Opening a new chapter in the disappearing tradition of rammed-earth construction, Martin Rauch has advanced fabrication methods and persevered in extensive experimentation to create stunning structural engineering innovations
Rammed earth had almost died out. The machine age had pushed it to the sidelines and earthen construction suffered under the modern demands for efficiency, logistical ease and regulatory standards. At the end of the 20th century, the building technique seemed to be on the verge of extinction. But the embers still smouldered in the ashes. In Matteo Thun’s master class at the University of Applied Arts in Vienna in 1983, Martin Rauch decided to conduct research on unfired clay as a final project. ‘I was instructed to produce a tea set for the final project. But the unfired material interested me much more, since it offers a lot of scope with respect to expression and applications’, Rauch recalls about his idiosyncratic and courageous decision. The young student immersed himself in the possibilities and properties of the fragile material. With this work, Rauch established the basis for his decades-long examination of rammed earth, and coined the multifaceted triad of Lehm, Ton, Erde, or ‘loam, clay, earth’ – Lehm standing for craft and technology, Ton for artistic design, while the term Erde stands for the sustainability of the material. ‘I still remember ruminating on a title for my final project in a coffee shop and hitting upon the three terms in the process’, Rauch reminisces, ‘It seemed quite well rounded to me. But, at that time, I could never have imagined that it would accompany me for such a long time.’
Haus martin rauch sketch drawing architectural review
Without having any idea how formative this decision would be for his life and how far his examination of the building material would take him, Rauch took up the loose ends of this tradition. After his studies, he returned to his hometown of Schlins in the Austrian state of Vorarlberg. Not only a ceramicist – before attending a technical college for ceramics, Rauch had tried furnace construction – it comes as no surprise that he initially built rammed-earth ovens. The three-dimensional moulded sculptures, bringing together the two archaic elements of earth and fire, facilitated a synthesis of topics that continue to inspire him. Named ‘Lehmos’, they still provide the basis for Rauch’s business today.
In 1986, Rauch entered a competition for motorway noise barriers to be carried out across Austria. Despite being awarded first prize, the competition design was not realised – the project was too far ahead of its time. But it did lay out the conceptual framework for what would follow: the material could be excavated and used as a building material directly on site, and thanks to adapted processes using framework and machines, earth could also be suitable for industrial fabrication. Ironically, these early unbuilt ideas will now be realised in eastern Germany. ‘Back then, the idea was too progressive’, Rauch remembers. ‘In the meantime, many things have apparently changed in the construction industry along with the awareness of ecological issues. What was missing back then now exists.’
Rammed earth perspective technical drawing martin rauch architectural review
In the early 1990s, the scale of the walls that Martin Rauch was able to realise steadily increased. One milestone was the curved wall in the regional hospital in Feldkirch (1992-93): the 180m-long, 6m-high wall improves the indoor climate with its vast surface, and forms the central element of the interior design. With every project, Rauch grew more acquainted with the material. Everything was based on trial and error and built on careful analysis of the material. The few specialist books on the topic came from a time when handcrafted production was still affordable. Rauch had to break new ground, and experimentation was the only solution.
To provide evidence that earthen walls were durable and are able to store heat and humidity, Rauch constructed a new workshop for his company (1990-94) in Schlins with the architect Robert Felber. As builder, Rauch was able to execute the details as he had imagined them, and examine how the material behaved over time first hand. ‘At the beginning, everyone had reservations about building with earth’, Rauch says when looking back at this early period. ‘No one knew how the walls would behave when exposed to weather. I always had great confidence in the material – there are indeed earthen structures that have been standing for hundreds of years. But I had to prove that it is also possible to build with rammed earth sustainably in the here and now.’
Despite all the joy of experimentation, there is wisdom in the tradition of earthen construction: every earthen structure requires dry feet and a good hat. Water welling up from the ground weakens the stability at the base; if rain falls on the wall coping unimpeded and flows downwards unchecked, the wall begins to erode and the water run-off washes the material away. One solution is mixing in cement, but Rauch firmly rejects this. ‘Interfering in the material properties of loam is detrimental. One thus takes away its most important characteristic, since the material can only be integrated into the cycle of materials again without admixtures. When being dismantled, the wall once again becomes the earth from which it came. This is absolutely essential. This challenge has to be mastered by means of the building technique and the construction – not by altering the properties of soil for the worse!’
