In this book, together with Pierre Chabard, Philippe Vander Maren and Richard Venlet explore and explicit the design process of House D through a set of unpublished work documents such as sketches, scale models, series of annotated plans, collages and pictures. They retrace the collaboration with the client, the exchanges between the architect and the artist, the moments of discovery of essential features of the design, the similarities and dissonances with architectural precedents. This book was produced following the In Practice conference in Liège, Galerie Opéra, on June 12th 2018. In Practice is an initiative of Harold Fallon (KU Leuven) and Benoît Vandenbulcke (ULiège). Initially, In Practice were conferences at which architects were invited to unveil their working documents and tell their story. These short conferences were followed by a conversation with a panel of critics, architects, editors and academics. Architecture opened up to the modalities of research.With this book, In Practice goes further and positions itself at the heart of research, while remaining at the heart of the architect’s work. The book is written on the basis of collected statements. Or rather, it is written by many hands: the external outlook and inner knowledge complement each other. The work dissects the genesis of a project, it shares the doubts, it extracts the mechanisms that lead to choices and it discovers the intuitions which make poetry.