Installing a lally column in a basement is a short job on a long list: the beam is shored, a proper footing is put in under the slab, a column is made or set to the exact height, and it is centred, plumbed and fastened to the beam at the top and secured at the base. In Ontario, the column must sit on a footing that meets the code (a basement slab isn't one), carry a steel plate at each end of at least 100 x 100 x 6.35 mm, and be fastened to the beam it supports. Because adding a column is a structural change, it normally needs a building permit and drawings.
This post walks through the process so you know what to expect and who does what. It's not a DIY guide: shoring a loaded beam and pouring a structural footing belong with a qualified contractor working from a designer's or engineer's drawings.
"Lally column" is a US term for a steel pipe column, often concrete-filled. In Ontario basements you'll mostly see adjustable steel columns (teleposts) or fixed steel posts made from pipe or HSS. The installation sequence is the same for all of them.
Why the column is going in
Columns get added in a basement for a handful of reasons, and the reason shapes the design:
- A new beam is going in, for example after a basement wall is removed, and it needs supports along its length.
- A beam is sagging or bouncy and the designer wants to shorten its span with an extra support.
- A wall above is being removed and its load now comes down as a point load that needs a column underneath.
- A temporary post becomes permanent, such as a jack post left from an old repair.
Each new column shortens the beam span, takes a share of the floor load and sends it straight down to its own footing. That's why the column, its footing and the beam are designed together. Spacing is covered in how far apart basement columns should be.
Permits, drawings and who designs it
Ontario's Building Code Act requires a permit to construct, and "construct" includes the installation, material alteration or repair of a building. Adding a structural column with a new footing falls squarely in that. Your building department will confirm what it needs.
The design comes from a designer or engineer:
- Under Part 9. Section 9.17 of the 2024 OBC covers columns under beams carrying up to two wood-frame floors, where joists bearing on the beam have a supported length of no more than 5 m and the live load is no more than 2.4 kPa. Inside that scope, the prescriptive rules for columns and footings apply.
- Under Part 4. Columns outside that scope, or carrying point loads from posts above, are engineered.
- Teleposts have a limit. An adjustable steel column must conform to CAN/CGSB-7.2 and is limited to an imposed load of 36 kN (Article 9.17.3.4). Above that, a fixed post designed under Part 4 is used. See whether teleposts can be permanent.
Step 1: Temporary shoring
Before any slab is cut under a loaded beam, or any existing post is removed, the beam is supported on temporary shores, usually one on each side of the new column location.
- Shores bear on something solid, not on a soft spot or on top of a planned excavation.
- They are snugged to hold the beam where it is, not to raise it.
- They stay in until the new column is set, fastened and carrying the beam.
If the beam is already sagging, the designer decides whether it is left where it is or brought up gradually. That's an engineering call, because lifting a floor moves loads into walls and foundations.
Step 2: The footing
This is where most of the work is. Article 9.17.2.1 of the 2024 OBC requires every column to be centrally located on a footing conforming to Section 9.15. In practice that means:
- Cutting out a section of the slab at the column location.
- Excavating to undisturbed soil at the size and depth on the drawings.
- A footing inspection before concrete, if the permit calls for one.
- Pouring the pad and letting it cure before it is loaded.
- Patching the slab around it.
The code gives minimum footing areas for columns in Table 9.15.3.4, adjusted for column spacing. Our guide to lally column footing requirements goes through the sizes, thickness and the reasons a column on a bare slab doesn't work.
Step 3: Measuring and making the column
Measure after the shoring is in, at the exact column location, from the top of the footing (or finished slab, depending on the base detail) to the underside of the beam. Measure on two sides; floors and beams are rarely perfectly level.
Then the column itself:
- Fixed steel post. Pipe or HSS cut to the measured length with base and cap plates welded on in the shop. Steel pipe columns under Part 9 need at least a 73 mm outside diameter and a 4.76 mm wall (Article 9.17.3.1). Other sections, including square HSS, are allowed where their capacity is shown to be adequate.
- Telepost. A labelled CAN/CGSB-7.2 column adjusted to height within its rated extension, with its pin and screw set as the manufacturer requires.
- Concrete-filled lally column. Common in US stores. If one is used, it must still meet the Ontario rules for size, plates, footing and fastening.
End plates. Article 9.17.3.2 requires steel plates of at least 100 x 100 x 6.35 mm at each end. Under a wood beam, the top plate must extend across the full width of the beam, which for a three-ply built-up beam is wider than 100 mm. Under a steel beam, the top plate can be omitted where the column is attached to the beam another way.
Step 4: Setting, plumbing and fastening
- Centre it on the footing and directly under the beam.
- Plumb it in both directions. A leaning column carries load eccentrically and can push its top or bottom sideways.
- Fasten the top. Article 9.17.2.2 requires the column to be securely fastened to the beam. Under a wood beam that is usually lag screws up through holes in the cap plate. Under a steel beam it is bolts or welds as detailed. Our post on connecting a steel post to a wood beam covers the options.
- Secure the base as the drawings show, whether that is anchors into the footing or a base plate set before the slab patch is poured around it.
- Transfer the load. Shores are released slowly so the beam settles evenly onto the new column, then removed.
Columns also have to be laterally supported against racking (Sentence 9.17.2.2.(2)). In a basement that normally comes from the fastened connection at the top and the footing at the bottom.
Step 5: Inspection and finishing
If there's a permit, the structural work is inspected before it's covered. Don't box in the column or close the ceiling until the inspector has seen the column, its plates and its fastening.
After that:
- Paint bare steel, especially in a damp basement.
- Keep the base dry. Water standing around a column base is the main reason basement columns rust out.
- Leave a telepost label visible if you box the column in, so it can be identified later.
Common mistakes to avoid
| Mistake | Why it matters |
|---|---|
| Column set on the slab with no footing | Slab cracks and settles under the point load |
| Stack of wood shims at the top | Shims crush and the beam drops |
| Top plate narrower than the beam | Fails the full-width rule and crushes the beam edges |
| Column not fastened to the beam | Can be knocked out of position or shift over time |
| Telepost extended past its rating, or unlabelled | No longer the tested, permitted column |
| Using the column to jack a sagging floor | Moves loads into parts not designed for them |
| Column off-centre on its footing | Uneven bearing and possible footing rotation |
Getting your column made and installed
We fabricate fixed steel posts cut to your measured height with base and cap plates welded on, and we supply and install basement beams and posts. Engineering services are available for projects that need them. Send us your drawings, measurements or photos for a free quote, or see our services for how we handle a job from drawings to installation.
Frequently asked questions
Can a lally column sit on the basement floor slab?
No. Article 9.17.2.1 of the 2024 Ontario Building Code requires columns to be centred on a footing that conforms to Section 9.15. A typical basement slab is not a footing, so the slab is cut and a pad footing is poured under the column.
Do I need a permit to install a lally column?
Usually. Adding a column changes the structure of the house, and Ontario's Building Code Act requires a permit to construct, which includes material alteration. Ask your municipal building department; a new column with a new footing almost always needs one.
How is a lally column attached to the beam?
Through a steel plate at the top of the column. Under a wood beam, the plate must cover the full width of the beam and is fastened up into it, usually with lag screws. Under a steel beam, the column is bolted or welded to the beam as detailed on the drawings.
Can I use a lally column to lift a sagging beam?
No. A column is set to hold the beam where it is. Jacking a sagging floor back up moves loads into walls, finishes and foundations that weren't designed for them, so any lifting is planned by an engineer and done gradually by a contractor.