Rauch house roger boltshauser martin architectural review earth 01
Source: Bruno Klomfar, Vienna
Schlins workshop martin rauch architectural review
Source: bruno klomfar, vienna
Rauch went on a search for preserved historical examples of how previous generations resolved the issue of erosion, including the pisé construction technique common in France, in which rammed earth is used without an added, visible layer of plaster. Further away, he studied the local tradition of earthen construction in Tanzania, where his elder siblings were engaged in humanitarian projects energetically supported by Rauch.
But no matter how much research he did based on the historical models, it was not the earthen construction that he envisioned for a new millennium. The traditional building technique protected the exposed soil with overhanging roofs and heavy bases. Would it not also be possible to erect finer structures oriented towards Classical Modernism? Could the material be given contemporary expression based on its characteristics and processing? This is the vision that still drives Rauch today. ‘I want to build contemporary forms. And I also want to expose the earth, since it is a wonderful material from a creative perspective, and its outstanding structural-physical properties only come into play when it remains unclad.’
Haus der arkitektur graz erosion eva guttman olafur eliasson architectural reivew
Source: markus tretter
After developing structural details in his studio, Rauch was able to realise a first house (1993-96) with visible rammed-earth walls, again in cooperation with Robert Felber. Horizontal cornices of fired clay slabs were inserted into the exterior walls at regular intervals to stop the flow of water. Between them, he rammed layers of trass chalk, able to repel water, into the walls.
This first house was a decisive project – not only for Rauch’s business, but also for earthen construction in general. A first large project with, in part, load-bearing walls was created for the zoo in Basel, the Etosha House (1998-99), in collaboration with the architect Peter Stiner. The decision to hire the builder of earthen structures, who was still working as an artist at the time, and to build with a largely unknown material testifies to the courage of the building contractor and the planner. Once finished, it became clear that both the building material and the builder were reliable.
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Source: Lehm Ton Erde Baukunst GmbH
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Source: peter bauerndick
With the next project, Rauch brought earthen construction to the attention of the international architectural community. For the Chapel of Reconciliation (1999-2000), the first public rammed-earth structure in Germany in 150 years, the architects Rudolf Reitermann and Peter Sassenroth, in cooperation with Rauch, developed an impressive building form that found new expression for the traditional building material. The oval layout presented the builder with new challenges, and the enormous lintel over the opening of the altar required a clever structural engineering solution. Rauch developed numerous details, and, with his team, also came up with methods for simplifying the fabrication. He used circular formwork, common in concrete construction, and the compacting of the material took place using vibration rollers usually employed in landscaping. It was in this sacred circle of rammed earth that Federal Chancellor Angela Merkel gave her official speech for the 30th anniversary of the fall of the Berlin Wall on 9 November 2019.
What followed was a series of projects with the architect Roger Boltshauser that brought rammed earth into the present. First, small buildings – a tool shed and a tower (2000-01) – were erected on the Sihlhölzli sports grounds in Zurich. Rauch’s house in Schlins (2005-08) and the Allenmoos school pavilion in Zurich (2011-12) were then also constructed. In these projects, Rauch’s experience as a craftsman came together with Boltshauser’s precise design. This combination gave rise to a fascinating unity of formal rigour and sensual materiality. The daring architecture entirely without an overhanging roof was a touchstone for the durability of the material. Rauch remembers the anxious period shortly after its creation: ‘After every downpour, I went onto the terrace and collected the earth that the rain had sluiced away. I then tried to forecast how long the wall would last. It didn’t look good. But, with time, the rain showers removed less and less material. It was apparent that only the outermost layers were washed away. The wall stabilised on its own.’
Vogt landschaftsarchitekten novartis campus martin rauch architectural review
Source: Christian Vogt
Allenmoos school boltshauser martin rauch architectural review
Source: Beat bÜhler
Other architecture firms then sounded out the possibilities of the material. Rauch was finally able to realise a project with the firm Herzog & de Meuron: the Ricola Herb Centre (2012). For Snøhetta, he was able to create a huge wall in the King Abdulaziz Center in Saudi Arabia (2010-14). In cooperation with the architects Martin Haas, David Cook and Stephan Zemmrich, prefabricated elements with core insulation were used for the first time for the Alnatura Campus in Darmstadt (2016-17). All of these were milestones for the formal and structural engineering development of rammed earth, but Rauch was also able to push forward the methods of fabrication. This is vital for the future viability of the material: if earthen construction is to keep pace with the tempo of a contemporary construction site, the production methods have to be altered fundamentally as well.
