Earth-based building materials provide a pathway to mitigate the carbon footprint of the construction sector. The use of these materials is still nowadays limited because of their weak mechanical properties, high shrinkage and the time required for drying. This paper proposes to investigate the synergic approach which consists in coupling a 3D printed earth-based open matrix core wall system to a hygroscopic insulation material: moisture transport from this hygroscopic insulation material to earth-based printed material aims to reduce the amount of water entrapped into the printed soil, and thus increase the drying rate of the earth and its so-called ‘buildability’ property at the same time. A choice has been made to focus in this study on a matrix core insulated wall system composed of clay as printed material and on wood fibers as hygroscopic insulation material. Apart from the service-life properties provided by the coupling of both materials, this work mainly aims to assess, first and foremost, the potential of dry wood fibers filling to stiffen printed soil-based structure during 3D printing process.