If you’re planning major structural work like an extension or removing a load bearing wall, you’ll have to budget for RSJ (Rolled Steel Joints) beams. These steel beams provide the structural support for new builds and extensions – and may be either temporary or a permanent part of your home’s frame.
In addition, these materials are high strength, so adding an RSJ frame can replace the full structural support of a wall – allowing you to safely extend the back wall of your home or merge two rooms without risking structural collapse.
RSJ steel beams normally cost about £200 per metre covered, or £2.50-£5 per kg of steel. Often, those prices go down as you purchase longer lengths – but the costs will typically range between £175 and £200 per metre.
In addition, you can expect to pay about double those costs in labour. This includes structural engineering, installation, plastering, and paint.
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What Are RSJ Steel Beams?
Rolled Steel Joints, I Beams, or H Beams are constructed using a single piece of steel. The steel is cold-rolled into shape – creating an extremely strong piece of metal. This is ideal for supporting walls and floors and replacing the load-bearing capacity of an existing wall.
RSJ Steel Beams are designed for load-bearing or holding up walls. Often, this means they are used to strengthen girders and joists when adding new stories, to replace load-bearing walls, and to support a structure while a new load-bearing wall is being built.
However, RSJ beams are not ideal for multi storey buildings, because they can tear. This means that if there’s a lot of weight or tension on the top, they will shear and may twist. Therefore, RSJs are primarily used in low storey buildings and to support existing builds.
RSJ beams also come in a wide range of different sizes, with different flange sizes, and using terminology like web (thickness) flange (width), and weight. These each impact the load-bearing capacity of the beam.
However, you’ll need a structural engineer on the project, and that engineer will handle these calculations for you.
RSJ Universal Beam Costs*
RSJ beams normally cost about £200 per metre for materials plus an additional £200- £300 for labour costs. However, that can look quite a bit different depending on what you’re doing.
The following chart details some different cost scenarios for these beams. Importantly, the cost per metre includes the joists, flanges, and supports for the beams – meaning it costs more per metre for a small doorway than for a large room support.
| Project | RSJ Beams Cost | Labour Cost |
|---|---|---|
| Doorway | £120-£200 | £250-£350 |
| Double Doorway | £250-£350 | £550-£600 |
| 4M Room | £720-£960 | £650-£900 |
| 5M Room | £900-£1,160 | £650-£950 |
| 6M Room | £1,080-£1,992 | £650-£950 |
Please note these costs are based on quotes at the time of writing in May 2023. Actual costs may vary based on location, thickness/weight of steel, and updates to cost of labour. Use this guide as a starting point for your own research.
6 RSJ Price Influences To Consider
The largest factor influencing the cost of RSJ universal beams is the amount of steel you need. However, other costs like the cost of labour, structural engineering fees, and planning permission can be considerable as well.
1. Size of Build
Most RSJ steel beams are sold by weight. This means you’ll pay a flat-rate per kg rather than a price per metre or a price per m2. However, the “standard” RSJ steel beam used for shoring up extension projects weighs about 19 kg per metre. You can also expect to pay an average of £3.50 per kg. This means you’ll pay an average of £66.50 per metre of material.
That cost allows you to better calculate exactly how much steel you need. For example, if you’re putting in a frame for a doorway, you know that the frame is 2 metres by 80 centimetres. If you need 2 supports and a top, you need 4.80 metres of steel, or £319.20 of materials – before any labour costs.
On the other hand, a double door is close to 2 metres wide – so you need 6 metres of steel. That works out to £399 in materials at the average cost.
And, if you’re putting in a support across the room to replace a load-bearing wall, you could say that you need 2.8 metres to the ceiling supports plus the width of the room, and two supporting joists of .5 metres each.
- 4 Metre Room – £704.90
- 5 Metre Room – £771.40
- 6 Metre Room – £837.90
That also means you pay less per metre of covered space when you switch to a larger room. For example:
- 1 metre of distance – £319.20 per metre
- 2 metres of distance – £200 per metre
- 4 metres of distance – £176 per metre
- 6 metres of distance – £140 per metre
Of course, “average” costs can be misleading. Actual rates can vary a great deal. However, you can always expect that the larger your build area is, the less you’ll pay per metre of distance you cover. However, the cost per weight of steel will almost always be the same.
In addition, if you cover a very large distance, you may need thicker and more durable steel. That may mean the cost goes up.
However, you won’t usually see this until your build project gets to be 8-10 metres wide or more. At the same time, you’ll always have to consult with your structural engineer to see what you need to support the building.
2. Cost of Labour
The cost of labour can be as much or more than the cost of materials. Here, you can expect it to take several days to install an RSJ frame into your home. For example, most frames will take 1-3 days of labour.