Compacting the material with machines saved a lot of time and effort. But, in an industrial-scale project like the one for Ricola, for example, creating the earthen walls in formwork was no longer conceivable – the other teams on site would have had to wait too long to progress the construction. Rauch accepted the challenge: ‘The time was ripe for earthen construction, but I had to keep pace with the progress in construction technology. That’s why we had to automate the process and reduce the amount of manual work. That was absolutely crucial to be able to build with earth on a large scale and thus remain competitive.’ For this project, Rauch leased a factory hall near the construction site and had a machine for the semi-automatic fabrication of earthen blocks produced: he called it Roberta. And Roberta fabricated long walls from which the earthen builders then cut individual blocks. The earthen blocks produced filled the entire industrial hall. They could be picked up, stacked on top of each other with a crane like gigantic building blocks, and be grouted with clay on site. Rammed earth had arrived in the present.
Swiss ornithological institute mzld architekten martin rauch architectural review
Source: Alexander Jaquemet
What sounds so simple was the result of huge efforts and a good measure of ingenuity. How can the blocks be lifted and transported without falling apart? How can the chain of production be realised so that it fits into the logistics of a construction site? Round windows also had to have a drip edge to prevent the erosion of the material, and, in connection with load-bearing capacity and food safety, a number of approvals had to be obtained. Formally, the result was an impressive new chapter for earth construction – with respect to fabrication, it signified nothing less than a quantum leap.
Rauch was able to use the manufacturing hall to produce the elements for Ricola in parallel with the Swiss Ornithological Institute (2013-14) by :mlzd Architekten, using prefabricated elements produced by Roberta. But, afterwards, no other projects followed, and the costs for the hall could no longer be met. Roberta was taken apart, stored, and sent into hibernation. Rauch was now faced with a dilemma: what should he do with the knowledge he had acquired? How could this experience and the compacting machine be used for other projects?
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‘Not every project is big enough to set up a production site specifically for it’, Rauch stated. ‘For Ricola and the Ornithological Institute, we were able to use the hall, and, in Saudi Arabia, we were able to set up machine-supported production on site. But most projects cannot be realised economically with their own infrastructure.’ So Rauch turned the tables and developed a project for a new, larger workshop in Schlins, which began construction in May 2019. He has persevered with his path of experimentation: this hall is the site of structural engineering innovations for earthen structures. This time, the innovation is the load-bearing capacity of the material. The exterior walls support not only the substantial wooden structure for the ceiling, but also the track on which the heavy-duty crane that carries the heavy earthen blocks runs. Rauch once again broke new ground – the walls of preceding rammed-earth projects rarely supported anything more than themselves. With this project, Rauch showed that earth can be used as part of the structure – and in the process has given Roberta a new home and a fixed workplace.
Rauch is pushing the structural engineering limits of earthen construction by offering evidence through building – but, in his mind, there do not seem to be any limits for this material. ‘My vision is entire cities of earth and multi-storey residential buildings that provide a wonderful indoor climate with a small ecological footprint. There’s enough material to do so, and it would also be a fascinating story with respect to form’, Rauch rhapsodises about the future of the construction method that he saved from extinction. There are already sufficient examples of this in the history of earthen construction – but, perhaps, the pioneer is once again ahead of his time. Translated by Amy Klement
Martin rauch rammed earth fabrication architectural review 05
Source: Hanno Mackowitz
Martin rauch rammed earth fabrication architectural review 04
Source: Hanno Mackowitz
Designed in close collaboration with the architect Roger Boltshauser, Rauch House overlooks the village of Schlins, Vorarlberg, in Austria. Many technical aspects were without precedent, so involved an ongoing process of experimentation between the collaborators. The house is nestled in the hillside, made from earth excavated from the site on which it stands, and gestures towards the valley with shifting blocks and generous openings.
