Planning to remove a load-bearing wall or create an open-plan kitchen? Knowing the full RSJ installation cost can help you budget before work begins. A typical residential RSJ wall-opening project costs around £1,800–£5,000 in the UK in 2026. This broader budget can include the steel beam, structural calculations, wall removal, installation, Building Control fees and basic finishing. If you only need the beam supplied and fitted, published guide prices are around £500–£1,700, excluding other structural and building work.
The difference matters because a low beam-fitting quote may not cover everything needed to complete your project.
How Much Does an RSJ Cost in the UK?
An RSJ, or rolled steel joist, is a structural steel beam used to support loads above an opening. The term is also commonly used for modern universal beams. The table below separates basic steelwork costs from complete structural opening projects.
| Project or service | Estimated UK cost |
| Steel beam supply only | £200–£950 |
| Basic RSJ supply and fitting | £500–£1,700 |
| Standard 2–3 metre wall-opening project | £1,800–£3,500 |
| Larger 4–5 metre wall-opening project | £2,500–£5,000+ |
| Complex openings or multiple beams | £5,000–£12,000+ |
These are indicative 2026 budgeting ranges, not fixed prices. Basic fitting estimates generally exclude demolition, engineering fees and finishing. Full-project figures describe broader work, although inclusions still vary. For example, installing a beam into a prepared opening is different from removing an entire supporting wall and restoring the surrounding room. The Checkatrade RSJ cost guide provides further information about current steel beam supply and fitting prices.
RSJ Installation Cost Breakdown
A complete RSJ project involves several expenses beyond purchasing the steel.
| Cost item | Indicative UK price |
| Steel beam supply | £200–£950 |
| Structural engineer calculations | £250–£700 |
| Builder’s labour and associated installation work | £800–£2,500 |
| Building Control fees | £200–£500 |
| Basic padstone materials and support equipment | £40–£300 |
| Plastering, ceiling repairs and making good | £300–£1,500 |
These figures are approximate allowances from published UK pricing guides. They should not simply be added together because some quotations already include several items. Temporary support labour, lifting arrangements or complicated masonry work may also cost more than the basic allowances suggest.
Steel Beam Supply Cost
Steel beam prices depend on length, weight, section size and fabrication requirements. Published guide prices commonly range from approximately £2.50–£4.50 per kilogram. However, supplier charges can differ depending on the steel specification. A heavier beam usually costs more to purchase and transport. Cutting, drilling, welded connections and delivery can add further charges.
This explains why the RSJ beam cost per metre is not fixed. Two beams of the same length may have very different weights and prices.
Structural Engineer Calculation Fees
Structural calculations for a straightforward residential beam may cost approximately £250–£700. The fee depends on the design complexity, available drawings and whether site inspections or additional structural checks are needed. A simple beam calculation is generally less involved than designing an opening requiring columns, connections or additional supporting work.
Check whether your engineer’s quotation includes drawings suitable for the builder and Building Control submission.
Builder’s Labour and Installation
Installation work may include preparing the opening, temporarily supporting the building, positioning the beam and completing the required connections. A long or heavy beam may require additional workers or mechanical lifting equipment. Builder’s labour and associated installation work can cost approximately £800–£2,500 for typical residential alterations.
The quotation should state whether this allowance includes wall removal and temporary propping.
Building Control and Finishing Costs
Removing or altering a load-bearing wall in England normally requires Building Regulations approval. Building Control fees vary between authorities and application routes. An initial allowance of £200–£500 may be useful, but local charges must be checked. After installation, the steel beam may require fire protection.
For typical domestic situations, steelwork normally needs suitable fire resistance, often achieved using properly specified plasterboard protection. The exact requirements depend on the building and approved design. Plastering, boxing-in the beam, repairing ceilings and decorating can add to the finishing budget.
How Do RSJ Costs Change for 3, 4 and 5 Metre Openings?
