RSJ Beam Cost UK 2026: Steel Supply, Installation and Total Project Budget
An RSJ beam (rolled steel joist, also called a universal beam or steel beam) is the steel section installed above a new opening when a load-bearing wall is removed. This guide covers the full RSJ beam cost in the UK in 2026: the steel itself, the installation, the structural engineer fee and the making good to so you can budget the complete job before you start. RSJ beam cost varies significantly by span, beam size and property type.
RSJ Beam Cost Summary 2026
| Cost Element | Typical Cost (2026) |
|---|---|
| Structural engineer calculation fee | £245 to £600 |
| RSJ beam supply (steel only) | £80 to £400 |
| Padstones supply | £40 to £120 |
| RSJ installation (builder's labour) | £800 to £2,000 |
| Making good (plaster, floor, ceiling) | £500 to £1,500 |
| Building Control fee | £200 to £500 |
Total typical RSJ beam project cost: £1,800 to £5,000. The range is wide because it depends on the span, the number of floors above, the property type and the finish required.
RSJ Beam Cost: Steel Supply Prices 2026
The RSJ beam is ordered from a steel stockholder based on the structural engineer's specification. Common beam sizes for domestic wall removals and their approximate 2026 supply costs:
| Beam Serial Size | Typical Domestic Use | Supply Cost Approx |
|---|---|---|
| 127x76 UB | Very small openings, up to 1.8m span | £60 to £100 |
| 152x89 UB | Small openings, 2 to 3m span | £80 to £150 |
| 178x102 UB | Medium openings, 3 to 4m span | £110 to £200 |
| 203x102 UB | Medium-large openings, 4 to 5m span | £150 to £260 |
| 254x102 UB | Large openings, 5 to 6m span | £200 to £350 |
| 305x102 UB | Very large openings, bi-fold spans | £260 to £420 |
These are guide prices for standard lengths cut to size. Prices vary with steel market conditions, supplier location and whether any drilling or shot-blasting is required. Your builder orders the beam from the structural engineer's specification to they will know local suppliers and current pricing.
RSJ Beam Cost: Installation and Builder's Labour
Installing an RSJ beam involves propping the floor above before the wall is removed, removing the masonry, positioning the beam, setting the padstones at each bearing end, and removing the temporary propping once the beam is carrying the load. This is typically a two-person job taking one to two days for a standard domestic installation.
Typical RSJ installation labour costs in 2026
- Simple opening in modern cavity brick wall: £800 to £1,200
- Solid brick wall (Victorian/Edwardian terrace): £1,000 to £1,600
- Large opening or bi-fold door span: £1,400 to £2,000
- London and South East: add approximately 25 to 40%
What affects the installation cost
Solid brick walls (common in pre-1920 properties) take longer to remove than cavity brick or lightweight block. Very wide openings require more substantial propping and may need a crane or Tirfor to position the beam. Beams in party walls (shared with a neighbour) require Party Wall Agreement before work starts and may need additional coordination. Tight access to the site, particularly in Victorian terraces with no side passage, increases labour time.
RSJ Beam Cost: Structural Engineer Fee
A structural engineer designs the correct RSJ beam size, specifies the padstones, checks the masonry below, and produces the Building Control calculation pack. This is a legal requirement for any load-bearing wall removal to Building Control will not approve the work without it.
The structural engineer fee for a single RSJ beam calculation starts from £245 and is usually ready the next working day. For full details of what the fee covers and how it varies by project type: load bearing wall removal cost guide and structural engineer cost guide.
The calculation pack includes the beam specification your builder uses to order the steel. This is why the engineer's work comes first to you cannot order the correct beam until the calculation is done.
RSJ Beam Cost: Padstones
Padstones are the precast concrete or engineering brick bearing blocks that sit under each end of the RSJ beam, spreading the concentrated point load from the beam end across a larger area of masonry. Every RSJ installation requires padstones, and their size is specified by the structural engineer based on the load and the masonry bearing capacity below.
Standard precast concrete padstones cost £20 to £60 each depending on size, from builders' merchants. A typical wall removal uses two padstones (one at each end of the beam). The padstone specification is included in the structural engineer's calculation pack. See our full guide: padstone design for masonry.
RSJ Beam Cost FAQ
How much does an RSJ beam cost to supply and fit?
The total cost to supply and fit an RSJ beam in a domestic wall removal in 2026 is typically £1,800 to £4,500, including the structural engineer fee, the steel, the padstones, the builder's installation labour, making good and Building Control. The steel beam itself typically costs £80 to £400 depending on size.
Can a builder specify the RSJ size without an engineer?
No. Building Control will not accept a builder's estimate of beam size. A structural engineer must calculate the correct size based on the span, loads and masonry conditions. See our guide to load bearing wall removal for the full process.
How long does RSJ installation take?
The installation itself typically takes one to two days on site. Before that, you need the structural engineer's calculations (24 to 72 hours for a single beam), Building Control approval (obtained in advance under Full Plans), and time to order and deliver the steel (usually three to five working days from a stockholder).
Does the RSJ beam need to be painted or treated?
If the beam will be exposed (as a feature in an open-plan space), it is typically shot-blasted and painted. If it will be boxed in with plasterboard, no surface treatment is needed. The structural engineer's specification includes the beam grade but not the finish to that is a decision for you and your builder.