Yes, a lally column needs a footing. The 2024 Ontario Building Code requires footings under columns that bear on soil (Article 9.15.3.1.) and requires every column to be centred on a footing that conforms to Section 9.15 (Article 9.17.2.1.). For a typical house where columns are 3 m apart, the minimum pad area in Table 9.15.3.4. is 0.40 m² for one floor, 0.75 m² for two floors and 1.0 m² for three, adjusted for other spacings.
"Lally column" is a US name for a steel pipe column, often concrete filled. In Ontario the same job is done by teleposts (adjustable steel columns), fixed steel pipe columns and HSS posts. The footing rules below apply to all of them, because the code treats them as columns.
Why the footing matters more than the column
A basement column takes the load from a beam, which collects load from half the joist span on each side, sometimes over two floors. That load arrives on a base plate roughly the size of your hand. Soil can't carry that kind of concentrated pressure, so the footing's job is to spread it over enough ground to stop the column from settling.
When a column settles, the beam drops with it. The signs upstairs are sloping floors, doors that stick, and cracks in drywall over the beam line. So the footing is usually the part of a column installation that deserves the most attention, and it's the part people most often skip when they "just add a post."
What the 2024 OBC requires for column footings
These are the Part 9 rules that apply to a column footing in a house. Section and table numbers are from the 2024 Ontario Building Code (O. Reg. 163/24), Division B.
| Requirement | Where it is |
|---|---|
| Footings are required under columns that bear on soil or rock | 9.15.3.1. |
| Columns must be centred on a footing conforming to Section 9.15 | 9.17.2.1. |
| Footings rest on undisturbed soil, rock or compacted granular fill | 9.15.3.2. |
| Minimum footing area for columns | Table 9.15.3.4. |
| Area adjusted in proportion for column spacings other than 3 m | 9.15.3.7. |
| Thickness at least 100 mm and at least the projection beyond the supported element | 9.15.3.8. |
| Footing area doubled where a high water table sits in gravel, sand or silt | 9.15.3.4.(3) |
| Bond-breaking material between the slab and footings | 9.16.4.4. |
The column itself has its own rules in Section 9.17, including the 100 mm x 100 mm x 6.35 mm end plates, fastening at the top, and the load limit on adjustable columns. Those are covered in our post on adjustable steel columns and in our guide to basement column rules in the Ontario Building Code.
Lally column footing size: Table 9.15.3.4.
Table 9.15.3.4. gives minimum footing areas for columns spaced 3 m on centre. The square sizes in the right-hand column are our conversion of the area to a square pad, for orientation only.
| Floors supported | Minimum footing area (columns at 3 m o.c.) | Equivalent square pad |
|---|---|---|
| 1 | 0.40 m² | about 632 mm (25 in) square |
| 2 | 0.75 m² | about 866 mm (34 in) square |
| 3 | 1.0 m² | 1,000 mm (39 in) square |
Source: 2024 Ontario Building Code, Division B, Table 9.15.3.4.
Other column spacings. Article 9.15.3.7. says the footing area for column spacings other than 3 m is adjusted in proportion to the distance between columns. As an illustration, a column supporting one floor with columns 3.6 m apart works out to 0.40 x 3.6 / 3 = 0.48 m², roughly a 700 mm square pad. Spacing columns further apart to open up a basement makes each footing bigger, which is one reason a new beam layout usually comes with new footings. For how column spacing is set in the first place, see how far apart basement columns should be.
Floors supported counts the floors whose load comes down through the column. A bungalow's centre beam usually carries one floor. A two-storey house with a bearing wall stacked over the beam line can put two floors on the same column.
Footing thickness, soil and depth
Thickness. Article 9.15.3.8. sets footing thickness at not less than the greater of 100 mm or the width of the projection of the footing beyond the supported element. A column and its base plate are small, and the pad is wide, so the projection on each side is large. In practice that means a column pad is thicker than the 100 mm minimum people often quote. Your designer sets the thickness on the drawing.
What it sits on. The footing has to rest on undisturbed soil, rock or compacted granular fill (Article 9.15.3.2.). Loose material left in the bottom of a hand-dug hole doesn't qualify, and neither does old backfill.
Soil conditions. The Part 9 footing tables assume stable soil with an allowable bearing pressure of 75 kPa or more (Article 9.15.1.1.). Footings on filled ground, peat or sensitive clay (including leda clay, found in parts of eastern Ontario) must be designed under Section 4.2. Where gravel, sand or silt has a water table closer below the bearing surface than the footing width, the column footing area must be at least doubled (Sentence 9.15.3.4.(3)).
