There is no single price per tonne for structural steelwork in the UK: a light, simple frame and a heavily connected multi-storey one can differ several-fold. Cost per tonne is driven by section complexity, connections, surface treatment, execution class, tonnage and current steel prices, not a fixed rate.
Why ‘per tonne’ is a moving target
Cost per tonne is a useful shorthand, but it bundles together material, fabrication labour, treatment, delivery and erection, and each of those varies with the job. The same tonnage of steel can carry very different amounts of work depending on how complex the frame is. So a quoted rate from one project rarely transfers cleanly to another.
The drivers that move the rate
- Steel material price: a commodity that moves with the market, so quotes are often time-limited
- Section type and complexity: plain beams and columns cost less to work than built-up, curved or tapered sections
- Connection complexity: the number and type of connections is one of the biggest drivers of fabrication labour per tonne
- Surface treatment: galvanising, a paint system or intumescent fire protection each add cost
- Execution class: a higher EXC class brings more welding control, NDT and documentation
- Transport and erection: craneage, site access and the lift plan all feed in if erection is included
- Programme: compressed or out-of-hours work carries a premium
- Tonnage: larger packages benefit from economies of scale; small one-off jobs carry more fixed cost per tonne
- Drawing quality: clear, complete drawings and detailing reduce risk pricing
Lighter steel isn't always cheaper per tonne
It's a common surprise: a lighter frame often costs more per tonne, not less. Light frames tend to have more connections and detailing relative to their weight, so there's more labour spread over fewer tonnes. Heavy, simple frames concentrate more weight into each fabricated piece and can carry a lower rate. Bare per-tonne comparisons between projects are therefore unreliable.
How to get a firm number
The only reliable figure is one priced against your actual drawings and specification. Send your GA drawings, member sizes, connection information and the execution class. Our guide to what to send for a quote covers it, and we'll come back with a real number rather than a rule of thumb. Start a quote.
Common questions
- How much does structural steel cost per tonne in the UK?
- There's no single rate. Cost per tonne depends on section complexity, the number of connections, surface treatment, execution class, tonnage, programme and the prevailing steel price. A simple heavy frame and a complex light one can differ several-fold, so a firm figure needs your drawings.
- Why is a lighter steel frame sometimes more expensive per tonne?
- Because lighter frames usually carry more connections and detailing relative to their weight, so more fabrication labour is spread over fewer tonnes. Heavier, simpler frames concentrate more weight per piece and can carry a lower rate per tonne.
- Does the execution class affect the price?
- Yes. A higher execution class (such as EXC3) brings more welding control, non-destructive testing and documentation, which adds cost. The class should match the structure rather than be over-specified.