More than 80% of all floor tile coverings are laid in renovated or modernised buildings as opposed to new buildings and this figure is expected to increase in the future. Furthermore, renovation and modernisation take place in commercial and industrial premises as well as private residences. In particular, the redesign of floors with ceramic tiles, slabs or natural stone is becoming increasingly popular. However, very often the substrate cannot be regarded as a stable surface suitable for supporting a tiled or stone covering and the building materials industry and craftsmen are faced with a significant challenge. Based on two German case studies (a farmhouse and a winery), the challenges faced in the modernisation of old buildings are examined and the applied solutions described.