Here, you’ll normally have a team of people to handle the work of installing the frame. This includes:
- 2-6 people to safely handle beams. Most weigh 19 kg per metre, meaning you always need at least two people on the job.
- Equipment to lift the beams. Most jobs will include clamps and hoists and if you have a very large frame, you may even have heavy equipment on site. This may be included in the cost of labour but you may also pay a separate fee.
On average, you’ll pay a contractor about £150 per day. However, with more people on the job, this means you’ll pay £300-£900 per day of work.
Luckily, most simple builds will go up within 1 day. However, if you have a complex frame that requires more work, or fewer people on the job, it could take several more days.
3. Delivery
I-beams have to be delivered by truck – which normally means paying £40-£150 in delivery costs.
This cost is typically minimal compared to other costs associated. However, it is something to keep in mind when planning a budget.
4. Structural Engineering Fees
In most cases, you’ll pay an average of £450 in structural engineering fees for your project. However, it’s important to keep in mind that this is for the full project, including drawing up plans for planning permission, the structural engineering of your extension or build, etc.
On average, that works out to about £90 per hour. If your construction contractor has a structural engineer in-house, you may end up paying less. However, you should budget about £90 just for the RSJ build.
In addition, some structural engineers charge a flat-rate per build. This may be a percentage of the total project. It might also be a flat fee like £300. You’ll have to ask to see what you’re paying.
5. Planning Permission & Notification Fees
You’ll always need planning permission for any build that requires RSJ beams to support the structure. This means you’ll have to get a structural engineer to draw up plans and you’ll have to apply for permission 6-8 weeks before the build starts.
Normally, this costs £200 in total fees. However, the initial application fee is £60. Make sure you have your plans drawn up before you apply.
In addition, extensions and removing walls are notifiable work. That means notifying building control after the project is complete. That will cost £170-£690 depending on where you’re at.
However, if your contractor is in the Competent Person’s Register, they can handle the actual work of notifications for you. In addition, they may roll the cost of notifications into your initial quote.
6. Finishing
Most people don’t want to install I-beams in their homes and then leave them. Instead, you’ll usually want to cover and plaster over them, so they look like the rest of the wall. That will cost, and usually about £40 per square metre.
However, the cost of finishing over beams will depend on several factors. For example, if you’re building a beam into a cavity left by an old wall, you can rebuild the new wall over it.
You won’t pay more than you would have with a traditional brick or wood construction. Therefore, these costs can be fairly minimal.
What Are RSJs Used For?
Rolled steel joints are normally used to provide structural support in single storey constructions. This includes new build projects, extensions, and remodelling.
- New Builds – RSJs are more frequently used as a basis for the frame, because they offer significant structural support at a relatively low cost. That’s especially true with buildings that use concrete forms for the walls and floors rather than traditional brickwork construction.
- Replacing Load-Bearing Walls – If you want to expand a room by knocking out a wall, replacing the load-bearing wall with an RSJ frame can allow you to do so safely. Here, the wall is normally removed and replaced with temporary supports. You then add the frame in when the old wall is clear. Then, you plaster and re-cover over the wall.
- Extensions – If you want to extend your home by knocking out the back wall and building into the garden, RSJ frames are the way to go. Not only do the RSJ frames replace the load-bearing back wall, but they also provide the structural support for the new building – even if you’re using traditional brickwork.
- Levelling – If your flooring is uneven or collapsing, removing the existing flooring and replacing it with RSJ beams can solve the issue.
- Removing Chimneys – Chimneys can be quite a bit load bearing. This means you may have to replace them with a beam when you take them out.
In some cases, you can also use RSJ joists to add support to existing frames – although this isn’t always recommended.
Do You Need A Structural Engineer For RSJs?
You always need a structural engineer for any home renovation or remodel that involves removing or changing load-bearing walls. That’s true for two reasons:
- You’ll need a structural engineer to draw up plans for planning permission. This may vary from area to area.
- It’s safer to remove or change load bearing walls following the advice of a structural engineer, so you can ensure the long-term stability of your home
In addition, if you’re building in a flood plain or a similar area with high risk, you’ll be legally required to hire a structural engineer to oversee the project.
Typical RSJ Beams
There are two main types of RSJ steel beams. In most cases, your frame will include both I-beams and H-beams.
I-Beams
I Beams feature a cross-brace at the top and a centre column, creating an “I” shape from the top. The sides taper out towards the ends. These are normally sued for spans of 1-10 metres.
In addition, I-Beams are ideal for supporting walls and columns. This makes them an ideal choice for pillar supports replacing a load-bearing wall.
