When undertaking structural work on your home, such as removing walls or adding extensions, you’ll often need to install an RSJ (Rolled Steel Joist). RSJs, also known as steel beams or I-beams, are essential for supporting the weight of the structure above, ensuring the building remains safe and stable. But how much does an RSJ cost in the UK?
In this guide, we’ll explore the cost of RSJs, the factors that affect the price, and what you need to consider when using them in your home renovation project.
1. What is an RSJ?
An RSJ (Rolled Steel Joist) is a type of steel beam used in construction to support loads. It is commonly used in projects like:
- Knocking down internal walls to create open-plan spaces.
- Supporting loft conversions or new floors.
- Adding extensions or conservatories.
RSJs are designed to handle heavy loads and provide structural support to your home. They come in various sizes, and the cost will depend on the size and complexity of your project.
2. How Much Does an RSJ Cost in the UK?
The cost of an RSJ can vary depending on factors such as the size, type of steel, and installation requirements. Typically, an RSJ costs between £200 and £950, depending on its dimensions and load-bearing capacity. Here’s a breakdown of average RSJ costs:
- Small RSJ (up to 2 metres): £200 - £300.
- Medium RSJ (2 - 4 metres): £300 - £600.
- Large RSJ (4 - 6 metres): £600 - £950.
These prices are for the steel beam itself and don’t include installation costs. If your project requires custom-sized or specialised beams, prices can be higher.
3. Factors Affecting the Cost of RSJs
The cost of an RSJ can be influenced by several factors, including:
a) Size and Length of the Beam
The longer and heavier the RSJ, the more expensive it will be. RSJs come in different sizes to suit the load they need to support. For example, a large RSJ supporting a second floor will cost significantly more than a small one used to support a single wall.
- Smaller beams (1 - 2 metres): £200 - £300.
- Medium beams (3 - 4 metres): £400 - £600.
- Larger beams (5 - 6 metres or more): £600 - £950+.
b) Load-Bearing Capacity
RSJs must be selected based on the weight they need to support. If the beam is required to hold up a heavy load, such as a second floor or roof, a stronger and thicker beam will be necessary. Stronger beams with higher load-bearing capacities tend to be more expensive.
c) Type of Steel
RSJs can be made from different types of steel, with some types being more expensive due to their strength or corrosion resistance. For most domestic projects, a standard steel beam is sufficient, but some situations may require more specialised beams, such as:
- Galvanised steel: Steel coated with zinc to prevent corrosion, which is more expensive but necessary in environments where moisture is a concern.
- Fire-resistant steel: Often used in commercial buildings or homes requiring high fire safety standards, this steel is more costly.
d) Labour and Installation Costs
In addition to the cost of the RSJ itself, you’ll need to factor in labour costs for installation. Installing an RSJ is not a DIY project — it requires skilled professionals such as builders, structural engineers, and sometimes even specialists like crane operators for larger beams.
Labour costs for RSJ installation typically range from £500 to £1,500, depending on the complexity of the job. This includes the cost of propping up the existing structure, inserting the RSJ, and ensuring everything is safe and secure.
4. Do You Need a Structural Engineer?
When installing an RSJ, you will almost certainly need a structural engineer to calculate the correct size and type of beam required for your project. The structural engineer will assess the load the RSJ needs to support and ensure the beam meets building regulations.
The cost of hiring a structural engineer typically ranges from £300 to £1,000, depending on the complexity of the project. They will produce detailed drawings and calculations, which you’ll need to submit for building regulations approval.
5. Building Regulations and RSJ Installation
In the UK, the installation of an RSJ is subject to building regulations. This is because any structural work on your property needs to be inspected and approved to ensure it is safe and complies with local building codes. You’ll need to apply for approval through your local authority or hire a private building inspector.
The cost of building regulations approval is usually between £200 and £500, and it’s an essential part of the process. The inspector will assess the installation to make sure the RSJ has been fitted correctly and is structurally sound.
6. RSJ Installation Process
The installation of an RSJ typically follows these steps:
- Site Survey: A structural engineer assesses the property and specifies the size and type of RSJ required.
- Propping Up the Structure: Before the wall can be removed, temporary supports are installed to hold up the structure above.
- Removing the Wall: The builders carefully remove the existing wall or section that the RSJ will replace.
- Inserting the RSJ: The RSJ is lifted into place and secured. For larger beams, a crane or specialist equipment may be required.
- Building Regulations Inspection: The building inspector assesses the work to ensure it meets safety standards.
- Finishing Work: Once the RSJ is in place, the walls are made good, and any additional plastering or decorating is completed.
The process can take a few days, depending on the size and complexity of the job.
7. RSJ Cost Breakdown Example
To give you a clearer idea of how much a typical RSJ installation might cost, here’s an example:
- RSJ Beam (4m, medium load): £500
- Structural Engineer Fees: £400
- Labour Costs: £1,000
- Building Regulations Approval: £300
- Total Cost: £2,200
This example is for a standard RSJ installation, and costs could vary depending on factors like your location, the complexity of the work, and the specific requirements of your project.
8. Do You Always Need an RSJ for Wall Removal?
Not every wall removal project will require an RSJ. If the wall is non-load-bearing, you won’t need a structural beam. However, it’s crucial to get a professional assessment before proceeding with any structural changes. A structural engineer or builder can advise whether the wall you plan to remove is load-bearing and whether an RSJ is required.
9. Conclusion: How Much Does an RSJ Cost?
In summary, the cost of an RSJ in the UK depends on several factors, including the size, type of steel, and installation complexity. For most domestic projects, you can expect to pay between £200 and £950 for the RSJ itself, with total costs (including labour, structural engineer fees, and building regulations) typically ranging from £1,500 to £3,500.
