Built-up I-sections have been extensively used whenever standard I-sections could not satisfy the moment carrying and shear capacities required. In these built up sections it has been common practice to use more steel in webs rather flanges. In this paper it has been proposed to study the behaviour of encased cold-formed corrugated web beam. In these built up sections it common practice to use more steel in webs rather flanges. This results in uneconomical sections as steel is an expensive material. So introducing corrugated profile in web reduced the web instability and also the need for providing transverse stiffeners. But, even after corrugated webs and lateral stiffeners in unison effects like lateral torsional buckling were observed. Thus measures other than providing conventional transverse stiffeners and corrugated webs were to be found. Encasing the corrugated web of steel beam could improve the resistance to transverse deflections.