Restoration Theory and Practice of the Compagnonnage du Devoir. The fabric integrations in the Tour St.Jacques in Paris

Restoration Theory and practice of the Compagnons du Devoir. The fabric integrations in the Tour Saint-Jacques in Paris 1. Introduction This paper reports research underway since long at the ICAR Department of the Faculty of Architecture of the Polytechnic of Bari on the building and restoration of cut-stone work in the theory and practice of the French Tailleurs de Pierres. The awareness that architecture, differently from other arts, is the synthesis of three meanings, formal, structural and functional, has lead us to consider the construction as an overall value encompassing both the project and the restoration of cut-stone work. Namely, in restoration one of the critical issues is the discrimination between the formal and material values, which is needed to establish the limits of the intervention. Although, as Brandi says, it is possible to restore only the matter of the work of art (architecture), in the case of stereotomic architectures, where matter cannot be separated from image, the form cannot be separated from the structure as it is co-substantial, it is more difficult to choose the intervention better suiting the need to transmit the "image" . In France, where stereotomy was born and the cut-stone heritage is largely spread, restoration is regarded as wise “maintenance”, thus interpreting in a positive and constructive way the principles of article 4) of the Venice Chart of 1964. The distinction between matter and overall unity underlies the choice of the method and the identification of the intervention techniques by the Compagnons du Devoir, aiming to enhancing the formal unity over the conservation of the matter. The methodological analysis of a case study such as the restoration of Tour Saint-Jacques in Paris shows how constant maintenance can enhance the value and the persistence of architecture and its meaning as an organism. In the experience of the Compagnons du Devoir, the continuous substitution of the “rotten” matter becomes an extraordinary means of knowledge of the techniques, a transfer of know-how and primarily the unitary transmission of the architectural image of the historical heritage. 2. Theoretical principles. Integration vs Conservation The principle of conservation implies that the degree of modification of the work when it reaches us is a value in itself as part of history; conservation often involves the use of chemical agents to “mummify” pieces of architecture in their present situation, thus avoiding to take any critical cultural position on events regarded as meaningful. Conservation suits remains and works which are inherited from a past era and which we choose to preserve as they are for cultural reasons. Integration implies the knowledge of the wealth of historical notions, of the construction techniques, structural modes and static behaviour of the architectural structures. In order to act in full compliance with the structural organism and revise ancient, though not obsolete, techniques and concepts one needs to master anew the traditional intervention techniques based on disassembling and assembling, partial replacements, new wall textures, wise remakes of wooden and brick structures if these show decay or are damaged following an earthquake or a war. Disassembling, remaking and assembling bring about a process of knowledge and transmission of knowledge and know-how, which is indispensable to the continuity of the building tradition. 3. Tour Saint-Jacques building integration The case under study is the restoration of Tour Saint-Jacques-de-la-Boucherie, erected between 1508 and 1522. The restoration intervention is aimed on the one side to preserve and consolidate as far as possible the architectural and sculptural elements of the decoration, by recording them with a 3D laser scanner in the state of decay in order to build a database for future use. The goal of formal unity is attained through the knowledge and geometrical description of the décor elements to be replicated and reintegrated, by avoiding to use heteronymous material, such as resins and cement, which can only serve as support to incoherent ruins. 4. Conclusion The restoration of a historical cut-stone building meant as maintenance of its formal integrity is implemented through the replacement and integration of missing or highly deteriorated parts and acquires a two-fold value. On the one side this approach, constantly implemented in time, assures the persistence of the formal unity of an architectural body and its liveliness; on the other it assures the continuity of an operative tradition, the updating of stereotomic know-how and thus the opportunity to intervene in the future with the same updated know-how on cut-stone buildings.