The prefabricated earth elements are manufactured in a nearby factory out of ingredients extracted from local quarries and mines. Clay, marl and material excavated on site are mixed and compacted in a formwork and then layered in blocks to build the walls. Thanks to the plasticity of the loam, the seams can be retouched giving the overall structure a homogeneous appearance. To arrest erosion caused by wind and rain, a trass mortar achieved mixing volcanic tuff (trass) with lime, is compacted every 8 layers of earth directly in the formwork.