Stratigraphy and analysis of interfaces for the preservation of architectural heritage

The study contributes to the recognition of the central role of the interface in a restoration project. In fact, boundaries, joints and connections represent the key factor for understanding and interpreting the chronological sequence of the construction in a historical monument and they are the place where the contact of different entities can engender problems of connection and transmission, as well as material, chemical–physical, aesthetic or related to technological compatibility (structural, thermic and hygrometric). In the planning stage, they also intervene decisively in the principles of feasibility such as distinctness, reversibility, current expression and sustainability, which form the theoretical basis of the discipline. One particular case of interface is the one generated by erosion. The text presents the case of erosion of the urban walls of Cagliari, where the phenomenon has been faced by the creation of interesting integration interfaces in the course of time. Particularly, in the case of the ‘Porta di Altamira’, a scale of the degrees of erosion, useful for the planning of possible units of integration, has been studied. Based on the case study and the theoretical principles of the discipline, the research suggests the stratigraphic process as a standard methodology and operating criterion for the preservation and the restoration of interfaces and for the integration of gaps.