Experience has taught us, for millennia, that we should reuse material, and we can see examples of this in clothing, furniture, or building materials. But the “modern man”, as each generation likes to call itself, often forgets it, in the sense of breaking up with the past, as a rupture is one of the forms of human evolution, of the scientific revolution, in a paradigm shift as defined by Thomas Khun. At present, when the finiteness of the planet's resources is no longer an isolated concern and has taken over political agendas and citizen action, we know that new paradigm shifts are needed in many human activities, with architecture and construction being one of the most important. The reuse—of material, components, and entire buildings—should be a mainstream choice, focusing on preserving our heritage in a broader sense: constructive cultures, material resources, and the natural and built environment. This paper will present an ongoing experiment in reusing materials and components in an intervention on a family rural house built between the eighteenth and twentieth centuries in a village in Minho, Portugal. The narrative aims to question assumptions, processes, and difficulties, analyzing the design method when material existence and conservation principles drive the project development. The case study analysis will be cross-referenced with the inventory process of identifying existing components and where to buy used components, which is crucial to the advocated paradigm shift.