What Size Steel Column Do I Need?
Quick Answer
Typically 100×100 UC or 152×152 UC for domestic use
Must be designed by a structural engineer for your specific loads and height
Important: Steel column sizing must be carried out by a qualified structural engineer. The sizes below are general guidance only and should not be used for design or construction purposes.
Common Domestic Column Sizes (General Guidance)
- Light load (single storey, short span beams): 100 × 100 UC 23
- Medium load (two storeys, typical spans): 152 × 152 UC 23 to UC 30
- Heavy load (three storeys or long spans): 152 × 152 UC 37 or 203 × 203 UC
Column vs Post
- UC (Universal Column): H-shaped section, designed for axial compression. Most common for structural columns.
- SHS (Square Hollow Section): Tubular, looks neater when exposed. Common for contemporary designs.
- CHS (Circular Hollow Section): Round tube, used for aesthetic columns.
Factors That Affect Column Size
- Axial load: Total weight transferred from beams above
- Effective height: Floor-to-floor height and end restraint conditions
- Eccentricity: Whether loads are applied centrally or off-centre
- Buckling: Slender columns can buckle under compression
Base Plate and Foundation
Every steel column needs a base plate welded to the bottom, bolted to the foundation. The foundation must be designed to spread the column load into the ground — typically a concrete pad foundation.
- Base plate (typical): 200×200mm to 300×300mm, 10–15mm thick
- Holding-down bolts: 4 × M16 or M20
- Pad foundation: 600×600mm to 900×900mm, 300–500mm deep
Cost Guide
- Steel column (fabricated with base plate): £200–600
- Installation: £300–800
- Pad foundation: £200–500
- Fire protection: £100–300
Last updated: April 2026