A lally column is a round steel column, traditionally a steel tube filled with concrete, that stands under a beam and carries its load down to a footing. You'll usually find them in basements, spaced along the main beam that runs down the middle of the house. "Lally column" is an American name. In Ontario the same job is done by teleposts (adjustable steel columns) and fixed steel posts, and the Ontario Building Code simply calls them steel columns.
The term shows up constantly in renovation forums, inspection reports and US product listings, so it's worth knowing what it means, what it's made of and how it maps to what's in a Canadian basement.
Where the name comes from
The column is named after John Lally, who ran a construction business in the Boston area around the turn of the 20th century and patented composite columns: a steel shell filled with concrete. The name stuck, the way "Kleenex" did, and in the US "lally column" now gets used for almost any round steel basement column, filled or not.
That loose usage is why the term causes confusion. A homeowner calling the post in their basement a lally column might have:
- A concrete-filled steel tube with plates at each end (the original idea)
- A hollow steel pipe or tube cut to length with welded plates
- An adjustable steel column with a screw jack at one end
- A temporary jack post that was never meant to stay
These are not the same product, and the rules that apply to each are different.
What a lally column is made of and what it looks like
A typical lally column looks like a round steel pole, usually painted, running from the basement floor to the underside of a beam. Look closely and you'll usually see:
- A steel tube or pipe. US products are commonly 3 in, 3-1/2 in or 4 in in outside diameter. Wall thickness varies a lot from one product to the next.
- A top plate where it meets the beam. Under a wood beam this is a flat plate, sometimes with tabs or a U-shaped saddle to hold the beam. Under a steel beam it is usually bolted or welded to the flange.
- A bottom plate sitting on the footing, often buried in the basement slab so you only see the column disappear into the concrete.
- On adjustable types, a threaded screw and nut at one end, or a telescoping inner tube with a pin.
Our guide to lally column sizes covers diameters, wall thickness and heights.
Are lally columns hollow or filled with concrete?
Both exist. In a concrete-filled column, the concrete shares the compression load and stiffens the thin steel shell so it is less likely to crumple locally. That let early lally columns use a relatively light tube.
Many columns in use today are hollow: adjustable teleposts, and fixed steel posts made from pipe or square HSS (hollow structural section). Hollow is not a defect. A steel post with the right diameter, wall thickness and length for its load does the job without any fill. What matters is the column's rated or designed capacity, not whether you can hear concrete when you tap it.
What a lally column does in a house
Most houses with a basement have a main beam (girder) running the length of the house, roughly down the middle. The floor joists of the first floor sit on the foundation walls at their outer ends and on this beam in the middle. Columns hold the beam up at intervals.
The load path goes like this:
- Floors, walls and sometimes the roof above push down on the joists.
- The joists deliver about half their load to the beam.
- The beam carries that load to the columns.
- Each column concentrates its share onto a footing under the slab, which spreads it onto the soil.
That's why a column is only as good as what's above and below it. A column on a thin slab with no footing, or one that isn't fastened to the beam, isn't doing its job properly no matter how strong the steel is. The Ontario code requires every column to be centred on a proper footing, not just set on the slab.
The spacing between columns is the span of the beam, and the two are designed together. Wider spacing needs a deeper or heavier beam and puts more load on each column.
Lally columns in Canada: teleposts and steel posts
You won't find the word "lally" in the 2024 Ontario Building Code. Section 9.17. sets rules for steel, wood, masonry and concrete columns in houses. For steel columns, the main points are:
- Steel pipe columns need an outside diameter of at least 73 mm and a wall thickness of at least 4.76 mm, unless another size is shown to have adequate capacity (Article 9.17.3.1.).
- End plates of at least 100 mm by 100 mm by 6.35 mm are required at each end, with the top plate running the full width of a wood beam (Article 9.17.3.2.).
- Adjustable steel columns must conform to CAN/CGSB-7.2 where the load is 36 kN or less, and must be designed under Part 4 of the code otherwise (Article 9.17.3.4.).
- Every column must be centred on a proper footing and fastened to the beam it supports (Subsection 9.17.2.).
In practice, Ontario basements have three common types:
| What it's called | What it is | Typical use |
|---|---|---|
| Telepost | Adjustable steel column with a screw or telescoping tube and pin | Original basement columns in many houses |
| Steel pipe column | Fixed round pipe with welded end plates | Older houses, replacements |
| HSS steel post | Square or round hollow structural section cut to length with welded plates | Engineered renovations, new beams |
All the code details are in our guide to basement column rules in the Ontario Building Code, and whether an adjustable one can stay for good is covered in can teleposts be permanent.
Lally column vs jack post
The difference that matters most is between a permanent column and a temporary jack post.
- A permanent column is rated or designed for the load it carries, sits on a footing and is fastened top and bottom. In Ontario, that's a CGSB-conforming telepost within its load limit, or a fixed steel post sized for the job.
- A temporary jack post is a shoring tool used to hold a beam up while work is done. Many are not labelled for permanent use at all.
The problem comes when a temporary post becomes permanent by default. A common find in older houses is a jack post installed decades ago to fix a sag, with no footing and no label. The first thing to check on any adjustable column is the label, which should reference CAN/CGSB-7.2 and show the maximum load and extension.
Signs a lally column needs attention
Columns are simple, but they do fail, usually at the bottom where moisture collects. Get the column looked at if you see:
- Rust eating into the base or the bottom of the tube, especially where it disappears into a damp slab
- A bent, bowed or out-of-plumb column
- Cracks in the slab around the base, or a column that has sunk
- A loose top with shims, wood blocks or a gap between the plate and the beam
- No label on an adjustable column, or a missing pin
- A sagging floor above the column line
Some of these are a simple replacement; others point to a footing or beam problem. Our guides to replacing lally columns and whether you can remove one to open up a basement go through the options. Any change to a column is structural work: the beam needs temporary support first, and moving or removing a column needs a qualified designer or engineer and, in GTA municipalities, a building permit.
Steel posts made to your drawings
We fabricate HSS and steel posts for basements with base and cap plates welded on, and we supply and install basement beams and posts across the GTA and Ontario. If you have drawings or measurements for a replacement or a new beam, send them to us for a quote, or see our steel products for what we make.
Frequently asked questions
What is a lally column used for?
A lally column is a vertical steel post that holds up a beam, most often the main beam or girder in a basement. It takes the load the beam collects from the floors above and passes it down to a footing under the basement slab.
Are lally columns filled with concrete?
The original lally column was a steel tube filled with concrete, and many sold in the US still are. Plenty of steel basement columns today are hollow, including most adjustable teleposts and fixed HSS posts. Either can be acceptable if it has the capacity for the load.
What is a lally column called in Canada?
The Ontario Building Code doesn't use the name. It calls them steel columns or steel pipe columns. On site, adjustable ones are called teleposts, and fixed ones are usually called steel posts or HSS posts.
Can you remove a lally column?
Not without replacing what it does. Removing a column changes the beam span and the loads on the remaining columns and footings, so it needs a design from a qualified designer or engineer and normally a building permit.
