Expressive natural stone cladding with custom-fit protection
Churches are not often built these days, but that is not the only unusual thing about the expressionist-looking new building in Munich’s suburbs. In addition to ceramic tiles, local Nagelfluh was also used. The solid natural stone had to be prepared for different interior and exterior requirements.
Rupert Mayer was a Jesuit priest who was part of the Catholic resistance in Munich against National Socialism and was beatified in 1987. The apostle of Munich, as he is also known, is the patron saint of the gleaming white and light-flooded new church building, which was erected between 2015 and 2018 in the municipality of Poing, an eastern suburb of the Bavarian capital. The special shape of the Seliger-Pater-Rupert-Mayer-Kirche not only impressed the Association of German Architects, which awarded the building one of Germany’s most important architecture prizes, the Great Nike, but also the local population. While the Baumeisters had a crystalline form in mind when designing the solitaire – in the sense of a free-standing building that stands out from the surrounding buildings – the congregation is reminded of winter sports. They affectionately call their new church “God’s ski jump”.
15,000 ceramic tiles cover the 30 by 30 meter high polygonal roof construction and make it shine in the right light. The 3D ceramic tiles were produced and glazed by hand by m&r Manufaktur from Ransbach-Baumbach using slip casting, a mold casting process from traditional porcelain production, according to a design by the architectural firm. As a contrast to the delicate shapes of the tiles, the solid plinth area of the façade as well as the wall plinth and the floor area in the interior of the church are made entirely of polished Brannenburger Nagelfluh from the Upper Bavarian gravel plain by Grad Nagelfluhwerk GmbH & Co KG.
Nagelfluh is a conglomerate rock that contains rounded rock fragments of various origins. Rock fragments from the central Alps were displaced by mountain streams into the Alpine foothills, where they were deposited and filled and solidified by the overlying pressure of younger sediments and lime precipitated from the groundwater. Due to the high proportion of binder, the natural stone has a homogeneous overall appearance despite the different rock inclusions. The time of formation can be dated to the Pleistocene, making Nagelfluh a rather young rock. The open and clearly visible pores are typical of its appearance. The Brannenburg Nagelfluh originates from a Nagelfluh massif in the region of the same name, which formed during the Würm Ice Age. The rock has been quarried there since the 10th century. In southern Germany, Nagelfluh can be seen in many buildings, for example the front of the building and the large portal of the Ludwig Maximilian University in Munich or the foundations of the Frauenkirche in Munich and the Old Technical Town Hall in Munich. Less common is its use in new buildings, such as the Seliger-Pater-Rupert-Mayer-Kirche in Poing.
The nine-centimetre thick facing brickwork made of solid Nagelfluh was to be protected against graffiti in particular, but also against other environmental influences. Due to the typical structure of the natural stone, the absorption capacity of the substrate varies. When removing dirt and paint, residues could remain on the unprotected façade.
The choice fell on the prophylactic surface and graffiti protection PSS 20 from PSS Interservice GmbH. The protection system met the specifications of the client, the Catholic Church Foundation of St. Michael: the barely visible coating is completely reversible and its formulation based on polysaccharides and carbohydrates – i.e. sugar and potato starch – met the requirements for environmental friendliness. “It is a purely plant-based product without any chemical carrier,” assures Bernd Pfennig, the PSS Interservice consultant responsible for protective coating measures on sacred buildings, “which is why it is also popular with monument conservation authorities.” PSS 20 forms a wafer-thin film on the surface of the Nagelfluh and protects against graffiti as well as general soiling such as splash water, de-icing salts and dog urine. “Natural stone has a capillary system; impurities easily penetrate the stone through the open pores and change the appearance of the surface. The porosity of natural stone is therefore the actual cause of soiling, and this is where specific surface protection systems can help,” explains the expert. The natural stone façade nevertheless remains completely open to the diffusion of water vapor; the little moisture that penetrates can be immediately released again via the vapor phase.
Read more in STEIN 8/2019.