How Much Weight Can a Lally Column Support?

There is no single number: a lally column's capacity depends on its diameter, wall thickness, steel grade and height. As an example of real manufacturer data, one US maker's published allowable loads for 8 ft columns range from about 11,500 lb (51 kN) for a light 3 in adjustable column to about 45,900 lb (204 kN) for a heavy-wall 4 in fixed column. In Ontario, adjustable columns (teleposts) built to CAN/CGSB-7.2 are only covered by the code up to 36 kN (about 8,100 lb) of imposed load, and anything above that has to be designed by an engineer or qualified designer.

This post explains what sets a column's capacity, how to read a manufacturer's load table, and how the load on your column is estimated. It is not a substitute for a design: if you're adding load, moving a column or changing a beam, that needs a qualified designer or engineer.

What sets a lally column's capacity

A steel column in a basement is loaded in compression. It can fail in a few ways, and the weakest one sets the capacity:

• Buckling. A slender column bows sideways and collapses well before the steel itself is crushed. This is usually what governs a basement column, and it's why height matters so much.
• Local crumpling of a thin wall. Very thin tubes can wrinkle at the ends or at a dent. Concrete fill in a traditional lally column helps prevent this.
• The ends. The plates, the adjustment screw on a telepost, and how the column bears on the beam and footing.

So capacity goes up with a larger diameter, a thicker wall and higher-strength steel, and goes down as the column gets taller. Damage changes everything: a rusted base, a dent or a bent tube means the published number no longer applies.

Manufacturer load table data: an example

Manufacturers publish load tables for their columns, and in the US these are often backed by an ICC-ES evaluation report. The table below is taken from one such report (ICC-ES ESR-1766, for Tiger Brand fixed and adjustable columns, reissued April 2026). The figures are allowable (ASD) loads for columns at about 8 ft, converted to kN.

Source: ICC-ES ESR-1766, Tables 2 and 3. Allowable loads; 1 kip = 1,000 lb = 4.45 kN.

A few things stand out:

• Wall thickness matters as much as diameter. A heavy-wall 3-1/2 in column outperforms a light-wall 4 in column.
• Adjustable columns rate lower than fixed columns of the same tube, partly because the screw assembly is part of the length.
• Height costs capacity. In the same report, a light 3 in adjustable column drops from 13,500 lb at its shortest listed length (76 in) to 6,600 lb at its tallest (145 in). That's less than half.

Why you can't just apply these numbers in Ontario

That table is for one manufacturer's products, evaluated against US codes. It's useful for understanding how capacity behaves, but it doesn't make a column acceptable here:

• Adjustable columns in Ontario houses must conform to CAN/CGSB-7.2 where the load is 36 kN or less (Article 9.17.3.4.(1)). A US rating above 36 kN doesn't raise that limit. Adjustable columns outside it must be designed under Part 4 (Sentence 9.17.3.4.(2)).
• Thin-walled tubes don't meet the default pipe column minimum of 73 mm diameter and 4.76 mm wall in Article 9.17.3.1. They're only permitted where their capacity is shown to be adequate, which is a job for a recognized rating or a designer.
• Canadian design under Part 4 works with factored loads and resistances to CSA S16, not the US allowable-load format, so a designer won't simply lift a number from a US table.

The number that matters for an existing column is on its own label. A CGSB-conforming telepost should show the standard number, the maximum allowable load in kN and the maximum extension. Our guide on whether teleposts can be permanent explains what to look for.

How much load is actually on your column

The other half of the question is the load. The Ontario Building Code's explanatory note to Article 9.17.3.4. describes the simple Part 9 method: the area of floor the column supports, multiplied by the floor live load, for each floor carried.

The supported area is:

• Half the joist span on each side of the beam, added together, multiplied by
• Half the beam span on each side of the column, added together.

A worked illustration, using the 1.9 kPa live load for residential areas in Table 4.1.5.3.:

With two floors above, that column is already past the 36 kN that CAN/CGSB-7.2 covers. The code's note makes exactly this point: with the floor loads and spans Part 9 allows, column loads can exceed 36 kN. The note also explains that dead load is left out of this Part 9 shortcut, and that a Part 4 design has to consider all the loads, including dead load. That's one reason an engineered column is often heavier than the shortcut suggests.

This is an illustration only, not a way to size a column. Point loads from walls, a roof bearing on the beam, or a beam that isn't continuous all change the picture. For the full process, see how to size a steel column for a house.

The column is rarely the only limit

Even a strong column only works if what's above and below it can take the load:

• The footing. A column must be centred on a footing that conforms to Section 9.15. (Article 9.17.2.1.). A column load on a thin slab with no footing is a common cause of cracked slabs and sagging floors. See lally column footing requirements.
• Bearing on a wood beam. The column's load concentrates on a small area of the beam. The top plate has to run the full width of a wood beam (Article 9.17.3.2.), and the designer checks that the wood won't crush.
• The connections. The manufacturer's report notes that connections to the foundation and the supported structure are outside its scope, and that the plates have to be checked separately. Columns also have to be fastened to the beam to prevent lateral movement (Sentence 9.17.2.2.(1)).
• Eccentric and lateral loads. Load tables assume the load comes straight down the centre of the column. A beam bearing off-centre, or a column that's out of plumb, reduces capacity.

The cap and base plates guide covers the ends in more detail.

When to get a column checked

Have a designer or engineer look at your columns before you:

• Remove or move a column, which lengthens the beam span and loads the remaining columns more heavily
• Add load above, such as a second storey, a heavy tile floor, a kitchen island with stone, or a new wall
• Replace an unlabelled post or one that has rusted at the base
• Remove a bearing wall upstairs, which can drop a new point load onto the basement beam

Don't try to jack a sagging floor back up with a telepost. Lifting a structure moves load into places that weren't designed for it and can crack walls, finishes and foundations. Changes to columns, beams or footings are structural alterations that normally need a building permit in GTA municipalities.

Steel posts sized for the load

When your designer or engineer specifies a post, we fabricate it: round or square steel sections cut to length with base and cap plates welded on, along with the beam it supports. We supply and install basement beams and posts across the GTA and Ontario, and engineering services are available for projects that need them. Send us your drawings or details for a quote, or browse our steel products.