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How to Guide for RSJ Beam Installation


This guide focuses on the price of installing an RSJ beam in the UK. First, we look at the average cost of material, labour, and other necessary things to install an RSJ beam. We will then highlight the factors that affect the price of an RSJ beam and finally, we will explain why RSJ installation should not be seen as a DIY task.

A Rolled Steel Joist (RSJ) is a length of steel commonly used in the building industry to replace a load-bearing wall with a steel beam. RSJs have a unique profile and shape that make them suitable for load-bearing use. When constructing a new home or making structural changes to an existing one, especially when removing a load-bearing wall, installing an RSJ is a necessary step. 

Rolled Steel Joist—RSJ—is an integral part of a structure, providing structural support for new buildings and extensions. The RSJ can also replace an existing load-bearing wall if one is being removed.

How much is an RSJ?

It costs £200 for a single RSJ beam (approximately 1m and up to 46kg/m) and £950 for a much larger RSJ (around 5m and up to 46kg/m).

Your location, access to your property, the required beam size, and whether or not any utilities need to be relocated will all impact the amount of installing an RSJ. To have an RSJ installed, a homeowner in the UK can expect to pay anywhere from £1,500 to £2,450 on average. This includes the cost of a structural engineer, building control approval, hiring a skip, and all the materials and labour needed.

The reason for the RSJ installation will determine the type of work that is carried out to install the RSJ. For instance, you may choose to remove an internal wall in your home to make a room feel larger. It may also be that you want to have an extension added to your property. Depending on the project you want to do, there are different types and sizes of RSJ beams with varying prices.

A good deal on an RSJ can be found for less than £200 per metre, but you should avoid buying the lowest-priced model available. Higher-quality units can be more expensive. As the number of units required increases, so does the job’s overall cost. Additional components will be necessary to ensure that the joists can support the load. These will vary depending on the type of wall being removed.

As an example, RSJ fixture costs for a universal beam are summarized in the table below.

Size of RSJ

Estimated Supply

Estimated Labour

Time Estimated

Estimated Total

1 metre RSJ (universal beam)
£50-£200 inc VAT£400

1-3 days


4 metre RSJ (universal beam)

£150-£300 inc VAT


1-3 days


6 metre RSJ (universal beam)

£180-£500 inc VAT


1-3 days


Factors affecting RSJ costs

It’s important to know that the total cost of RSJ installation varies from project to project, so it’s essential that a homeowner consider the factors that affect the price of RSJ before starting the project. Following are some of the factors that affect the amount of RSJ:


The steel beam’s size is unquestionably a major determining factor in the final cost. The more material that goes into making a larger RSJ beam, the more expensive it will be. An RSJ beam price, on average, between £50 and £200 per meter.

Longer RSJ beams necessitate a heavier beam to safely support the weight assigned to that particular beam length. The greater the weight of an RSJ beam, the greater the amount of steel that went into its construction. To lift and install the beam, the RSJ may also require some mechanical equipment, which will increase the supply and labour costs.

Ease of access

The amount of your RSJ fixture may be influenced by how easy it is to get to your work site. Restricted parking for tradesmen’s vehicles, complicated delivery access, and awkward skip delivery can add to the budget. The cost will vary depending on how easily your house and room can be reached. RSJ movement can be extremely difficult, even if it is only a short distance.

Skip hire

When a load-bearing wall is removed to install an RSJ, a lot of waste is generated. As a result, renting a skip will be required to get rid of any trash. The weekly price of a skip rental ranges from £200 to £300.

Structural engineer fees

A do-it-yourselfer should not attempt an RSJ beam installation project. A structural engineer and a qualified and experienced builder will be required to come to the property and provide input on the structural impacts, to ensure that the property meets Building Regulations.

A structural engineer will perform calculations to determine how much support is needed to support the weight of your home and what steps need to be taken to ensure the job is done safely. To install the correct RSJ, they’ll communicate with the builder to share information.

To remove a load-bearing wall, an engineer will charge around £200-£300 for their time and expertise, depending on how big the project is. Remember that if you want to build an addition or a loft conversion, these are much larger projects, and you should expect to pay a structural engineer much more for their services.


Unfortunately, the process of installing an RSJ is a complete pain in the neck. Even the most experienced contractors will have to cause some damage to your home to remove a load-bearing wall and then install an RSJ safely and correctly. The RSJ may require some replastering and redecorating after installing it to bring the room back to a presentable level. For the most part, this is to be expected with RSJ projects.

Some builders will include replastering the damaged walls in their quotes, but you may also need to hire a different contractor to come in and plaster the walls for you. Wall or ceiling plastering can be anywhere from £600 to $1,000, depending on the size of the space.

Ask the builder about what they have included and what they have not included in their quote so you can determine whether or not you need to budget for things like final plastering and decorating prices.

Painting and Decorating

A painter and decorator will be needed after the RSJ installation is complete with fixing any damage done to the surrounding walls by the installation, so be prepared for that as well. To avoid leaving your property in poor condition after an RSJ installation, you should prepare yourself by painting and decorating or hiring a professional painter and decorator.

For painting or decorating, you can expect to pay around £160 a day on average. However, properties in London will have higher prices than those in other parts of the UK.

RSJ installation is not a DIY project

Because structural engineers must perform the calculations to determine the level of support required, installing an RSJ should never be attempted on a do-it-yourself basis. To comply with current building codes, RSJs must be installed on load-bearing walls to support the weight of any structure built on top of them. As a result, you must involve a structural engineer and a builder in your calculations and plans for the RSJ installation. Another thing to keep in mind is the amount of obtaining approval from Building Control.

When installing an RSJ, it will be necessary to involve a structural engineer because building regulation approval is required. A highly qualified and experienced builder must install this unit. There will be serious consequences—such as injuries and fatalities—if there are mistakes and defects when the RSJ beam is installed.

Attempting to cut corners when embarking on an RSJ installation project is highly discouraged. RSJs can cause serious injury or death to building occupants when improperly installed. Additionally, you’ll avoid paying fines for violating building code requirements altogether.

Get multiple quotes from builders and structural engineers, so you know what to expect. Also, make sure you know all the amounts associated with this type of installation and have budgeted for them in your overall project costs.

Make sure you compare quotes from reputable and qualified builders to find the best fit for your installation of RSJ steel beams before deciding which to work with.

Note: The amounts given in this guide are estimates, they may vary significantly. Use the figures as a starting place for your research. 

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