Dipl.-Ing. Ulrich Röhlen is an architect and technical director of the earth building materials manufacturer Claytec e.K.. He is a board member of the Dachverband Lehm e.V., the German Association for Building with Earth and co-author of the “Lehmbau Regeln”, the German building codes for earth construction.
Dr.‑Ing. Christof Ziegert is an accredited consulting engineer and surveyor of “damages to earth constructions”. He is a partner in the office ZRS Ziegert | Roswag | Seiler Architects and Engineers which specialises in the planning and renovation of earth constructions, and a board member of the Dachverband Lehm e.V., the German Association for Building with Earth. He is a co-author of the draft norms for earth building in Germany and also lectures at universities, universities of applied sciences and vocational training institutes.