The influence of sheeting made by sandwich panels on the lateral-torsional buckling resistance of hot rolled purlin was studied in this paper. The actual shear and torsional stiffness as well as resistance of connections between sandwich panel and purlins were considered in analysis. Parameters of these factors were determined using the finite element method, as well as by own experimental tests. Simple models with beam elements were used in LBA analysis to calculate the critical moments of the purlins. Advanced models with GMNIA analysis using shell elements was performed to simulate the behaviour of the purlins stabilized by sandwich panels. The results show that the stiffness of sheeting made by sandwich panels is insufficient to ensure the full protection of purlin against lateral-torsional buckling. The connections resistance also limited the ability of purlins stabilisation. Nevertheless including sandwich panels in purlin stability analysis results in a significant increase in their LTB resistance.