BAU 2015 Team Building No. 3: Sustainable building with wood and rammed earth
Special materials demand special expertise – and good teamwork! In the third of our BAU Team Building Interviews, we look behind the scenes of a very special project.
The Swiss architects at Barcelo Baumann and the processors from Lehm Ton Erde Baukunst of Austria have together created a new educational building at Merian Gardens on the southern edge of Basel. Built in wood and earth, this new structure fits perfectly into the sustainable environment of greenhouses, historical buildings and other commercially used facilities. We asked both architects and processor for their perspectives on this exciting project.
Participants of the BAU Team Building No. 3:
Lehm Ton Erde Baukunst GmbH,
Barcelo Baumann Architekten GmbH,
This cooperation between the two of you has produced an excellent result that perfectly blended the skills of both sides. How would you describe this cooperation in general?
The cooperation was very good. The architects Barcelo and Baumann contacted us very early on, in the competition phase. As a result we were able to give them a very early cost estimate for the earth facade and work out with them all the earth-specific details and interfaces to the various building trades.
Building this structure in wood and earth meant that we needed special solutions not conventional ones, so good understanding between the two sides was very important to us. All through the process we discussed the details and developed the ideas together, exchanging sketches and plans until we had a workable solution.
Haben Sie zuvor bereits bei einem Projekt zusammengearbeitet bzw. wie kam Ihre Zusammenarbeit zustande?
Our first contact with the architects was through them approaching us with this inquiry. In the competition phase they had already thought of using rammed earth for the facade, which we thought suited the building well and it was also welcomed by the client.
Back in the competition phase we had already suggested earth as the building material for this project. And during that phase we had our first contact with Martin Rauch from Lehm Ton Erde Baukunst, to clarify some initial questions with him. Once we had won the competition and were starting work on the project, more conversations followed and discussions on possible solutions for the details. With the client we then inspected and explained the production and processing of the earth in the factory. The next phase was to build a full-scale model of the facade, which was then used to discuss specific details.
Mr. Barcelo, can you describe how you convey your ideas on the design to the processing firm or the building workers?
We try to set out our ideas as clearly and unequivocally as possible on plans and in the descriptions, also in talks. We work very closely with the building trades – we listen to the suggestions of the specialists in each trade and incorporate that input into our work on the execution plans.
What are the criteria you look for when you are engaging tradesmen or processors to work with you on projects?
This is a little different for each new task. Where possible we work with tradesmen we already know and with whom we have had good experience. Sometimes, however, we have to put out larger tenders, or the client wants us to take into account particular building firms – that can of course lead to new contacts and experiences.
Martin Rauch, at what point in the planning are you normally brought on board?
That varies widely. Sometimes we are approached in the competition phase, as in this case, but mostly afterwards, i.e. in the design stage. There are a number of special aspects when building with rammed earth that can also influence the design. The earlier we are involved in the planning, the better. If we aren´t contacted until after the design stage, it´s often a difficult job to shape the design so that it can be built with this material. Because not everything that you can do in concrete is also possible in rammed earth. As rammed earth is not reinforced, it can´t cope with the same level of tensile forces.
What kind of ideas or visions do architects and planners approach you with? And how often do you find that those ideas have to be treated as a special case?
Since there are no standards regarding rammed earth, virtually every idea and every inquiry is a special case. But that is precisely where our strengths lie and it is an incentive for us. We like to develop new solutions. And we have built up a lot of experience in this area. In recent years, for example, we have made significant progress in the prefabrication of rammed earth components.
What qualities do you most like to see in an architect?
A passion for the material of rammed earth and a willingness to consider alternative ways of doing things. .
Let us return to your joint project for the rammed earth building at Marien Gardens in Basel: How does the building react to the different conditions?
The building blends very naturally into the historic setting. The basic orientation of Brüglingerhof with its open spaces is continued in the placement of the new building. The choice of building material derives from the function of the building. The chosen building materials ensure a balanced indoor environment with ideal humidity, they are easy to maintain and fully recyclable. Vapor diffusion occurs across the entire wall construction so the building can “breathe”.
What was the brief and what solution did you come up with?
As the building was a combination of timber and earth, fast construction time on site was important, so that we could get the large, overhanging roof on as quickly as possible. That´s why we opted to prefabricate the components. We were able to produce the rammed earth components in our factory, independent of weather influences. Assembly on site was therefore very quick and we were able to keep to the very tight time schedule.
A design for a building with education and training facilities was needed for the agricultural and environmental education projects at Merian Gardens. The requirement was that it should be multi-functional and of an eco-friendly construction. The new one-storey earth building we proposed echoes the surrounding listed barns in that it has a solid ground course as a main theme on the facade. Four different spatial volumes, containing the infrastructure, enclose a large hall in the center. Independently usable entrances are located on the two narrower sides of the building; on the long sides the large glazing units can be opened, functioning like wide doors to the private courtyard and the planting areas beyond. The roof, with generous overhang and only a gentle pitch, spans across the four volumes to create a unified overall structure. The roof soffit, clad with a three-dimensional grid of wood with a glazed finish, continues in the central space, thus connecting internal and external space. A characteristic feature of this new building is the combination of traditional materials and new techniques to produce a contemporary, sustainable and eco-friendly building.
What changes were implemented between the initial design and completion?
Only very few, and they were at the request of the client. For example, changes to details such as the size and alignment of the bread ovens in the kitchen and the divisions in the office for the teaching staff.
What special considerations applied to the use of the material on site?
The processes in placing the earth components were very important: First the prefabricated timber components were erected for the four room volumes, then the earth components, also prefabricated, were placed in front of these and fixed to the timber frames. Only then could the roof girders be positioned, as otherwise they would have hindered the positioning of the earth components.
Project: New building, "Lehmhaus Merian Gärten", Basel, CH
Architect, interior designer, lighting planner: Barcelo Baumann Architekten BSA, Basel, CH
Project team: Jordi Barcelo, Katrin Baumann, Gregor Katz
Processor and manufacturer: Lehm Ton Erde Baukunst GmbH, Schlins, AT
Client: Christoph Merian Stiftung, Basel, CH
Timber construction: Hürzeler Holzbau, Magden, CH
Building engineering systems: Classen Haustechnik, Basel, CH
Structural engineers: Nicolas Zeuggin - Ingenieure GmbH, Basel, CH
Sanitation planning: AquaPlaning, Arlesheim, CH
Landscape architect (in the competition): Vogt Landschaftsarchitekten AG, Zürich, CH
Photography: Christoph Merian Stiftung / Kathrin Schulthess, Tom Baumann