Depth. An interior basement column footing already sits well below the outside ground level, so it is normally deep enough by default. Exterior columns, such as deck or porch posts, are a different case, and their footing depth is governed by Article 9.12.2.2. and the frost conditions at the site.
Reinforcement. Part 9 does not prescribe rebar in plain footings, as our post on whether footings need rebar explains. Engineered column pads often are reinforced, and then the drawings set the bar size and spacing.
Lally column on a slab: why it doesn't work
A very common question is whether a lally column can sit on the basement floor. Under Part 9, the answer is no for an ordinary slab:
- Section 9.16 floors-on-ground do not support the structure. Article 9.16.1.1. limits the section to floors "that do not provide structural support for the superstructure."
- A slab that does carry structural loads must be designed under Part 4 (Article 9.16.1.2.), which means an engineer.
- The minimum Part 9 slab is only 75 mm thick (Article 9.16.4.3.), with nothing in the section about carrying point loads.
So a post standing on the slab with no pad under it is not a code-compliant column, regardless of the column's label or rating. Signs to watch for are a cracked or sunken slab around the base, or a post that has been shimmed at the top more than once.
The usual fix is a proper pad footing: the slab is cut out, the hole is excavated to undisturbed soil, the footing is inspected and poured, and the slab is patched around it with a bond break between the two. An engineer can sometimes design a thickened slab or other detail instead, but that is a design decision, not a site decision.
Lally column footing detail: how a typical install goes
On a renovation where posts are added or moved, the sequence usually looks like this. It is here so you know what to expect; this is structural work, it normally needs a permit, and it should follow a designer's or engineer's drawings.
- Design. The designer works out the load on each column and sizes the footings, posts and plates.
- Temporary support. The beam is shored on both sides before any existing post is removed.
- Slab and excavation. The slab is cut and the hole is dug to undisturbed soil at the size on the drawings.
- Inspection. The footing excavation is inspected before concrete goes in, if the permit calls for it.
- Pour and cure. The pad is poured, often slightly below the finished floor so the slab can be patched over the edges with a bond break.
- Set the column. The post is cut to length (or adjusted, for a telepost), set centred on the pad, fastened to the beam at the top and secured at the base as detailed.
- Patch and finish. Shoring comes out once the post is carrying the beam, and the slab is patched.
When a column footing must be engineered
The Part 9 footing sizes stop applying in several common situations. Article 9.15.3.3. limits the tables to supported joist spans of 4.9 m or less and floor live loads of 2.4 kPa or less, and Section 9.17 itself only covers columns under beams carrying up to two wood-frame floors with a supported joist length of 5 m or less. Expect an engineered footing when:
- A new beam spans further than the old one, so fewer columns carry more load each.
- Point loads come down from a wall, post or girder truss above.
- Joist spans exceed 4.9 m, or the floor carries heavy loads such as a tiled concrete topping.
- The soil is fill, peat, sensitive clay or wet, or the existing footing's size is unknown.
- The basement is being lowered or underpinned, which changes every footing in the house.
Replacing a post on an existing footing of unknown size is its own judgement call, and cost depends heavily on whether a new pad is needed. We break that down in the cost to replace or remove a lally column.
Steel posts made to your drawings
Once the footings are designed, we fabricate the steel posts with base and cap plates welded on, along with the beams and plates they connect to, and deliver across the GTA and Ontario. Engineering services are available for projects that need them. Send your drawings or measurements for a quote, or see our steel products for posts, beams and plates.
Frequently asked questions
Do lally columns need footings?
Yes. The 2024 Ontario Building Code requires footings under columns that bear on soil or rock (Article 9.15.3.1.), and Article 9.17.2.1. requires every column to be centred on a footing that conforms to Section 9.15. A basement slab on its own is not a footing.
How big does a lally column footing need to be?
For columns spaced 3 m apart, Table 9.15.3.4. of the 2024 OBC sets a minimum footing area of 0.40 m² when the column supports one floor, 0.75 m² for two floors and 1.0 m² for three. The area is adjusted in proportion for other column spacings, and your designer confirms the final size.
Can a lally column sit on a concrete slab?
Not on an ordinary basement floor slab. Part 9 floors-on-ground are not meant to support the structure, and a slab that does carry superstructure loads must be designed under Part 4 of the code. The normal detail is a separate pad footing under the column, with the slab poured around it.
How thick should a column footing be?
Under Article 9.15.3.8., a footing must be at least 100 mm thick and at least as thick as it projects beyond the element it supports. Because a column is small compared with its pad, that projection rule usually makes column pads thicker than 100 mm.
