When renovating historic buildings with facades worth preserving, the use of internal insulation is often the only way of thermal renovation of existing exterior walls. On the basis of the analysis of the building stock, suitable insulation concepts have to be developed. Demanding renovation planning, taking into account the requirements of the preservation of historical monuments, includes the determination of potential moisture-related causes of damage and the elaboration of measures for elimination and future damage prevention. In this paper, a renovation guide is presented that translates the scientific results of building physics research into renovation practice. As part of the knowledge transfer, the authors have been involved in renovation projects for years, using the methods and software tools they developed themselves. The individual steps of the refurbishment guide are explained using examples from refurbishment practice, starting with an on-site inspection, carrying out in-situ tests and measurements and determining the material properties in the laboratory. On this basis, necessary immediate measures for building protection can be formulated, and together with the owner / architect, various options regarding the intended use of the building and the actual condition determined in the investigation phase are developed. The development of the planning guide also allows conclusions to be drawn about the applicability of the simulation tools developed in the scientific environment and promotes their further development towards fully-fledged, economically usable planning tools.