RSJ Calculations in Kent: What You Need to Know

If you’re removing a wall or opening up your home, you’ll almost certainly need an RSJ (steel beam).

But before any steel goes in, you’ll need proper structural calculations.

What is an RSJ?

An RSJ (Rolled Steel Joist) is a structural beam used to support loads when:

• Removing internal walls
• Creating open-plan spaces
• Supporting extensions or loft conversions

It ensures the weight of the structure above is safely redistributed.

Why calculations are essential

You can’t guess steel sizes.

Structural calculations ensure:

• The beam is strong enough
• Deflection is controlled (no sagging)
• Loads are safely transferred to supports
• The design complies with Building Regulations

This is a requirement across all Kent authorities, including Swale, Dartford and Sevenoaks.

What’s included in RSJ calculations?

A typical package includes:

• Beam size and specification
• Load assessments
• Padstone design
• Connection details (where required)
• Supporting sketches

This gives your builder everything needed to install the steel correctly.

Common mistakes to avoid

• Installing steel without calculations
• Using “standard sizes” without checking loads
• Not allowing for padstones or proper bearings
• Poor coordination between design and structure

These can all lead to delays, extra costs, or compliance issues.

Simple, done properly

We provide fast, in-house RSJ calculations across Kent, ensuring your project is:

• Fully compliant
• Easy to build
• Ready for Building Control approval

Send over your drawings and we’ll get your steel design turned around quickly.