The RSJ steel beam cost in the UK is typically £200–£1,000 for the steel alone, and around £2,000–£5,000 for a complete structural opening once you include the structural engineer, installation, Building Control, and making good. Longer spans, heavier loads, difficult access, multiple beams and complex alterations can push the total considerably higher.
Opening up a kitchen, removing a dividing wall or creating an open-plan living area can completely change how a home feels. But when the wall you are removing carries the weight of floors, roof structures or masonry above, the job becomes a structural alteration rather than a simple demolition.
That is where an RSJ steel beam comes in. The beam transfers the load previously carried by the wall to suitable supports at each end, allowing a new opening to be created safely.
For homeowners planning a wider renovation, structural work is often only one element of the project. Tacman Developers’ home refurbishment services can be useful when a knock-through forms part of a larger renovation rather than being treated as an isolated job.
- Steel beam only: about £200–£1,000 (roughly £50–£120 per metre for a universal beam, depending on weight and size)
- Complete single-beam knock-through: about £2,000–£5,000 including engineer, labour, Building Control and making good
- Complex jobs (double beams, chimney breasts, several floors above, restricted access): often more than £5,000
What Does an RSJ Do and When Does a Wall Need One?
An RSJ is used to support loads when a load-bearing wall is partly or completely removed. The beam transfers those loads to suitable supports, such as masonry piers, posts or padstones, allowing a wider opening to be formed without compromising the structure.
The term RSJ (rolled steel joist) is still widely used by homeowners and builders. Modern projects, however, usually specify a Universal Beam (UB) or another engineered steel section, so the two terms are often used interchangeably in everyday conversation.
The correct steel cannot be selected simply by measuring the opening. A structural engineer needs to assess what is being supported above it, including floor joists, roof loads, masonry, chimney structures and potentially another storey. For example, a 3-metre opening in a single-storey extension may have a very different structural requirement from a 3-metre opening in a two-storey house supporting upper-floor masonry.
RSJ Steel Beam Cost UK 2026: Supply and Installation
For 2026, the steel beam itself may cost a few hundred pounds, while the complete installation is considerably more expensive because it includes engineering, temporary support, lifting, bearings, labour and finishing.
| Cost element | Typical 2026 budget |
| Steel beam (RSJ / UB) supply | £200–£1,000 |
| Structural engineer | £250–£750 |
| Padstones and bearings | £50–£300 |
| Installation labour, including propping | £750–£2,000 |
| Building Control | £150–£500 |
| Making good (plastering, boxing-in, decorating) | £300–£1,500 |
| Typical overall project | £2,000–£5,000 |
These are indicative figures, not a quotation. The overall total is not simply the sum of the highest or lowest figures: most single-beam jobs land towards the middle of each range. Prices are also generally higher in London and the South East, and you should check whether any quotation includes VAT.
Published cost guides vary because they measure different things. Some include only the beam and labour, while others include the engineer, Building Control and making good. For example, Checkatrade gives an example of a 5-metre beam of up to 46kg per metre costing about £950 in materials and £750 to install. Other 2026 guides put a standard installed beam in a door-width opening at roughly £1,200–£2,500, and a load-bearing wall removal with a beam at £1,750–£4,000 before engineer and Building Control fees.
RSJ cost per metre
Steel beams are priced by weight, so length is only part of the story. Typical supply costs are around £50–£120 per metre for a universal beam, with merchant rates averaging roughly £3.50 per kilogram. A simple steel lintel for a smaller opening costs less, at around £16–£60 per metre.
As an illustration only: a 4-metre 254 x 146 x 31 universal beam weighs about 124kg (31kg per metre). At £3.50 per kilogram, that is roughly £430 for the steel, before cutting, delivery, VAT or any fabrication such as plates or drilling. The engineer decides the actual size, so never price a job from a beam size you have found online.
