Architect Walter Schelle on his experiences with Dekton as a façade covering on KAP WEST in Munich. With its two distinctive towers – 60 m and 53 m high to the South and North respectively – KAP WEST, from which you can see as far as the Alps, dominates the western entrance to the city centre. The façade of the cubic complex is characterised by a diverse netting structure of floor to ceiling windows and stone-covered pilasters. The uniform and extremely precise processing of the surfaces was made possible by the use of an innovative, ultra-compact material.
Mr. Schelle, you led the planning of KAP WEST at HPP Architekten. What were your aims?
WS: On one hand we wanted to implement the design and construction ideas of the plans from Wiel Arets Architects as well as we possibly could. On the other hand, the developers OFB Projektentwicklung GmbH had a clearly set out budget and time frame for the execution. Throughout all building projects there are many situations in which you develop and implement solutions as the lead architect to bring together both sides. This is best done on site. This is why the HPP office in Munich was contracted to plan the construction of the building and the tender for the façade.
What challenges did you face with the façade?
WS: The plan envisaged rear-vented curtain façades made up of elements with aluminium-framed, floor to ceiling windows and stone-covered pilasters. The elements were to be delivered complete, including triple-glazing, insulation, shadowing, electrics and covering. On site there is very limited assembly space. In addition, the most efficient installation had to be guaranteed. A quick, compartmentalised completion of the façades finally turned out to be the key to the construction of the interior and, therefore, the earliest possible handover to the users.
Why then were the stone pilasters so important?
WS: The vertical and horizontal pilasters help to give the façade structure. At KAP WEST their width is slightly different, just like the windows. This makes it look like it’s alive. At the same time, everything gives the impression of being from a single cast. But, it wasn’t just for design reasons that the pilasters were important. They also facilitate the integration of the rail-guided sun-protection system and are important for airborne sound insulation. The building stands between one of the heavily-used roads and the platforms of Munich Central Station. Without the weight and the structural function of the pilasters it would not have been possible to reach the required sound protection limit of 47 dB.
“We needed a material that was both aesthetically pleasing and functionally first class. Then we found Dekton”
Which materials came into consideration for the covering of the façade?
WS: Originally, glass-fibre reinforced artificial stone or synthetic stone was to be used with a 30 mm thickness. However, these options were unsuitable for the 12,600 sqm façade due to their weight and the costs involved for handling, not to mention the complex subconstruction. Together with the façade expert Friedrich Scharl we looked for an alternative which had a stone-look but one which was lighter and less costly. We needed a material that was both aesthetically pleasing and functionally first class. Then we found Dekton. We were able to use this material in thicknesses of just 12 mm. Instead of weighing around 1,500 kg, the façade elements with Dekton weighed a third less, around 1,000 kg.
Does the reduced thickness of the material have any disadvantages?
WS: Our worries about the stability were quickly allayed. Cosentino calls Dekton an “ultra-compact surface”. What that means was first made known to us during our visit to the plant in Spain. Without adding organic binding materials such as resin, up to 20 natural materials are compacted under 25,000 tonnes of pressure and heated in a sinter process so that the level of resistance of the high-density plates becomes extremely high. The material is weather resistant, resistant to shocks, scratches and staining and holds its shape and colour. Even graffiti can be washed away, which is important in areas close to the ground.
Did you have to make a design compromise due to this?
WS: No, not at all. Dekton is available in over 60 varieties, even made-to-measure designs and textures are possible. We chose the colour “Keon” from the “Cosentino TECH Collection”. It is inspired by concrete, but makes KAP WEST stand out from other buildings in the area. The extreme flatness and precision of the plates is also important. The tolerances are just +/- 0.5 mm. This meant we could make the façade with very exact and tight joints of just 10 mm. The idea of the original, cubic design with a modern, net-style sleeve, was perfectly replaced by Dekton.