​Using RSJ in Residential Construction: When Do You Need One?

Home renovations can transform the way a property looks and functions, but removing walls or making major structural changes requires careful planning. One of the most common structural solutions used in residential projects is an RSJ (Rolled Steel Joist).
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But when is an RSJ actually required, and why is it so important? Here, we explain using RSJ in residential construction, including when you may need one and the key considerations before work begins.

What Is an RSJ?
An RSJ’s purpose is to support loads from above and safely transfer those loads to suitable supporting points, such as walls or columns.

Steel is widely used in residential construction because it can provide substantial load-bearing capacity while allowing relatively large openings to be created within a building.

An RSJ isn't simply a stronger replacement for a removed wall, however. The correct beam size, span and supporting arrangements must be determined through structural calculations based on the specific property and loads involved.

When Do You Need an RSJ?
You may need an RSJ when a renovation involves removing or altering a load-bearing wall. These walls can support floors, roof structures, walls above or other parts of the building, so removing them without providing suitable structural support can compromise the stability of the property.

Common projects where RSJs may be required include:
Open-Plan Living Spaces
Removing a wall between a kitchen, dining room or living area is a popular way to create an open-plan layout. If the wall is load-bearing, an RSJ may be installed to support the structure above the new opening.
Larger Door Openings
Installing bi-fold or sliding doors often involves creating a much wider opening in an external wall. Depending on the existing construction and loads, a structural steel beam may be needed to support the masonry and structure above.
Loft Conversions
Loft conversions can introduce significant structural changes, including new floor structures and alterations to the roof. Steel beams may be required to support the new loads and create a suitable structural arrangement.
Chimney Breast Removal
Removing a chimney breast can leave masonry or chimney structures above without their original support. Steelwork may be required to safely support the remaining structure.
Extensions
Home extensions frequently involve opening up an existing external wall. Structural steel can be used to bridge the new opening while transferring loads safely to the appropriate supports.

Why You Need a Structural Engineer
Determining whether you need an RSJ should never be based on appearance alone. A wall that looks relatively lightweight may still be carrying important structural loads.

A structural engineer can inspect the proposed alteration, assess the loads involved and design an appropriate beam and supporting arrangement. They can also provide structural calculations and drawings where required for building control approval. 

Temporary support is also an important part of the installation process. During construction, temporary works such as props may be required to support the building while the existing wall is altered and the permanent steel beam is installed.

Get Professional Advice Before Removing a Wall
If you're considering an open-plan renovation, extension, loft conversion or another structural alteration, don't start demolition until you understand what is supporting your property.

Using RSJ in residential construction can provide an effective way of creating larger openings and supporting altered structures, but every project is different. Professional structural assessment and correctly designed steelwork are essential for a safe and compliant renovation.

Speak to a qualified structural engineering company before work begins to ensure your proposed alteration is properly assessed, designed and supported. ELSE helps homeowners in Barking and Dagenham, Hackney, Havering, Newham, Redbridge, Tower Hamlets, Waltham Forest and surrounding areas.