The course focuses on the causes of technical risks associated with the continued operation of structures. Students will be familiarised with factors that can affect the quality and reliability of structures - repairs, maintenance, the decision to demolish. Introduction to the testing of structures (in a test room, in situ). The classes will be supplemented by practical demonstrations of testing, the design of a sampling plan and the assurance of its representativeness using simple tools for the qualification quantification of risks and danger - based on the assumption of minimizing systematic survey errors. Attention is paid to the most common mistakes contractors make, and their prevention. Overview of the ecological and aesthetic function of reconstruction and repair, and in particular the protection of completed works against negative environmental influences.