Cob building is a historical, originally rural, shuttering-free construction method. This technique has become widespread all over Europe in areas with local clay deposits. Traditionally, cob (loam reinforced with straw) is laid down manually in layers. The layers are left to set for a few days. Afterwards, they are manually reworked and straightened by cutting them with a sharp spade.
Weller clay, which was displaced by concrete in the 20th century, can be shaped into any form for vertical structures – similar to concrete. It is self-supporting and erosion-resistant without plaster.
The construction method has a high innovation potential. Together with an international research team, we are developing a process that can be used on an industrial scale to help Wellerlehm achieve a breakthrough as a building material for load-bearing walls.
Our concept combines immense economic and ecological advantages:
- Recycling capability
Unlike concrete, clay can simply be levelled on site in the event of deconstruction or reused for the next building project. Since it does not require any stabilising additives, it is 100% recyclable.
Furthermore, earthen buildings have a much longer lifespan (hundreds of years) than conventional buildings.
Our process achieves a high compressive strength. It enables the construction of load-bearing walls from excavated soil taken directly from the site and mixed with straw. This can be compacted according to our recipe. We are thus opening up a construction method whose material is available (almost) everywhere and can be implemented on a large scale in the future.
- Indoor climate
Solid earth buildings, as in the case of cob, are unrivalled in their ability to regulate humidity and heat in their
regulating the indoor climate and comfort.
- CO² neutrality
Our concept is to work with local loam, i.e. with excavated soil and straw from the respective region. This means that only the energy required for mixing and processing is used in the production of the building material.
- Nature conservation
Wellerlehm provides shelter for particularly protected wild bee species.
Figure: Shortly after completion of a test wall in Nebelin, it has already been colonised by wild bees. Photo Dr Dieter Günnewig, July 2020.