Technical and technological qualification of ancient buildings. The case of churches in " Sassi di Matera "

It is widely recognized that historic buildings conservation cannot leave out the knowledge of its constitutive features such as: materials, constructive techniques, structural characteristics and building evolution. Thus, the preliminary phase of data acquisition represents a crucial point of the designing process, that has to begin from direct recognition of the building characteristics with a survey of the observed alterations, and supported by the historical documentation (bibliographic and/or archival). The "critical" synthesis between these two aspects of the cognitive process (i.e. direct knowledge and historical analysis) is the essential condition for designing a "congruent" restoration intervention, that is, a restoration capable of synthesizing the dichotomous relationship among technical and philological issues. This methodological approach is presented and applied in this paper to different case studies belonging to the churches typology of the Sassi di Matera UNESCO site in Southern Italy. The chosen cases differ completely for age, peculiar characteristics, shape and dimensions. Then, the case studies are evaluated with simplified procedures for seismic risk assessment, which have allowed us to draw the first conclusions in terms of the diagnosis that will lead to determining the restoration approach.