The vibrant Berlin district of Kreuzberg is home to the subway station Südstern, opened in 1924. After more than 80 years of subway operation it was time for an extensive renewal, which took place between 2010 and 2011; the objective was a fundamental repair and providing handicap accessibility. Focus of renovation of the area behind the track: the severely damaged walls. Here the aim was to remove the existing tiles and a large part of the concrete substructure to create a stable substrate layer for the new covering. The idea of the concept was, after a rough concrete repair of broken out areas, to attach the required surface compensation by anchoring a reinforcement to the substrate. For the respective pretreatment of the substrate, the injection resins PCI Apogel PU and PCI Apogel E were used; this allowed optimal grouting of cracks with limited elasticity. Next, reinforcement meshes made of stainless steel were applied, and the prepared concrete surfaces sprayed in wet spray process with the light repair mortar PCI Nanocret 70. To ensure absolute evenness, the areas were then reworked with the cladding reinforcing concrete compound PCI Nanocret 10 in wet spray process – the perfect basis for a new ceramic covering.