Ask five people what a steel beam costs and you'll get five answers - because "a steel beam" can mean anything from a single lintel to a welded frame with fire protection, delivered through a terraced house and installed on a Saturday. The good news is that the price is built from a handful of predictable parts. Understand them and you can compare quotes properly and avoid paying for things you don't need.
1. The steel section
Structural steel is bought by weight, so the section your structural engineer specifies matters. A universal beam is described by depth, width and weight per metre - a UB 203x133x25 weighs roughly 25 kg per metre, a UB 305x165x40 roughly 40 kg per metre. Longer spans and heavier loads need heavier sections. Steel prices move with the market, but for most domestic beams the material is a modest share of the total.
2. Fabrication
This is where most of the cost sits. Cutting to length, drilling bolt holes, welding end plates, cleats and stiffeners, and adding splices so a long beam can be carried through a narrow hallway all take workshop time. A plain beam that sits on padstones is quick to make; a goalpost frame with bolted connections, or a beam with several steel-to-steel connections, takes longer.
- Simple bearing beams: least fabrication
- Goalpost and box frames: welded or bolted corners, baseplates
- Splices: needed when access is tight - adds plates, bolts and time
- Fin plates, end plates and cleats for beam-to-beam connections
3. Coatings and fire protection
Internal steel in a dry, heated building is usually shop-primed. External or exposed steel is normally hot-dip galvanised, sometimes with a powder coat on top. Building control often requires 30 minutes' fire resistance for domestic beams; this is commonly achieved by boxing the steel in fire-rated plasterboard, or by intumescent paint where the steel will be left visible. Galvanising and intumescent coatings add cost and lead time, so it pays to confirm what is actually required.
4. Delivery and access
Steel delivered to an open site with lorry access is straightforward. Central London streets, loading restrictions, narrow side returns and steel that has to be hand-carried through a house all add time - and sometimes require splices or smaller vehicles.
5. Installation
Some clients only need supply - their builder fits the steel. Others want the steel erected for them. Installation price depends on the weight of the pieces, how many lifts are needed, whether props and needles are in place, and access for lifting equipment.
What isn't usually in a steel fabricator's price
- Structural engineer's design and calculations
- Building control or approved inspector fees
- Padstones, propping and making good (usually the builder)
- Party Wall Act notices and surveyor fees
How to keep the cost down
- Send the engineer's drawings and calculations - accurate information means no allowances for the unknown
- Tell us about access early so splices are designed in, not added late
- Only specify galvanising or intumescent where it is genuinely needed
- Combine items (beams, posts, lintels, stair stringers) into one order
The quickest way to a real number is a quotation based on your drawings. We return every quote within 48 hours, itemised so you can see exactly where the money goes.