The paper consists of a theoretical and a practical part. The theoretical part describes the determination of the optimal thickness of the concrete protective cover in order to ensure the required durability of RC structures. In the practical part, an assessment of of the RC structure of the sports center "Sajmište" was carried out. In order to determine the degree of damage and propose repair measures, a detailed visual inspection of all available structural elements was conducted. Based on the analysis of registered defects and damages, results of in situ tests, control calculation that corresponds to the new function of the building and the architectural solution, a proposal for repair measures was provided in order to ensure the load-bearing capacity and durability of the newly designed RC structure.