This study investigated the structural behaviour of new building system that is completely fabricated from thin cladding. This new system developed by Modern Gauge Australia (MGA) significantly reduces the quantity of steel as it has neither conventional frame nor purlins/girts. As a part of this study full scale tests were performed where cross wind, long wind and live load cases were considered. Finite element models were also developed and their analysis results agreed with the test findings. Since it was found that the MGA test structure is not suitable for an ultimate design wind speed of 41m/s, a new cold-formed steel building system was developed and its details are presented in this thesis. Based on finite element modelling it was proved that this new building system can withstand a wind speed of 50.4 m/s and was approximately 250% stiffer than the original MGA building system.