The task of this final work was to design the reinforced concrete structure of the car showroom, which has a gross floor area of 832.5 m2. The design was carried out in accordance with engineering practise and the Eurocode standards. In the work, the arrangement of the structural elements was determined and then a manual calculation was carried out. In the manual calculation, the thickness of the protective layer, the calculated strength of the materials used in the construction, the static heights of the cross-sections were determined and the loads on the structural elements were analysed, which were used to calculate the bending moments and forces on them. With the calculated values, a further calculation was carried out, which finally determined the amounts of reinforcement to be incorporated into the structure to make it safe and reliable. The computer programme used for the design calculation is SAP2000. Finally, the results obtained by manual calculation were compared with the results obtained by calculation with the SAP2000 programme. In principle, the programme calculates a larger amount of reinforcement to be placed in the slabs, but this is not the case for the positions of the slabs above the support. The programme has assumed the same amount of longitudinal reinforcement for all beams, but a different amount for the transverse reinforcement. In the manual calculation, the longitudinal reinforcement is greater for the positions of the beams in the centre of the span, with the exception of position 207, and the transverse reinforcement is greater for all positions than in the calculation with the SAP2000 computer programme. Although the software requires a larger amount of reinforcement to be installed in the slabs than the manual calculation, this is not the case for the areas above the supports, where the manual calculation is rigorous. In summary, unlike the conservative manual calculation, the software in some cases simplifies the design process, thereby increasing cost efficiency.