Our office was involved in this project for the preparation of the required study of structural assessment and retrofitting of the existing four-storey building, with a roof and basement, made of reinforced concrete, in the framework of the project “Reconfiguration, energy upgrade & change of facades of the building”. The building was planned for the addition of four storeys but due to the above-mentioned structural arbitrariness it was necessary to check the structure for the addition of the new storeys. The load-bearing structure of the existing structure consists of reinforced concrete beam-and-beam frames and the same applies to the newly built floors. For the assessment check, elastic dynamic analysis was carried out, namely the  Time History Method (ΚΑΝ.ΕΠΕ, §5.6.3.3) with local indices m. The solution and assessment check were carried out with the software FespaR 22 v.8.3.0.16 from LH Software.