A steel column is a vertical member that carries load from beams and floors down to the foundation, and the main types are wide-flange (W) columns, square and rectangular HSS, round HSS and pipe, concrete-filled pipe (Lally) columns, adjustable steel posts, built-up welded columns and composite steel-concrete columns. Commercial buildings mostly use W-shapes and HSS; houses mostly use HSS posts, pipe columns and adjustable columns. The choice depends on load, height, how the beams connect, appearance and the building code rules that apply.
This guide walks through each column type and section, where it fits, and what decides between them.
What a steel column does
A column carries mostly axial compression: the weight of everything above. In real buildings it also takes some bending, from beams connected off-centre, wind, or a frame that resists sway.
Unlike a beam, a column rarely fails by crushing. It fails by buckling: bowing sideways at a load well below the steel's yield strength. Buckling depends on:
- Unbraced length: the distance between points where the column is held sideways. Halving it greatly increases capacity.
- Stiffness of the section in its weakest direction (its minor axis).
- End conditions: how the top and bottom are held.
That is why column sections tend to be compact and balanced in both directions. A section that is very stiff one way and floppy the other wastes steel. Our post on HSS column load tables explains how effective length and capacity are read from tables.
Steel column sections at a glance
| Type | Example (Canadian name) | Strengths | Typical use |
|---|---|---|---|
| W-shape (I or H section) | W200x46, W250x67, W310x97 | Easy beam connections on flanges and web | Commercial and industrial frames, high-rise steel |
| Square HSS | HSS 102x102x6.4 | Equal stiffness both ways, compact, clean | Basement and deck posts, light frames, exposed columns |
| Rectangular HSS | HSS 152x102x6.4 | More stiffness in one direction; fits inside walls | Columns in stud walls, frames, mezzanines |
| Round HSS and pipe | 168.3 mm round HSS; NPS pipe | Equal in all directions; good looks | Exposed columns, canopies, parkades, bollards |
| Concrete-filled pipe (Lally) | Residential steel pipe filled with concrete | Widely available, simple to install | Basement columns in houses |
| Adjustable steel column | Screw-jack posts | Height can be adjusted | Basement posts within code limits, temporary shoring |
| Built-up or welded | WWF sections, plate boxes, laced columns | Sizes beyond rolled shapes | Heavy industrial, crane buildings, transfer columns |
| Composite | Concrete-filled HSS, concrete-encased W | Higher capacity and fire resistance | Taller buildings, heavy loads |
W-shape columns (I and H sections)
The wide-flange W-shape is the standard column in commercial steel buildings. For columns, designers favour the squarer, heavier W-shapes in each depth group, where the flange is about as wide as the section is deep. A W200x46, for example, is about 203 mm deep with a 203 mm flange, the classic "H" profile.
Why W-shapes work well as columns:
- Connections are simple. Beams bolt to the flanges or the web with shear tabs, clip angles or end plates.
- Splices are easy. Columns in multi-storey buildings are spliced every few floors with bolted or welded splice plates.
- A wide range of sizes lets the column step down in weight as the load drops toward the roof.
The weakness is the minor axis: an I-section bends and buckles much more easily about its web than about its flanges. Deep, narrow beam sections make poor columns unless they are braced in the weak direction. Our post on using an I-beam as a column covers when that works.
HSS columns: square, rectangular and round
Hollow structural sections are the other main column type, and the usual choice for houses and light commercial work.
- Square HSS has the same stiffness in both directions, which suits buckling well. HSS 89x89 and 102x102 sizes are familiar basement and deck posts; larger squares serve as building columns.
- Rectangular HSS fits inside a stud wall or gives more stiffness in the direction it needs.
- Round HSS is equal in every direction and is often chosen for exposed architectural columns.
HSS is named by outside dimensions and wall thickness. Its closed shape resists twisting and looks clean, but beam connections take more thought because there is no open flange to bolt into. Our comparison of W-beam vs HSS sets the two side by side on real section properties.
Pipe, Lally and adjustable columns
Steel pipe looks like round HSS but is named by nominal pipe size and wall schedule or weight class. It is used for columns, bollards and canopies.
Lally columns are steel pipe filled with concrete, long common in house basements. Their load capacity depends on the specific product and its height, so check the manufacturer's rating and the code rules before relying on one.
Adjustable steel columns (screw-jack posts or teleposts) have a threaded top for height adjustment. The 2024 Ontario Building Code limits where they can be used as permanent columns: Article 9.17.3.4. requires them to conform to CAN/CGSB-7.2 where the imposed load does not exceed 36 kN, and to be designed under Part 4 beyond that.
For residential steel columns generally, OBC Subsection 9.17.3. sets minimum pipe column sizes, end bearing plates and paint for exterior columns. Our post on basement column rules in the Ontario Building Code covers those rules in detail.
Built-up and composite columns
When a rolled shape is not big enough, or the column needs a special form:
- Welded wide-flange (WWF) and plate girder sections are welded from three plates into an H.
- Box columns are four plates welded into a closed square, used for very heavy loads.
- Laced and battened columns are two shapes held apart by lacing bars or batten plates. They are mostly found in older industrial buildings and crane structures.
- Concrete-filled HSS columns fill a steel tube with concrete so the two act together. CSA S16 has design rules for these composite columns.
- Concrete-encased steel columns wrap a W-shape in reinforced concrete, for strength, fire resistance or both. See steel columns and beams encased in concrete.
Column types by role
Drawings and engineers also describe columns by their job:
- Interior, exterior and corner columns carry different shares of floor and roof load and different wind effects.
- Gravity columns carry vertical load only and rely on bracing elsewhere for stability.
- Braced frame and moment frame columns are part of the lateral system and see large extra forces from wind and earthquake.
- Posts are short or lightly loaded columns: basement posts, deck posts, canopy posts.
- Stub columns start on a beam or transfer girder rather than a footing.
Whatever the type, every column needs a base plate at the bottom, a cap plate or connection at the top, and a load path into a footing or supporting member that can take the load. Sizing is a design decision for your designer or engineer, based on the load, height and bracing.
Steel columns made to your drawings
We fabricate W-shape and HSS columns and steel posts with base plates, cap plates and connections welded on, in our CWB certified shop, from shop drawings we prepare in-house. We supply and install basement beams and posts, and can prime or galvanize columns to suit. Send your drawings for a free takeoff and quote, or see our steel products.
Frequently asked questions
What is a steel column?
A steel column is a vertical member that carries load from beams, floors and roofs down to a footing or the structure below. It works mainly in compression, and its capacity is usually limited by buckling, so its length and bracing matter as much as its cross-section.
What are the types of steel column sections?
The common sections are wide-flange W-shapes (I or H sections), square and rectangular HSS, round HSS and pipe, concrete-filled pipe such as Lally columns, adjustable steel posts, welded built-up sections, and composite columns that combine steel and concrete.
Is an I-section good for a steel column?
Yes, a W-shape is the standard column in commercial buildings, but the squarer, heavier W-shapes are preferred over deep narrow beam sections. An I-section is much weaker about its minor axis, so it needs bracing or a squarer profile to work well as a column.
What steel column is used in a house basement?
Usually a square HSS post, a steel pipe column, or an adjustable steel column, with plates at top and bottom. The 2024 Ontario Building Code sets minimum sizes for steel pipe columns and limits on adjustable columns, and anything outside those rules is designed by an engineer.
