The goal of this Master's thesis was to construct an auxiliary residential object, as a firm and stable steel frame construction. A 3D model of the steel construction was made, as part of the thesis in software SOLIDWORKS 2016 along side analytical and numerical calculation of bearing elements by Eurocode 3 norms. Goal of the task was to analyze a steel construction of an auxiliary residential object, to determine the condition of each construction elements analytically and numerically via use of a computer. Based on those results it was necessary to recommend improved solutions, which can be acquired via optimization in ANSYS Workbench 19.0. The steel construction was split into four categories: ground floor, storey, support columns and roof construction. For the model of construction, European standard profiles were used: IPE 120, IPE 160, IPE 200 and HEA 160 (support columns), and for the roof construction square profile 50x50x6 mm and rectangular profile 120x60x6 mm. Turns out that the analytical results deviate from the numerical results gained from the computer, because it cannot generate a fine grid with enough density (requires more powerfull computers). Results obtained by optimization indicate that it is possible to lower the category of a previous chosen bearing element for the purpose of lowering the mass of the whole construction and by doing so saving on material. Via conducted calculation and optimization conclusion can be made that it is possible to improve the whole construction with a goal of lowering the mass, which means that lighter bearing elements can be used for the same applied load without deviating from safety margins of construction.