H-Beams
H-beams are very similar to I-beams but are thicker and have thicker cross-bars. This makes them more resistant to tearing and shearing. Therefore, they can be used for lengths over 10 metres.
In addition, these beams are better suited to supporting floors and roofs – making them the most popular choice for the tops of frames.
However, they are thicker, which means that an H beam of the same size as an I-beam will weigh more, meaning that you’ll pay more for the same length of steel.
Hiring Checklist
Hiring a team to install RSJs in your home is about the same as hiring any other type of general contractor.
You’ll want to compare options, make sure everything you need is included, and ensure ownership of waste materials upfront.
- Part of the competent person’s register
- Uses BS4 (British Standard for Structural Steel Sections) and BSI (British Standards Institution) marked steel
- Workers’ compensation
- Liability insurance
- Workmanship guarantee
- Rust/corrosion guarantees
- Quotes are detailed and compared favourably to alternatives
- As much work as is possible is completed by one contractor
- Reviews/references are favourable
How To Save Money With RSJs
Installing RSJs is always going to be expensive. However, you can save money by:
- Opting for prefab beams, which arrive on-site ready to assemble. This saves you the timeline and difficulty of having a team cut steel to size in or outside your home.
- Ensuring accessibility is an option. The harder it is to get to the area, the more you’ll pay in labour costs. For example, clear out your garden, remove furniture, etc.
- Shop around and compare multiple quotes. Rates can vary quite a bit, even based on what equipment a particular contractor has to hand.
- Shop around for steel beams to reduce delivery rates
Steel Beam Installation Process
Universal beams are used for a wide variety of home projects, including extensions, levelling, support projects, etc. The process of installing them will be slightly different for each.
Levelling Floor
If you’re having flooring issues, steel beams can be used to replace failing construction beams.
- Remove flooring and sub-flooring.
- Build in support for the floor.
- Cut out parts of the frame or remove the full frame.
- Replace the frame with new metal joists and re-level the floor.
- Replace the underfloor and flooring.
- Dispose of waste.
Replacing Load Bearing Wall
If you want to knock out a wall to create a more spacious room, RSJ frames can help you achieve it:
- Build a temporary support scaffold on one side of the wall, to take the weight of the structure off the wall.
- Knock out the existing wall, without damaging the scaffolding.
- Build the new frame into place (weld or bolt) and attach it to the main structure.
- Paint or plaster over the frame.
- Dispose of the waste.
Extensions
RSJ frames are also commonly used to enable extensions. Once the new foundation is poured and cured:
- Build a support scaffolding inside the home to take the weight off the back wall.
- Build an RSJ frame to support the new brickwork/cement walls.
- Knock out the back wall of the structure.
- Build an RSJ frame into the space the wall was in.
- Connect the old and new frames.
- Connect the subfloor to the new subfloor.
- Install H-beams for the roof support and connect these to the frame on the original house.
Loft Conversions
In some cases, you’ll need RSJ beams to support your loft conversion:
- Remove the flooring and underfloor in the loft.
- Reinforce the floor frame with steel beams. This may involve replacing the full floor.
- Replace the underflooring.
In each case, you’ll want to have a structural engineer decide on types of steel, the thickness of steel, and how much metal frame you need to support your project.
Building Regulations & Planning Permissions
Most projects that require RSJ steel beams do not necessarily require planning permission.
For example, you can knock out a load bearing wall without planning permission, unless you live in a listed building. However, you will need a structural engineer or surveyor to help with the project to ensure the ongoing stability of the building.
You also won’t need planning permission for most loft conversions or for small extensions. You will need planning permission if your extension takes up more than half your garden, is visible to a public road, or is more than 4.5 square metres.
On the other hand, any work that requires RSJ beams will require notifying building control. This will mean paying for notifications after finishing the project.
It’s actually optional to have a structural engineer or surveyor on your project. However, it is highly recommended and could prevent damage to the building.
In some cases, your general contractor will be able to provide structural engineering services – so you might not need a separate contract for those services.
Next Steps
RSJ steel beams are extremely useful for shoring up buildings when you’re renovating, changing layouts, extending buildings, or removing walls. Steel is durable enough to replace the full load of a wall, which can give you the freedom to create an open floor plan, turn your loft into a bedroom, shore up shaky flooring, add an extension, etc.
However, RSJ steel beams are not cheap. On average you’ll pay £3.50 per kilogram of steel – or about £66 per metre. In addition, you’ll have to pay for delivery costs, construction, and covering up after the steel, which averages out to a total of about £200 per metre. In addition, if you need long beams installed in a space without good access – you might find that prices can climb even higher.
If you need RSJ steel for your building project, the best place to start is by comparing prices. Use the form at the top of the page to request quotes in your area.