What is a column?
A column is a vertical load-bearing element that transfers forces from above (beams, floors, roof) down to the foundation. In construction, columns are the vertical counterparts of beams: beams carry loads horizontally, columns carry loads vertically.
Column vs. stud vs. post
These terms are often used interchangeably, but there are subtle differences:
| Term | Material | Context |
|---|---|---|
| Column | Concrete, steel, or masonry | Structural engineering term, load-bearing structure |
| Stud | Wood | Timber frame construction, window frames |
| Post | Wood or steel | Pergolas, carports, arbours |
| Pillar | Stone or concrete | Decorative, often freestanding |
In practice: for a concrete or steel structure you say “column”, for a wooden structure you would more likely say “post” or “stud”.
Where do columns appear?
In residential construction
- Load-bearing columns in an open-plan layout where no load-bearing walls are desired
- Basement columns that support the ground floor
- Facade columns at large window openings
In DIY projects
- Pergola — The posts (wooden columns) support the roof
- Carport — Freestanding columns with a roof structure above
- Garage — For a wide garage door opening, a steel column is sometimes used instead of a wide masonry pier
- Veranda — The columns (posts) form the skeleton of the structure
Materials
Wooden column
Most commonly used in garden construction and DIY:
- Common dimensions: 100×100 mm, 120×120 mm, 150×150 mm
- Wood species: Douglas fir, pressure-treated spruce, or hardwood
- Always place on a post anchor (not directly on concrete or in the ground)
Steel column
For large loads or slender structures:
- HEA or HEB profiles for heavy loads
- Box sections (square tube) for a sleek appearance
- Often used for garage doors with large spans
Concrete column
In professional construction:
- Reinforced concrete, cast in situ or prefab
- Square or round
- Not common in DIY projects
Calculation
The load-bearing capacity of a column depends on:
- Material — Steel supports more than wood at the same dimensions
- Cross-section — The thicker, the greater the load-bearing capacity
- Buckling length — The longer the column, the sooner it can buckle (deflect). A 3-metre column supports less than the same column at 2 metres.
- End fixity — How the column is connected top and bottom. A fixed column is more stable than a pinned one.
> Rule of thumb for wood: A 100×100 mm Douglas fir column at a height of 2.5 metres can support approximately 2,000-3,000 kg. For exact calculations, always consult a structural engineer.
Common mistakes
- Column too slender — A column that is too thin for its height can buckle (deflect and fail)
- Wood in the ground — Even pressure-treated wood rots when placed in the ground. Use a post anchor.
- No bracing — Columns alone cannot resist horizontal forces. Use braces, cross-bracing, or rigid connections.
Related terms
- Post
- Beam
- Girder
- Post anchor
- Fence post