In this paper the experimental characterization of the base-material for a new generation of cold-formed steel beams (MLC Beams) is shown. The special features of such members have required the set-up of an appropriate methodology of study aimed at the evaluation of the imperfections arising from the whole manufacturing process: rolling and cold work. By means of relevant tensile tests, carried out on carbon steel sheets S235JR with thickness equal to 2mm, it has been pointed out that the rolling process produces in the base material both geometrical and mechanical imperfections. The former consists of the nonuniform modification of sheet thickness, while the latter, much more important from a structural point of view, mainly consists of the variation along the sheet cross direction of the material strength parameters. Further mechanical and geometrical imperfections, due to the subsequent cold forming process, were measured by the EDM method. Finally an analytical model has been proposed to assess the imperfections produced by the rolling process. In such a way it is possible to predict the actual material strength in that point by a simple thickness measurement.