The necessity and even inevitability of the building repairing has been shown. The repair as a sustainability development has been emphasised. In building activity – in “on site” practice – a lot of rules of thumb are used. Those rules often seems to be far away from a scientific statement, however, they are a consequence of scientific consideration. In this context, the standard PN-EN 1504 could be treated as the set of rules for repair of concrete constructions. However, the standard is in many cases not easy, complicated and seems to be unfriendly to the readers. On this premise, a commentary to the standard has been developed: “Naprawa i ochrona konstrukcji z betonu. Komentarz do PN-EN 1504”, PWN, 2017, by L. Czarnecki, P. Łukowski, A. Garbacz. This paper attempts to formulate rules of thumb for repairs of concrete building constructions. The rules have been briefly presented on the backdrop of science-engineering relation and illustrated with relevant pictures.