The Cost of Rolled Steel Joist (RSJ) Installation

All you need to know about the wall replacement and replacement with rolled steel joist (RSJ) beams, including costs of wall removal, RSJ installation, labour and time frames.

The Cost of Rolled Steel Joist (RSJ) Installation

What the job entails

Installing a rolled steel joist (aka RSJ) is a job that is done when constructing a property or during later structural alterations, most commonly the removal of a load-bearing wall. Installing a rolled steel joist is not usually a standalone job with a single cost, usually it is done as part of another job. Installing an RSJ should not even be attempted without first consulting a structural engineer to do the necessary calculations to determine the correct size of steel beam required for the project. This involvement of a structural engineer will be a requirement to get building regulations approval and the actual installation of the RSJ should be done by an experienced builder as this requires real skill and any mistakes could compromise the structural integrity of the property. In other words, forget cutting corners to save cash and contemplating a DIY job - just pay a fair price for reputable professionals to do the job properly and safely, or potentially face some expensive repairs and safety issues down the line.

Before getting a quote for a rolled steel joist installation, you need to understand that installing an RSJ correctly requires careful calculations by a structural engineer and a skilled builder. In addition, the work will create a great deal of mess which will not only require a lot of cleaning up, but will require some re-plastering and re-decorating once the beam has been installed. The bulk of the work can be handled by an experienced local builder, in fact, some building contractors may also have structural engineers in-house, along with electricians and plumbers so they can handle the complete job from start to finish, with the exception of the final decorating work. This type of work creates a great deal of noise, dust and disruption over several days. So you may want to consider finding alternative accommodation while the work is being carried out.

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The Cost of Rolled Steel Joist (RSJ) Installation

The cost of installing a rolled steel joist will vary depending on your location in the UK, the size of the beam, access to your property and whether any utilities need to be relocated. But typically, a rolled steel joist installation will cost somewhere between £1,600 and £2,500 including the structural engineer, application for building control approval, skip hire, plastering, labour and materials for the installation. Although, usually the quotes you get will be for more than just the rolled steel joist itself and will typically involve removing a wall or other building work. You will sometimes need a quote for the RSJ installation itself if the builder cannot do this part of the job.

One RSJ can cost as little as £200 itself, however higher quality joists will cost more, along with the number required for a project, can increase the cost proportionally. There will also be a requirement for other parts to ensure that the joist is correctly holding the load - this can also vary depending on the circumstances of the wall removal/replacement in question.

Below are some estimated costs of Rolled Steel Joist (RSJ) Installation.

Job Description Avg. Cost Duration
Knock Down Internal Load-bearing Wall and Install 3m Rolled Steel Joist £2,500 1 week approx.
Knock Down Internal Load-bearing Wall and Install 5m Rolled Steel Joist £3,000 1 week approx.
RSJ Supply-Only Cost £55 per metre 1-3 days for delivery
Supply and Fit Only - Average 3m RSJ £1700 1-2 days

Cost Breakdown

Individual costs of installing an average 3m Rolled Steel Joist (RSJ) - Total Cost: £2,500






Waste Removal


No - this will require a structural engineer and/or architect as a minimum to work out the support required. A professional builder is also recommended to do the actual work - when it comes to structural jobs like this forget about DIY. You may be able to do part of the job to cut costs, such as removing waste and redecorating, but the bulk of the work is best left to the experts.
You need to get building regulations approval if you are extending or structurally altering an existing building, so installing a rolled steel joist will almost certainly require building regulations approval, but this is not the same as planning permission, which you may also need. Calculations and plans for any steel beams will need to be provided to the Building Control Officer to gain approval, but reputable and professional builders can help with this. The Building Control Officer will check the calculations and building works comply with all the current building regulations. You can use a Building Control Officer from your local council or you can hire a private sector approved inspector.
Taking down or altering internal walls doesn't normally concern the planning department, unless in a listed building. However, before making any sort of structural alteration to a building a Building Regulations application must be made at the very least and you should always check with the planning department before you plan on any building project in any case as rules and regulations change over time.
In terraced or semi-detached houses where the new steel beam will rest in the party wall that separates you from the neighbour, it's advisable to contact a specialist surveyor to ensure compliance with the relevant party wall legislation. It is likely that you will need some sort of legal agreement with your neighbour before commencing any work on a shared wall.
Some internal walls are fundamental to the structural integrity of the house, whereas others simply divide up the interior space and can be removed without any issues. Internal walls are built of either solid masonry or of lightweight timber stud or metal frames. Generally speaking, stud walls are not load bearing, but this is not always the case. Solid masonry walls are also not always load bearing, some are simple partition walls. A load-bearing wall will support the roof structure, floor joists, upstairs walls or will provide lateral support to tie together the adjoining walls. It's not as easy as some think to identify load bearing wall so it's best to consult a structural engineer or building surveyor before you remove any or alter any internal walls.