Typical cost by type of job
| Job | Indicative installed cost |
| Single beam over a door-width opening | £1,200–£2,500 |
| Load-bearing wall removal with a single beam | £2,000–£5,000 (all-in, including engineer and Building Control) |
| Larger opening, double beam or steel goalpost frame | £5,000 and above |
What Makes an RSJ More Expensive?
The beam’s length is only one factor. The final cost can increase when:
- The opening is particularly wide.
- Several floors are supported above.
- A chimney breast or other heavy structure is involved.
- The beam is unusually large or heavy.
- Access to the property is restricted.
- Temporary propping is complicated.
- New steel posts or goalpost frames are required.
- Foundations or supporting walls need strengthening.
- Plumbing or electrical services have to be relocated.
- Extensive plastering and decoration are required afterwards.
A simple kitchen knock-through may therefore cost considerably less than a large structural opening involving multiple steels and additional supports. A common surprise is that plastering, boxing-in, fire protection and decorating can cost as much as the structural work itself, so always price the whole job rather than just the beam.
Steel Beam vs Other Options
Steel is the most common solution for domestic knock-throughs because it is strong and relatively slim, but it is not the only one. Depending on the opening and the loads, an engineer might specify a timber or engineered timber beam, a reinforced concrete beam or lintel, or a steel lintel for smaller openings. Exposed timber beams need a calculation to show how much fire resistance they have, and the structural design remains the same regardless of the material: the engineer decides, not the builder or the merchant.
Structural Engineer Calculations: Why They Are Non-Negotiable
A structural engineer determines the appropriate steel size, loading, bearing requirements and support arrangement. This matters because the correct beam depends on the actual structure above it, not simply the width of the proposed opening. This is one area where homeowners should never try to save money by guessing.
The engineer normally assesses the existing structure and calculates the loads the beam must support. The resulting design may specify the steel section, length, bearing requirements, padstones and other structural details, and it gives your builder and Building Control a clear specification to work from.
The Government’s Approved Document A: Structure provides guidance on the structural requirements for building work in England, including walls, floors, roofs, foundations and chimneys. Choose a suitably qualified engineer: for example, a chartered structural engineer, such as a member of the Institution of Structural Engineers, who holds professional indemnity insurance.
Why the engineer should be involved before ordering steel
Ordering a beam first and asking an engineer to approve it afterwards is the wrong approach. The engineer needs to establish what the beam must carry before the steel section is specified. If the beam is undersized, the structure may not perform as required. If it is oversized, you could pay more for steel and installation than necessary. A professional structural design therefore protects both safety and budget.
Load-Bearing Wall Checks: How to Tell Before You Commit
You cannot reliably confirm that a wall is non-load-bearing by looking at its thickness or position. The structure above, floor direction, roof arrangement and original construction all need to be considered, so professional assessment is essential before any demolition.
Some clues suggest a wall may be structural. A wall is more likely to carry load if:
- Floor joists bear onto it.
- Another wall sits directly above it.
- It supports part of the roof structure.
- It aligns with structural walls elsewhere in the property.
- It forms part of the original structural layout.
- A beam supporting a former chimney stack rests on it.
However, these clues are not enough to approve demolition. Older homes can contain previous alterations, unusual construction and hidden structural arrangements. A wall that looks like a simple partition may have an important structural function, which is particularly relevant in older UK properties where earlier renovations may have altered the original load paths.
If the knock-through is part of a complete property transformation, Tacman’s full home renovation services can coordinate the structural work with kitchens, bathrooms, flooring, electrics and other refurbishment.
Bearings, Padstones and Fire Protection
Two details often catch homeowners out because they add to the cost.
Bearings and padstones. A beam cannot simply sit on brickwork. According to Planning Portal guidance on load-bearing walls, a new beam should normally have at least 150mm of bearing on each side of the opening, and the wall beneath may need strengthening with padstones to spread the load. The engineer specifies the size.
Fire protection. A steel beam should normally be protected so that it has 30 minutes’ fire resistance. The most common method is two or more layers of properly fixed plasterboard, with the thickness set by the manufacturer’s specification. This is usually why a beam is boxed in, and it should be included in your quotation.
