The application of the finite element method (FEM) for the calculation of brick structures of a single-storey building at the design stage is considered. The stress-strain state of the critical masonry of the building is restored. For this purpose, the deformation theory of plasticity of A.A. Ilyushin, the dependence of stresses on deformations according to existing norms for the calculation of brickwork of buildings is applied. The results of full-scale testing using the method of non-destructive testing are analyzed. As a result of monitoring the technical condition of non-existing structures of the building under study, defects that appeared at the stage of construction of the building and during its operation were revealed. The results obtained by the two methods were compared, the degree of wear of masonry building structures was determined, after which recommendations were developed to improve the current technical condition of the brick building under consideration. It is established that after the completion of repair work and during the further operation of the construction object, it is necessary to comply with the requirements for the current constructive prevention of the building on the basis of the requirements of the current normative acts. The possibility of the superstructure of the second floor superstructure on existing structures was also analyzed. It is revealed that at the moment it is impossible to perform the superstructure, since in order to make it possible to perform the superstructure of the second floor, the conditions must be met to strengthen the structures for the safety of the operation of the lower floor with an increase in the load on it due to the support of an additional floor on it.