Structural steel is one of the most queried items in construction pricing, and one of the hardest to get a straight answer on. The cost of a steel beam depends on the section size, the span, how it's connected, what fire protection it needs, and who's fabricating and installing it. There's no single "price per beam" — but here are the real numbers.
Steel Beam Costs: Supply & Install
| Beam Size | Typical Use | Supply & Install |
|---|---|---|
| 152×89 UB | Small openings, lintels | £800 – £1,400 |
| 203×133 UB | Standard wall removal | £1,200 – £2,200 |
| 254×146 UB | Large openings, 4–5m spans | £1,800 – £3,000 |
| 305×165 UB | Wide spans, heavy loading | £2,500 – £4,000 |
| 356×171 UB | Commercial spans, portal frames | £3,000 – £5,000+ |
Steel Pricing Per Tonne
For larger steelwork packages — multi-beam projects, portal frames, mezzanines — steel is typically priced per tonne rather than per beam. The all-in rate covers detailing, fabrication, surface treatment, delivery, and installation.
| Component | Rate per Tonne |
|---|---|
| Steel material (sections) | £800 – £1,000 |
| Detailing & drawing | £150 – £300 |
| Fabrication | £400 – £650 |
| Surface treatment (primer) | £80 – £150 |
| Delivery | £50 – £120 |
| Installation (on site) | £500 – £800 |
| Fittings (cleats, bolts, baseplates) | 15–20% on weight |
| All-in rate | £2,800 – £3,800/T |
Smaller jobs (under 5 tonnes) tend to sit at the higher end of this range because the fixed costs — detailing, crane hire, mobilisation — are spread across less tonnage. Larger commercial packages can come in under £2,800/T where volumes justify it.
Fire Protection Costs
Any steel that's exposed in a habitable space needs fire protection — either intumescent paint (which swells when heated to insulate the steel) or fire-rated board encasement.
Intumescent paint for 30-minute fire rating: £30–£50/m² of steel surface area, or roughly £300–£600 per tonne. 60-minute ratings cost more — £50–£80/m².
Board encasement (Fireboard or similar): £40–£70/m² of steel surface area. Cheaper than intumescent for high-rating requirements but less aesthetically clean.
Portal Frames
For agricultural buildings, warehouses, and large-span structures, portal frames are the standard structural solution. A portal frame consists of columns and rafters connected by rigid joints, creating a clear-span interior without internal supports.
Portal frame costs in 2026 depend heavily on span, eaves height, and bay spacing, but as a guide the steel frame element (excluding cladding and foundations) typically costs £30–£55 per m² of floor area for standard spans of 12–25m. For a 500m² industrial unit, that puts the frame cost at £15,000 to £27,500.
What Affects the Price?
Access — tight sites, residential areas, or upper floors where crane access is difficult add to installation costs. If you need a HIAB (lorry-mounted crane) instead of a mobile crane, that changes the programme and the price.
Connections — bolted connections are cheaper to fabricate than welded. Complex connection details (moment connections, haunched rafters) increase detailing and fabrication time.
Corrosion protection — hot-dip galvanising costs £200–£400/T but gives superior long-term protection versus paint systems. Essential for exposed steelwork or agricultural buildings.
Programme — rush jobs cost more. Standard fabrication lead times are 4–6 weeks from approval of fabrication drawings. Expedited delivery attracts a premium.
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