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Reprint from the customer magazine “ContiTech initiativ 02/03”



windows! And every one is different! Uta Fröhlich’s apartment has character – and hardly any straight walls. “I feel at home here”, says the woman who was one of the first tenants to move in to the “forest spiral” designed by Friedensreich Hundertwasser in Darmstadt. In the meantime she has got used to the rounded surfaces in the 100 m2 area of her apartment, just as she hardly notices the scores of people who have been coming to look at the crossstriped house in the municipal park district since September 2002. Not all the apartments in the “forest spiral” are as crazy as Uta Fröhlich’s. “Our habitat only looks unusual from outside”, says Ruth Seitz, “everything is perfectly normal inside.” Hundertwasser devised the plans for this huge building that some people compare with a multi-layered angel cake, others with a theatre and box seats or an ornate fairy-tale castle. Art or kitsch? In any case it is a colourful gem, an architectural objet d’art. Living in harmony with nature is a tenet of the philosophy of Hundertwasser: “Modern architecture enslaves its occupants with technocratic heresy: People have become dependent on gas, electricity, telecommunications and have lost the ability to survive in nature. That’s why I build organic, living architecture, to hold back this mania.” So ecologically inspired building was the remit of the commissioner of the “forest spiral”. The Darmstadt building association spent approx. 24 million euros on the complex structure with its bold flowing contours that was completed by Holzmann AG in two years. Hundertwasser prepared the blueprint and oversaw the artistic direction, while the architect Heinz M. Springmann bore responsibility for the planning. The façade incorporates elegant lines, trees grow on the turf-covered roofs. Onion-shaped towers, colourful columns, a golden cupola, small streams and decorative balconies dominate the scene – you can see that Hundertwasser had a hand in this. The Viennese artist designed the 105 apartments with no less than 1048 windows. The smallest unit has floor space of 47 m2, whereas the largest immediately under the roof is more than three times this size. The square metre price is currently approx. 10 euros. The complex building favours spirals, as opposed to straight lines. Animated, uneven surfaces and curved paths lead to a walking experience impossible on flat unnatural urban roads. The gently cupped stairs appear to have been worn down by decades of use. Another feature is the rounded outer walls that have very different radiuses and in some cases even irregular contours, as if drawn by hand. Some outer walls of the tower are up to three degrees out of true, that gives the building a rejuvenated appearance as you pan up to the top. It’s hardly surprising that the unusual shape and construction of the building makes special demands on the load-supporting components

Hundertwasser left his unmistakable mark on the “forest spiral” in Darmstadt. But Calenberg knowhow also plays a part in the project: Special mounts play a supporting role to this multi-coloured building in the literal sense.

Apartments with character: Curved lines, plants growing on the roof, and golden onionshaped towers are features of a distinctive style of architecture.

Photos: R.Vonderschmitt (5)

and their bearing performance. This is where the know-how of specialists was needed. Specialists such as the former ContiTech employees who founded the company Calenberg Ingenieure (Salzhemmendorf) and their partner Heim (Langen). From the extensive range of Calenberg elastomer mount systems, suitable solutions were found for the various points of support. This was firstly the flexible mounting of the ceiling of the underground parking area. “Underneath the building there is a basement garage whose ceiling was flexibly mounted on Calenberg S 65 compact mounts and on the Cigular ceiling mount that can withstand shear forces”, explains Reinhard Rühl of Calenberg Ingenieure that has its mounts manufactured at ContiTech. “The dimensioning, designing and selection of the elastomer mounts had to consider parameters such as internal force variables from static calculations, shrinkage and the creeping of ceiling plates as well as fire-protection and design specifications.” For all mounting elements, the requirements of fire rating F-90, according to DIN 4102 , had to be complied with. Steel-reinforced but resilient Calenberg Ciparall friction bearings were used wherever static calculations indicated large vertical loads subjected to shear forces in a horizontal plane. “In this way we not only completely met the requirements of support structure planning, but, by splitting the load-bearing mounts into separate sections, were also able to provide the builder with an extremely economic solution”, Rühl points out. In addition, Calenberg Ingenieure developed a subsonic noise-damping flexible mount for the flights of stairs. Any large house has a lot of life in it, and this applies especially to the “forest spiral”. Noise and vibrations are an integral part of this. Who hasn’t been annoyed by neighbours making a lot of noise as they go down stairs. Technically-minded people like Rühl put it this way: “Anyone walking on stairs generates noise

Friedrich Stowasser was born on 15th December 1928 as the son of a Jewish family in Vienna. Even while he was a pupil at the Montessori school, his exceptional feeling for shapes and colours was apparent. From the 1960’s he called himself Friedensreich Hundertwasser. At the Academy of Arts he only lasted three months. He obtained guiding inspiration in meetings with other artists and by attending exhibitions. Egon Schiele and the French painter René Brô served as models for him. Hundertwasser wanted to make the world more attractive, in harmony with nature and human creativity. He replaced sober rationality with a romantic flirtation with nature – examples of this are the Hundertwasser house in Vienna, the Martin-Luther Grammar school in Wittenberg (Saxony) and the Hundertwasser train station in Uelzen (Lower Saxony). Hundertwasser died aged 71 in New Zealand, his last country of residence.

and causes structure-borne sound in the form of subsonic noise, that, if unchecked, spreads throughout the building and the resulting radiation of secondary airborne noise leads to an impairment of living comfort under these conditions.” In the “forest spiral” noise is not a problem: By using “bi-Trapez” elastomer soundproofing mounts, the flights of stairs are decoupled from the rest of the building. “This enables an improvement in the subsonic noise of up to 23 decibels”, says Rühl proudly. That is even more than the legal requirement. DIN 4109 supplement 2
Support for the Hundertwasser house: Elastomer mounts enabled the technically challenging building project to be realised at reasonable cost.

CON tact
Reinhard Rühl Calenberg Ingenieure Phone: +49 5153 9400-0 E-Mail:

requires an improvement of 17 decibels to give greater protection from subsonic noise. The “forest spiral” in Darmstadt really is something else – from mounts in the stairs preventing structure-borne noise to the tree growing on the roof. Hundertwasser sketched the first draft of this project on a paper napkin in a Viennese restaurant. He was no longer around to attend the opening ceremony of this masterpiece. So he was unable to enjoy the raptures of his friend and curator of his estate Joram Harel about the “dancing windows” and the comments of the Lord Mayor Peter Benz: “The house is a symbol for the cosmopolitan attitudes and the liberal-mindedness of the city.” Maybe Hundertwasser would have been even more pleased to hear the commendation of the tenant Uta Fröhlich. “There’s no way I’ll part with any of my 17 windows.” s


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