Thanks to the renewal of construction history and building archaeology these past decades, it is now well admitted that reuse of construction materials has been a widely spread practice through every times and cultures. By exploring the great variety of actors, technics, meanings and even economical purposes behind this one idea of “reuse”, it has become obvious that specific contexts of each case of salvage and reuse have greatly shaped the architectural projects and economic landscape of the building site. Considering particularly the medieval and early modern periods in France, this paper proposes a survey on a particular context for the builders: the times of crisis. Human or natural catastrophes have deeply affected the domain of the construction—either beforehand, during or afterwards the events—with a recurring sense of urgency. From tough times to open wars, shortages or price inflation of building materials, budgets’ decreases, cuts in provisioning networks, etc. have disrupted routines in construction works thus leading to reuse practices that did not exist before. In the end, the crises have also produced an amount of ruins, fragments, rubble that has to be removed for the life to go on. From cleaning a place to restore confidence, memory and heritage, dealing with the aftermath eventually imply another range of reuse practices.