Berlin House envelopped in cork by Rundzwei.

The fusion between architecture and engineering in a same office are rare gem today in France, as opposed to northern Europe, even if there are French agencies as AIA Life Designers. German agency Rundzwei offers an example with this family house wrapped in cork. 

Rundzwei is a Berlin agency founded by Andreas Reeg and Marc Dufour-Feronce, both architects and engineers. Before they founded their agency, Andreas Reeg was Project-in-chief at Herzog et De Meuron and Marc Dufour-Feronce was Project-in-Chef at London agency ACME. 

Context and location 

Rundzwei had the pleasure to receive a client who wanted a non-conventional house. This request permitted to explore different possibilities; however, the main problem encountered with the urban law. It’s not allowed to build a house with more than one level. One level signifies a 100m2 house for the client but that was too small for her needs.  

As a result, the House designed by Rundzwei is 248m2 in the heart of a Berlin suburban house estate. This plot is divided in two parts with the second house in the back of the plot, which is the case of this house. Therefore, this house is completely hidden from the street. 

Architectural composition of the house 

With many constraints, the urban law is the source of this singular project. Interviewed by Kiiwan, the architect Andreas Reeg explained: “due to strict urban law, we had to propose some ways around planning definition to obtain the area wish by the client. The result is a stepped flooring”. In fact, as you can see on the deployed section below, there isn’t a real ground floor, nor floors, but a sequence of levels which unfold until the office in the attic. 

Thus, the different rooms of the house are surrounded by a staircase that is below a canopy. The central well allows the zenithal lighting to diffuse through the living room across the ground. 

The parents’ bedroom is underground and a panel of glass creates a source of lighting. This choice is the result of the client’s desire to swim without being seen. The swimming pool is 7,5m long and 2,26m large, it is in continuity with the bedroom. This sequence of layout is followed by a bathroom and the dressing room. In addition, a sauna is located under the living room. 

The buried base is delimited by a rammed concrete wall which can be seen equally in the swimming pool. This wall supports the large bays which form a lounge area, it offers a direct connection with the outdoors and plays with the levels, which increasing privacy in the dinner room and lounge. 

The stair creates an echo with the house structure made in wood. No horizontal railing can be seen in the stairs. The architects prefer to use little withe post which permits to accentuate the vertical line of the house.  

A Cork facade 

Cork is an excellent acoustic insulation; it is the reason which can be seen cork in the floors. However, this material has other benefits which permit it to be used in facade. Cork is resistant against mold. Cork doesn’t have any singular treatment, so it is a good choice for environment. 

The cork panels were cut and tailored by a carpentry business which was in charge of all timber structure and cladding. The architect Andreas Reeg relates:” We have equally explored and rendered facades in wood, glass and aluminum. Thanks to a Portuguese employee, we also discovered cork as a cladding material. The use of cork as a covering material is frequently used in Portugal. When we were presented with the different options; our client was immediately convinced by cork. The result we wanted was to make something extraordinary”. 

Cork is made with waste of wine bottle stopper production. These types of materials were compressed and submitted at high temperature to permit to liberate the cork resin. The architect itemizes:” Some buildings with this type of materials were cladded with cork 20 years ago without servicing until today. There are also one hundred years old buildings which were wrapped with cork, although they are dressed in a totally different way. The lifecycle is very long because cork doesn’t break down and is naturally weather and UV resistant. But on the other side, there aren’t many buildings covered with cork which offer a building significant life expectancy. As architects, we believe along with the manufacturer Amorim, that 80 to 100 years is easily possible”. 

Technical and Environmental Choice of Rundswei 

As a point of environmental choice, the architects insulated the house with cellulose wadding and wood fibers. The choice of indoor flooring promotes materials with a high performance against humidity which allows to avoid a complicated ventilation. Rainwater is collected at each corner of the roof and then led to a tank which allows the garden to be watered. The rainwater drains from within the frame so as not to be seen. 

The heating network used is a new German system recently awarded, it uses the heat produced by the fireplace, the active thermal mass, a gas boiler and solar panels by SolarWorld which complement the energy contributions of the house. This House is practically autonomous. 

• Architect: Rundzwei 
• Client: Private
• Manufacturers: Amorim (panneau de façade), Würth, SolarWorld (panneau solaire), Gutex (isolant Thermofibre), Warema, Somfy, Schüco, Fermacell 
• 2016: Studies Started 
• 2018: Completion date