As a part-time collaborator for the architectural offices architecten jan devylder inge vinck and AgwA, I have been involved for four years in the refurbishment of the Palais des Expositions of Charleroi, a post-industrial city in the south of Belgium. In my other part-time, I am a doctoral student in architectural history. In line with this situation, the article is divided in two. First, I develop a reading of the construction site based on the concept of “externalities” borrowed from environmental humanities, a disciplinary field that I explore in the context of my research. Secondly, I re-use this conceptual framework to describe the development process of the project, during which I have noticed that some decisions were consciously outsourced. By interpreting this observation, by linking it to my reading of the construction site, I seek to open the debate on the posture of the architect in a contemporary post-growth context.