California comes to Berlin

It all started when Lars Triesch, a young design publisher in Berlin, fell in love with the architecture of the American star architect Ray Kappe. From then on, everything revolved around building a house in Berlin in the Mid-Century Modern style based on the designs of the Californian model. But there were a few challenges to overcome. How do you find the right site in Berlin? How can an architectural style designed for the Californian climate be realized in Germany’s harsh climate? What technical solutions are required? And the crunch question: How do you even get an American style icon to design a house in Berlin?


Sometimes the answer is utterly obvious: Call his number! Triesch did some research and contacted Kappe’s office in California, where his sons Ron and Finn Kappe also work. After many conversations and emails, Ray Kappe agreed. Green light for the ambitious project! For Triesch, this was “one of the most exciting moments of my life”, as he writes in his blog on the “Original in Berlin” website.

As expected, the search for a suitable piece of land proved to be a lengthy one, but Triesch finally found the ideal plot in Kleinmachnow in the south-west of Berlin. A wooded suburban idyll where other architects’ houses from the first half of the 20th century can also be found. The ideal location for a Kappe design noted for its spacious, transparent interior design, ample glass and a large proportion of wood. And this is precisely where the special challenge lies, because the house has to meet the requirements of Central European energy standards. A German architect was brought in to execute the designs on site. Alexander Kahnt, who also teaches and researches at Leipzig’s University of Applied Sciences (HWTH), had the decisive idea for this: SLENTEX®. His experience to date in projects with the new BASF insulation had been excellent

Transparent design with new SLENTEX®

So construction work could begin, because the novel high-performance SLENTEX® insulation made it possible to reduce the standard wall thickness by around 50%. Implementation of the original design thus became feasible while at the same time meeting the requirements of modern, energy-efficient insulation. But what is it about the new material that makes it insulate so much more efficiently than conventional materials? No one can answer this question better than Dr. Wibke Lölsberg, in charge of Project Management and Marketing High Performance Insulation Materials at BASF.

“Our high-performance SLENTEX® belongs to a whole new generation of super-slim aerogel-based insulation materials. It is an easy-to-process and non-combustible material based entirely on mineral raw materials.” SLENTEX® has so far been used as a single-layer, flexible and extra-slim insulation mat in the construction and renovation sector. With a value of 19 mW/m•K, the material achieves significantly lower thermal conductivity than conventional mineral-based insulation materials and permits the construction of very thin wall structures. What’s more, says Lölsberg, “the flexible insulation material adapts very well to different building structures while satisfying the toughest energy requirements.”

Construction of the Triesch Residence

The significant slimming of the outer wall enables the realization of aesthetic designs such as Ray Kappe’s architecture, and it results in a gain in space that has enormous economic advantages, especially in inner-city construction. “A feature only offered by this high-performance insulation material,” Kahnt confirms. In the Triesch villa, SLENTEX® was used in two ways. First in the wooden coffers of the timber frame construction and then in the in-situ concrete core with its curtain-type, rear-ventilated façade. “With SLENTEX® it was possible to use prefabricated wooden coffers that were only 20 cm thick. On the concrete elements, the entire curtain wall was only 14 mm thick,” says Kahnt. A real pioneering achievement.

SLENTEX® High-performance insulation. Resource-efficient, slim and durable.

Blazing a trail for climate-friendly and sustainable construction, the product opens up new possible applications and offers architects totally new design freedom – making it possible to implement a Ray Kappe design in the Central European climate zone.

For Lars Triesch and his family, a dream is truly coming true and, if all goes well, the family will be able to enjoy their wonderful Californian architecture with a view of the park scenery in Kleinmachnow by this summer.


Ray Kappe (August 4, 1927 – November 21, 2019) was an American architect and educator. In 1972, he resigned his position as Founding Chair of the Department of Architecture at California State Polytechnic University, Pomona and along with a group of faculty and students, and started what eventually came to be known as the Southern California Institute of Architecture (SCI-Arc). In 2003, Kappe began working with LivingHomes to design modular homes.

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