Can You Remove a Lally Column to Open a Basement?

Yes, you can usually remove a lally column to open up a basement, but never by itself: the column holds up the main beam, and taking it out makes the beam span twice as far if it was a middle support. That normally means an engineered new or reinforced beam, heavier posts and bigger footings at the supports that remain, temporary shoring while the work is done, and a building permit. Moving a column a short distance, or replacing several with fewer, is often easier than removing one outright.

Here's what changes when a column comes out, the options worth considering and how the job is done.

What a lally column is actually doing

Most Ontario houses have a main beam, or girder, running down the middle of the basement. The floor joists bear on it, and it carries a share of every floor above, plus any walls and posts that sit on that line. The beam rests on the foundation walls at its ends and on a row of steel columns in between.

Each column takes the beam's load at that point and delivers it to a footing under the slab. The column is the visible part of a load path that runs from the roof down to the soil. Pull it out without replacing that path, and the beam sags, the floors above crack and, in the worst case, something fails.

It's worth knowing what kind of column you have before you plan anything. Some basements have adjustable jack posts (teleposts) that were put in as temporary supports and never replaced, and those are often the first thing an engineer flags, whether or not anything is being removed.

What happens to the beam when a column goes

Take a beam on columns 3 m apart. Remove one column and that part of the beam now spans 6 m. Doubling a span doesn't double the demand on the beam:

• Bending in a beam carrying a uniform load grows with the square of the span, so it's about four times larger.
• Sag grows with the fourth power of the span, so it's about sixteen times larger.

The Ontario span table shows what that means in steel. In Table 9.23.4.3 of the 2024 OBC, with a 4.2 m supported joist length and one storey supported, a W150x22 reaches 4.8 m and a W200x27 reaches 6.3 m. So a W150x22 that was comfortable over 3 m columns is not enough for 6 m, and a heavier, deeper section is needed. With two storeys above, the jump is bigger again. If your existing beam is built-up wood, it's very rarely adequate for the doubled span.

These table values only apply to simple floor beams within the code's conditions. Columns often sit under point loads from walls or posts above, which puts the design outside the tables and into an engineer's hands. The table also assumes the beam's top flange is braced by the joists bearing on it, which a flush beam may not satisfy without extra detailing.

Your options for opening up the space

Removing a column is one of several ways to get the open basement you want:

• Remove one column and replace the beam, or reinforce it, for the longer span.
• Move a column. Shifting a post to the edge of a future rec room, or into a wall line, often needs a smaller beam change than removing it. The new location still needs a footing and a beam check.
• Replace several columns with fewer. On a full renovation, it's often more efficient to redesign the whole beam line at once: one new steel beam on fewer, well-placed posts.
• Clear-span the basement. A beam sized to run from foundation wall to foundation wall removes the interior columns entirely. It's the most open result and usually the deepest beam.
• Go flush. Where headroom matters, the new beam can be set within the joist depth, with the joists hung from its sides, so there's no dropped beam at all.

Removal isn't always the best answer. It gets harder, and sometimes impractical, when:

• The column sits under a point load, such as a post or bearing wall above that lands right on it
• Headroom is already tight, so a deeper beam would leave a ceiling too low to use
• The foundation wall pocket can't take more load without rebuilding it
• Ductwork or plumbing runs along the beam line and would have to be rerouted around a deeper section

For how column spacing and beam size trade off against each other, see how far apart basement columns should be.

What the remaining columns and footings need

When a column goes, its load goes to the supports that remain. Each of them now carries more, which is where the hidden part of the job is.

• Columns. Under Article 9.17.3.1 of the 2024 OBC, a steel pipe column must have an outside diameter of at least 73 mm and a wall at least 4.76 mm thick, unless another size is shown to have adequate capacity. Under Article 9.17.3.4, adjustable steel columns must conform to CAN/CGSB-7.2 where the load doesn't exceed 36 kN, and above that they must be designed. A column carrying a doubled load may need a heavier section.
• End plates. Article 9.17.3.2 calls for steel plates at least 100 x 100 x 6.35 mm at each end of a steel column, with exceptions where the column supports a steel beam and is attached to it.
• Footings. Table 9.15.3.4 sets minimum column footing areas for columns spaced 3 m apart, and Article 9.15.3.7 requires the area to be adjusted in proportion to the actual spacing. Wider column spacing means bigger footings. Existing pads are often too small for the new load, so new footings are poured before the new posts go in.
• Bearing at the walls. Where the beam sits on the foundation wall, the pocket and bearing have to suit the new beam.

Our posts on basement column rules in the Ontario code and lally column footing requirements go into these rules in more depth.

How a column removal is done

This is structural work for a contractor working from engineered drawings, not a DIY job. So you know what to expect, the usual sequence is:

1. Design. An engineer or qualified designer sizes the new beam, posts and footings and prepares drawings.
2. Permit. The drawings go to the building department. Structural alterations need a permit; the permits guide explains how that works in GTA municipalities.
3. Footings. The slab is cut where new posts will land, and new footings are excavated, inspected and poured.
4. Shoring. Temporary supports hold the floor on both sides of the beam line while the structure is changed.
5. New beam and posts. The new or reinforced beam goes in, the permanent posts are set on the new footings, and the connections are made.
6. Remove the old column, then the shoring, once the new structure carries the load.
7. Inspection and finishing.

Garage columns follow the same logic, with extra constraints from the door and any room above. For what drives the budget for these jobs, see cost to replace or remove a lally column.

Beams and posts for your basement

We supply, fabricate and install steel beams and posts for basements, with cap and base plates welded on and connections ready to install. Send us your engineer's drawings for a quote, or tell us about the column you want gone if you don't have drawings yet: engineering services are available for projects that need them. See our steel products for the beams, posts and plates we make.