Interview with architect Walter Schelle: “Dekton, aesthetic and functional”
How façade expert Friedrich Scharl reduced weight and costs with Dekton on KAP WEST in Munich
The façade of the new office complex at the Hirschgarten in Munich has a modern, urban look. The original plans using concrete or artificial stone, however, would have made it difficult to meet the tight schedule and to keep within budget. Façade expert, Friedrich Scharl, found an alternative which impressed the architects and developers: the ultra-compact surface Dekton by Cosentino.
Mr. Scharl, you did the technical designs for the façade on KAP West. What was wrong with the original plans?
FS: The weight and the costs. The building was designed with a ventilated curtain façade. The parts of the façade with triple glazing and stone-covered pilasters would have been completely preassembled before delivery to the site and put into place – it’s a typical process that requires a lot of planning and efficiency. The original plans envisaged the pilasters to be covered by 30 mm-thick, fibre-reinforced concrete or artificial stone. This would have meant that each part of the façade would have weighed approximately 1.5 tonnes. With so much weight, handling becomes difficult and the risk of damage increases. In addition, you need an elaborate substructure. In our case, this would have put the time frame and budget at risk.
So you started looking for a lighter façade covering?
FS: Correct, we needed a material with a high-quality stone look, but one that was thinner, and therefore lighter – and all things considered, at a lower cost. And finding a reliable supplier is not as easy as it sounds. Then we discovered Dekton. This ultra-compact surface is extremely stable and at 12 mm thick, weighing 32 kg/sqm, comparatively light. Even thinner material would have been available too. However, we needed this thickness to insert an undercut anchor on the back. With this it is possible to secure the plates firmly and invisibly on the façade.
What was most convincing material wise?
FS: As well as our chosen design options we also needed approval for the façade. Dekton is certified in accordance with ETA 14/0413 and CE 1220‐CPR‐1459. During tests it was proven that the material can even withstand a scale 7 earthquake. The fire protection class is A2. What was perfect for our project was: If a plate cracks, an integrated glass fibre net ensures that the broken piece is held in place. Thanks to its ultra-compact structure, the material takes in very little water. This means extra protection against weathering such as cold, heat and thermoshock as well as increased shape stability which allows for very close tolerance gaps of just +/-0.5 mm each. As well as the quality of the material, the quality of the supplier was also important to us. Would they be able to delivery 13,000 sqm “in time and quality”?
What impressed you about Cosentino as a supplier?
FS: We went there, together with the developers, the architects and those building the façades, as well as the people from Cosentino in Germany. The production facilities in Spain particularly impressed me. Dekon is produced there at a size of 3,200 mm x 1,440 mm in a continuous process, which means that the plates of one batch have the same quality, texture and colouring. Then follows the individual cutting and post-production work, which in our case means working the edges, mitre cuts, setting the undercut anchors and the clasps. The pre-assembled parts were then stored and delivered to those building the façade piece by piece – this was extremely reliable and in the correct order, which when working with 400 different elements and approximately 15,000 covering parts is a true piece of logistical mastery.
What effect did using Dekton have on the façade?
FS: Dekton looks aesthetically pleasing and is very good functionally. With the low weight of the façade covering, even the subconstruction could be made more simply and lighter compared to the original plans. It is now self-supporting. Using the façade building app in Germany, the aluminium profiles from Wicona were planned with the glazing and insulation, the sun screens and the electrics. Finally, the prefabricated Dekton plates were hung and secured. Each part of the façade is now about one-third lighter than at the beginning of planning. Instead of 1,500 kg, the weight is just 1,000 kg, which made transport and assembly much easier.
Were you able to keep to schedule and within budget?
FS: We had two teams on site, each with three employees. They worked parallel on different parts of the building and crane-operated, placed and assembled the elements in 20-minute intervals – 2,000 elements for about 12,600 sqm of façade in just seven months. It was just like clockwork. In addition, by using Dekton instead of concrete or artificial stone, we were able to reduce the cost by about 20 percent per square metre. The developer is happy since by doing this we kept to budget and schedule.
Mr Scharl, in which situations would you advise planners to take Dekton by Cosentino into consideration in particular?
FS: Dekton should always be considered since it offers a large range of design possibilities and is lighter than stone or concrete. The ultra-compact material is also more resistant and sustainable than glass or sheet metal. What really impressed me was the ability of the company to produce around 13,000 sqm of material with the same quality, colour and texture in less than a week. Not only the production, but also the technical and logistical coordination, as well as the communication with those building the façade and us as the technicians and the architects, was very good and reliable. This is extremely important on a big project like KAP WEST, where planning security in a short time frame makes all the difference and helped all involved do a super job.