or beam schedule for a quote, or see our steel products for beams, posts and plates.