“Protective veil” for High Cathedral Church Cologne
The Cologne Cathedral Cultural Foundation has now had a three-metre high and approximately 47-metre long wrought iron grille installed to protect the imposing structure in the area of the portals of the transept with the starry carpet in front of it and the entrance area of the cathedral treasury from vandalism and soiling. The contract for the planning and execution was awarded to the artist and architect Johannes Nagel. Sculptor Paul Nagel, Johannes Nagel's father, had already been working on the design of the grille in early 2016. After his death in the same year, his son Johannes Nagel was able to continue the planning and realization, in collaboration with master blacksmith Wolfgang Ripke, in an art forge (Metallwerkstätten Nagel Herdt) founded especially for this project and completed it in the summer of this year.
The fence, which looks like a “protective veil” with its numerous floral ornaments and some pictorial representations, is similar to the existing fence on the main south-facing side of the cathedral. Standing on a small plinth, which also serves as a base for four tall columns, it fits in perfectly with the north façade. The columns, made of basalt, with fine pilaster strips and a stonemason's relief of the surfaces, stand exactly in the axis of the buttresses of the façade.
Safe, aesthetic and unobtrusively functional
Even before the two-metre-wide, 400-kilogram grid elements were installed, a linear drainage system was installed directly in front of the plinth to protect the medieval vaults of the cathedral treasury under the portal area. The basis of the drainage system is the ino 610 KR stainless steel box channel with edged grate supports arranged at different heights for different cover variants.
The channel covers were designed as lockable elements that can be filled, specifically to meet the requirements of Cologne Cathedral to install drainage elements on the enclosure of the north portal that are as inconspicuous as possible. The cover elements were lined with the same basalt lava slabs as those installed in the surrounding area.
Widened joists on the filled covers create lateral inlet slots parallel to the gutter edge to collect the rainwater. In areas where the base directly adjoins the gutter, a stainless steel longitudinal bar grating is attached to the side of the fillable covers. The enlarged inlet cross-section created by the longitudinal grating ensures immediate and rapid water drainage and therefore also protects the basalt base from splashing.
The individual channel elements, which are up to 4 m long, have wide welded-on locking or adhesive flanges on the outside to connect the waterproofing underneath the surface covering. By welding the individual elements together to form a watertight gutter line, as well as additional measures to seal the structure, it is ensured that no moisture can penetrate into the vaults of the cathedral treasury below. The channel system selected for Cologne Cathedral is suitable for light traffic and barrier-free access in accordance with DIN EN 1433. The cover (longitudinal bar grating) meets the slip resistance requirements of BGR 181 in accordance with DIN 51130 and the slip resistance class of covers in accordance with DIN EN 1341 for outdoor areas.