It is clear that the house is an exercise in practising Rauch’s proclamation that he wants to ‘build contemporary forms’. The rhythm of the exterior is defined by erosion checks – clay bricks entirely handmade by Rauch that serve to slow the flow of water on the surface of the building. The successive bricks surface as horizontal stripes with a crayon-like line that has a softness which surrenders to the character of the rammed-earth walls they sit amid. This spirit is not lost in the interior either, and the haptic qualities of the earth are emphasised in the oval space enclosing the staircase. Moving through the building means ascending through this dramatic vertical tunnel of clay. There is a pleasant balance to the building. Living needs are gently taken care of within the constraints of the rectangular volume.
A clarity and sharpness characterises the form, and the gleaming white-clay and quartz sand lining of the interior spaces produce sleek rooms within which to view the adjacent expansive landscape. The increasing level of refinement at play throughout the building, from silken surfaces, to handmade tiles, to exposed coarse clay, confidently tells the story of transformation that is at the core of the project, and indeed much of Rauch’s oeuvre.
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Source: Beat Bühler
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Ricola Herb Centre is one of several buildings Herzog & de Meuron have produced for the Swiss herbal sweet manufacturer. Appearing as a monolith among flowering meadows, as if it were itself a monumental single earthen block, the industrial facility was designed to cater for the processing of herbs in-house, on one site. Generously sized interiors accommodate the space required for the movement of vast industrial material and machines, and the elongated rectangular form hints at a linearity that might describe the production process – drying, cutting, blending, storing herbs – that is central to the work of Ricola. At 11 metres high, 111 metres long and 29 metres wide, it has an obvious presence amid the open fields, and the bulkiness of the earthen walls is exaggerated by the short protruding strip of wrinkled roof.
The intelligent positioning of openings is crucial in rammed-earth construction, and circular apertures that punctuate each wall have a substantial 5-metre radius that differs from the conventional language of earth buildings. The scale of the building demanded a construction process more efficient than the creation of labour-intensive formwork, and the semi-automatic method of fabrication Rauch developed made it possible to assemble 666 stackable blocks of rammed earth within five months. Clay has been extracted from the area surrounding Laufen for thousands of years, and the properties of the material are well suited to the specific humidity and temperature the herb production requires. The sand, clay and gravel used in the walls was sourced from local quarries within an 8 to 10 kilometre radius, tying the building to the landscape on which it is built.
Ricola herb centre detail herzog de meuron martin rauch
Ricola herb factory martin rauch herzog de meuron architectural review
Source: Benedikt Redmann
This project is a crypt for a late-Gothic church in Sülchen, Rottenburg. The use of compacted earth for a subterranean burial chamber is a fitting, if obvious, reference to the nature of a permanent resting place – underground, hidden, a return to soil. Sequences of rooms appear as if carved out, convincing in their evocation of early rock-cut tombs, and the inner earthen lining presents its layered character like natural sedimentary rock. There is a clear spatial order, and the church’s axial symmetry is used fluently in the newly designed spaces. Movement is gently directed by two parallel stairs which descend to the level of the oratory. The central room has a lofty height and the episcopal tombs with their slate grave slabs are stacked on two levels on either side, a reminder that there is ultimately a practical purpose at the core of a crypt. The minimal altar block, the focal point of the oratory, is made from travertine. Its simple form complements the precision of the rest of the crypt.
During the process of excavation for the addition of the burial chamber, pre-Romanesque foundations were discovered beneath the church, as well as elements of construction from the sixth or seventh century. These are enclosed for display in a room under the apse, and a compacted earthen wall of the new burial chamber addresses one side. Exhibition cases displaying smaller objects of funeral culture are tucked either side of the stairs. There is a neatness to the solidity of the spaces, and the qualities of the loam walls and floors – cool, soft, faint, muted – invoke a calmness that is commensurate to the inner contemplation implicit in a sacred space designed to remind us of our mortality.
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Burial vault bishops rottenburg cukrowicz nachbaur martin rauch architectural review 02
Source: Emmanuel Dorsaz / Lehm Ton Erde Baukunst GmbH
Lead image: Martin Rauch, photographed by Markus Bühler
This piece is featured in the AR February 2020 issue on Soil – click here to buy your copy today