RSJ Beams & Columns Get your free quote Call us now RSJ Steel Beams Klas are specialists in the supply and installation of RSJ Steel Beams.We hold in stock Rolled Steel Joists (RSJs) in the most in demand sizes and weights.Our RSJs can be supplied in several different finishes such as primer, fire paint, powder-coated etc.As we hold RSJs in stock, we can provide quick delivery to our customers.We have craned mounted lorries so we can deliver door to door, or alternatively door to roof!