This paper discusses different ways in which the term ‘hairy’ can serve to describe a building. ‘Hairy’ first refers to the peculiar texture of the hemp-lime covering a pavilion built near Antwerp by BC architects & studies. As an aesthetic feature of the building, it points to the first question I want to address in this text, which is the kind of aesthetics architects choose to adopt when advocating the use of ecological materials. In the second part of my argument, I explore how ‘hairy’ can also be understood in a more figurative way, when it suggests that the choice of these materials also come entangled with various environmental, social and political concerns. These two interconnected meanings of the term ‘hairy’ allow me to highlight the role that materials can play in binding together aesthetic and ecological concerns in the field of architecture.