The size of an opening affects the steel section and installation requirements.
| Opening size | Typical project considerations |
| 3 metres | Often suitable for a kitchen-diner knock-through, subject to structural design |
| 4 metres | May require heavier steel and more demanding handling arrangements |
| 5 metres | May involve substantial loads, more complex supports or specialist lifting |
A longer opening does not automatically mean a particular steel beam is required. For example, a 3 metre beam supporting masonry and several floors may need a heavier section than a longer beam carrying lighter loads. Likewise, a 5 metre opening might require additional columns or steel connections, depending on the existing structure.
The final steel section must be selected through appropriate structural calculations, not beam length alone.
What Affects the Total Cost of Installing an RSJ?
Several factors determine how much a complete RSJ installation project costs.
- Wall construction: Removing solid brickwork can involve different labour and support requirements from altering a cavity wall.
- Structural loads: Beams supporting additional floors, masonry or roof loads may require stronger steel sections and supporting details.
- Property access: Narrow hallways, restricted entrances and upper-floor installations can make moving steelwork more difficult.
- Temporary propping: The building must remain safely supported while structural work takes place. Complicated support arrangements increase labour and equipment costs.
- Existing services: Electrical cables, plumbing or gas pipes may need relocating before the beam is fitted.
- Supporting masonry: Existing walls may require padstones, strengthened bearings or additional structural supports.
Labour rates also vary across the UK. Projects in London and the South East can cost more, particularly where site access is difficult. There is no reliable fixed regional percentage that applies to every installation.
Does the RSJ Installation Quote Include Wall Removal?
Not always. Some builders quote for fitting the steel into an opening that has already been prepared. Others provide a complete price covering the wall removal, beam installation and finishing work. Before accepting a quotation, check whether the following are included:
- Steel beam supply, fabrication and delivery.
- Structural engineer calculations and drawings.
- Temporary propping and wall removal.
- Beam bearings, padstones and connections.
- Building Control application and inspection fees.
- Utility alterations and waste disposal.
- Fire protection, plastering and making good.
- VAT and any additional charges.
Confirm whether VAT is included in the quoted price. A quotation excluding VAT can be significantly different from the final amount payable when VAT applies. Also check whether decorative finishing includes painting or only basic plaster repairs. Ask the builder to identify exclusions in writing. When comparing contractors, make sure each quotation covers the same engineering drawings and scope of work.
Do You Need a Structural Engineer Before Installing an RSJ?
A load-bearing wall cannot simply be replaced with an uncalculated steel beam. The replacement structure must safely support the loads previously carried by the wall. For most residential load-bearing alterations, a structural engineer prepares calculations and suitable design details.
The documents may specify the steel section, required bearings, connections and supporting masonry requirements. These details help the builder price the work accurately and provide technical information for Building Control. The engineer’s design service and the builder’s installation work are separate responsibilities unless agreed otherwise.
For further technical guidance, see the Planning Portal information on load-bearing walls.
Frequently Asked Questions
Is VAT Included in RSJ Installation Prices?
Not necessarily. Some contractors show prices excluding VAT, while others provide VAT-inclusive totals. Always confirm the final amount payable before accepting a quotation.
Is It Cheaper to Install an RSJ Without Removing the Whole Wall?
It can be, because retaining part of the wall may reduce demolition and finishing work. However, the saving depends on the structural design, required supports and installation access.
Why Do RSJ Installation Quotes Vary So Much?
Quotations can cover different amounts of work. One contractor may price beam fitting only, while another includes demolition, propping, waste removal and finishing. Compare the written scope before judging the price.
Final Thoughts
For a typical UK residential project, allow approximately £1,800–£5,000 for a complete RSJ wall-opening job, with more complex work costing extra. An appropriate structural design and detailed builder quotations will provide a more reliable project budget. If you’re planning a structural opening in London, South Harrow, Slough or surrounding areas, RG Engineers can help with structural engineering advice and calculations for your project.