The Knock-Through Process: From Survey to Finished Opening
A professionally managed project generally follows a logical sequence.
- Assess the existing wall. Establish whether the wall carries load and what is above it.
- Structural design. The engineer calculates the required beam and specifies its supports.
- Building Control. The structural alteration is submitted through the appropriate Building Control process before work proceeds.
- Temporary propping. Before the wall is removed, temporary supports such as Acrow props and strongboys, or an appropriate alternative, are installed.
- Beam installation. The wall is opened progressively, suitable bearings are prepared and the steel is installed to the engineer’s design.
- Wall removal and finishing. Once the permanent structure is correct, the remaining wall is removed and the opening made good. Fire protection is added at this stage.
The final stage may include plastering, flooring repairs, electrical relocation, skirting, decorating and kitchen installation.
RSJ for a Kitchen Knock-Through: What Should You Budget?
For a straightforward kitchen or dining-room knock-through, think in terms of the complete structural project, not just the price of the RSJ. A reasonable starting budget is a few thousand pounds, with the final price depending on the opening, supports, services and finishing.
A kitchen knock-through is one of the most common reasons homeowners search for RSJ steel beam cost UK. The attraction is obvious: removing a dividing wall connects the kitchen and dining area, improves natural light and creates a more contemporary layout. But the structural work should ideally be coordinated with the wider kitchen renovation. For example, if a socket, radiator, pipe or kitchen unit sits against the wall being removed, those elements may need to be relocated before the structural work begins.
This is why combining structural alterations with a professionally managed refurbishment often makes more sense than treating the beam as a separate project. If your aim is to modernise the property before a future sale, Tacman Developers’ guide to the top UK renovations that add value to a house offers useful context.
Can You Install an RSJ Yourself?
For a load-bearing wall, DIY installation is not recommended. Structural calculations, temporary support, steel handling and Building Control requirements make this a specialist job where mistakes can have serious safety and financial consequences. Steel beams are heavy, and the most dangerous moment is between opening the wall and the new beam taking the load.
A homeowner may be able to help with non-structural preparation or finishing, but the structural element should be designed and installed by competent professionals. The biggest risk is assuming the beam itself is the difficult part. In reality, safety depends on the whole load path: from the structure above, through the steel and its bearings, into the supporting walls or posts and down to suitable foundations. A correctly designed beam that is installed incorrectly is still a structural problem.
How Long Does an RSJ Installation Take?
A straightforward domestic installation may take from one day to a few days on site, although the overall project takes longer once engineering, Building Control, preparation and making good are included. A realistic programme should allow time for:
- Structural engineer assessment
- Calculations and drawings
- Building Control arrangements
- Steel manufacture and delivery
- Site preparation
- Temporary works
- Installation
- Inspection
- Plastering and making good
If you are planning a wider renovation at the same time, these stages can be integrated into the overall construction programme.
What Should Be Included in an RSJ Quote?
A professional quotation should clearly identify the steel, engineering, labour, temporary support, bearings, Building Control, waste removal and making-good requirements. Comparing quotes on the beam price alone gives a misleading picture of the final cost.
| Item | Why it matters |
| Structural calculations | The beam must match the engineer’s design |
| Steel beam specification | Section, length and grade should match the calculations |
| Delivery | Can be an extra charge for long or heavy steel |
| Temporary propping | Essential for safety during the works |
| Padstones and supports | Needed to spread the load into the walls below |
| Installation labour | Check whether it includes lifting equipment |
| Building Control fees | Check who pays and who arranges inspections |
| Fire protection | Usually plasterboard boxing; often missed in cheaper quotes |
| Waste removal | Brick and rubble disposal can be substantial |
| Plastering and making good | Often a significant part of the cost |
| Electrical and plumbing relocation | Frequently excluded |
| VAT | Should be clearly stated |
A detailed quotation makes it much easier to compare contractors fairly. Also check that your contractor has public liability insurance, can provide references for similar structural work, and will give you a written contract and programme.
