The University of Nantes has developed a 3D printing technique (BatiPrint3D TM) dedicated to the construction of the walls of a house. This innovative on site construction technique is based on the deposition of two layers of expansive foam used as a formwork for a third concrete layer. It allows to build at the same time the structure and the insulation. This new construction technology has first been developed at the laboratory, but rapidly, we decided to deploy it on site, in order to demonstrate its technical viability. We present the technology Batiprint3D TM and the demonstrator Yhnova TM , a 95m² social dwelling built for the social landlord Nantes Métropole Habitat (NMH).