Why Professional Installation Matters
An RSJ is not simply a piece of steel placed across an opening. It is part of a carefully engineered structural system.
At Tacman Developers, we approach structural alterations as part of the wider refurbishment rather than as an isolated demolition task. With more than 35 years of experience in design and build, we coordinate the structural opening with the associated building work, finishes and your overall renovation objectives. Tacman Developers Ltd is registered in England (company number 15303945). [ADD: one or two real details from your own projects, for example a typical knock-through you have completed, how you handle engineer and Building Control coordination, or a lesson learned on site, to add first-hand experience.]
Conclusion
Understanding the RSJ steel beam cost UK means looking beyond the price of the steel itself. For a load-bearing wall removal or open-plan conversion, the real project cost includes structural engineering, temporary support, the beam and its bearings, installation, Building Control, fire protection and the finishing work afterwards.
For a straightforward domestic knock-through, a budget of around £2,000–£5,000 is a useful starting point, but larger openings, multiple floors, heavier loads and complex support arrangements can push costs considerably higher.
The most important decision is not choosing the cheapest beam or contractor. It is making sure the structural solution is correctly designed, properly supported and installed in accordance with the relevant requirements.
If you are planning a knock-through, structural opening or wider home refurbishment, Tacman Developers can take your project from planning through to completion. Contact Tacman Developers to discuss your project and get professional guidance.
Frequently Asked Questions
How much does an RSJ steel beam cost in the UK?
The steel beam itself typically costs from around £200 to £1,000, depending on its size and specification. A complete structural opening, including the engineer, installation, Building Control and making good, commonly costs around £2,000–£5,000, with complex projects costing more.
How much does an RSJ cost per metre?
Supply costs are typically around £50–£120 per metre for a universal beam, but the weight of the section matters as much as the length. The engineer’s design determines the size, so the price per metre is only a rough guide.
How much does a 4-metre RSJ cost?
The steel for a 4-metre beam is often a few hundred pounds, depending on the section size. Installation, engineering, Building Control and making good are additional.
Does removing a load-bearing wall require an RSJ?
Not necessarily, but a suitable structural solution is always required. A structural engineer determines whether an RSJ, another steel arrangement or an alternative support system is appropriate.
Do I need a structural engineer for an RSJ?
Yes. Professional structural calculations are essential for determining the correct beam and support arrangement.
Do I need planning permission to remove a load-bearing wall?
Usually not. Internal alterations do not normally need planning permission in England, although listed buildings need listed building consent for significant works. Building Regulations will still normally apply.
Do I need Building Regulations approval for an RSJ?
Normally, yes. Removing a load-bearing wall or forming a structural opening generally falls within Building Regulations requirements, and the exact process depends on where the property is located in the UK.
Can I remove a load-bearing wall myself?
It is not recommended. Removing structural walls involves engineering, temporary support and permanent structural installation, so the work should be carried out by suitably qualified and experienced professionals.
How long does an RSJ installation take?
The physical installation of a straightforward beam may take from a day to several days, but the complete process takes longer because it includes engineering, approvals, preparation and making good.
Does an RSJ need fire protection?
Usually, yes. A steel beam should normally be protected so that it achieves 30 minutes’ fire resistance, most commonly with two or more layers of fixed plasterboard. The specification should be agreed as part of the design and Building Control approval.
Is an RSJ included in a refurbishment quote?
It can be, but check carefully. A quotation should state whether engineering, steel, installation, Building Control, temporary works, fire protection and making good are included.
Is VAT charged on RSJ installation?
Building work on an existing home is normally charged at the standard rate of VAT, but this can vary by circumstances. Always check whether a quotation includes VAT.
Can an RSJ increase the value of my home?
The beam itself does not automatically add value, but the open-plan layout it enables can improve functionality and appeal. The effect on value depends on the property’s location, design and the quality of the overall renovation.
