Materiali e progetto. Compatibilità e durabilità negli interventi di recupero e di restauro

Materials and project. Suitability and durability in recovery and restoration interventions. By addressing a special issue as one that include the relationship between “materials” and “project”, the goal is to address the issue of historical heritage recovery and valorization; it could be a “prototype” and model of interventions that are reproducible in all those town centres with has significant monumental, architectural and environmental features. The debate on intervention methodology (that in the past was mainly based on its effectiveness), after decades of application, tests and verification, has been enriched by a new topic: the physical, chemical and structural “suitability” between new materials (and technology, as well) and built heritage. In fact, any procedure and technique in recovery and restoration of built heritage can not ignore the knowledge of materials and constructive technology used for the construction of a building. The main problem in recovery interventions is to reconcile the different construction techniques and the 256 different materials (sometimes incompatible with the built heritage), and - more importantly - to relate the materials and technologies used in the “new” structures, in the “old” or “historical” ones, regardless of the inappropriate choices, disrespectful of static-functional-formal-chemical and physical balance well-established over the years. These days, rehabilitation is one of the central issues in architecture. To refurbish is to explore the intervention options for transforming the existing built heritage; this is accomplished by identifying and defining the interrelated and complex relationships between the building and the overall environmental system. Only by determining the environmental constraints and the degree of freedom allowed by preservation theory is it possible to arrive at a rehabilitation approach which operates as a balanced synthesis in the relationship between preservation, transformation, and use. It seems necessary, therefore, to develop a more technological, design, and production-based strategy to help define the different intervention options. In other words, it is important to create a situation where the rehabilitation work operates systemically, taking into account the technical and cultural variables to provide a balanced framework that incorporates both preservation and transformation decisions and procedures. “To preserve means to use”: this assertion is the basic prerequisite and underlying premise of the modern theory of architectural heritage preservation. Given the truth of this assertion, one can conclude that these days, rehabilitation - whether for a single artistic/historic artefact or the built fabric of an entire historic centre - could and indeed has to be carried out based on a profound technical-scientific understanding, as well as an analysis of their inherent value, so as to satisfy the functional performance, and use requirements of the user the ultimate validation of the choices made. This inevitably triggers a new approach to analysing the historic-architectural and/or urban heritage where it becomes necessary to define not only the preservation and transmission issues but also those related to future appreciation. Taken in this light, rehabilitation is a “cultural act” (with a historical-critical and scientific-technical basis) which is taken in its broadest sense to mean “integrated rehabilitation”, i.e. open to the logic of use and re-use, material and technological requirements, planning-zoning and regional issues, as well as ecological and environmental ones. Preservation is never “pure preservation” but always a kind of “controlled transformation” [cfr. Benevolo]. Here the term transformation is used to mean a more appropriate and flexible process designed to bring the architecture closer to the needs of free use. Preserving and appreciating the identity of a work of architecture is no longer merely an abstract goal; it has now become a matter of very practical self-interest. This is because the work’s uniqueness, history, and culture, give added value to the purposes for which it is “used” and reused”. When dealing with a deteriorated monument/asset, the designer essentially has to respond to three questions: “if”, “where”, and “how” to go about the rehabilitation. To these we can add at the most one more, one where the financial aspect plays a large role: that is “when” to go about the rehabilitation. To answer these questions fully, further information needs to be obtained via easily definable procedures. This required information includes: the nature and cause of the deterioration, safety assessment, need assessment, rehabilitation potential, and finally the choice of the optimal intervention strategy and definition of implementation methods. Choosing the “appropriate” intervention: This phase includes the selection of intervention techniques, their execution, the scheduling of periodic inspections, and the restoration test. The key elements impacting the choice of intervention type include: analysis of possible technical solutions based on the asset’s deterioration; structural and performance requirements; and the aesthetic, functional, and financial aspects of the solution as they relate to the cost, work time, and maintenance. The specific techniques used to counteract the effects of deterioration can be broadly considered in two categories: the first has to do with interventions for restoring or improving the deteriorated materials, and 257 preserving the existing structures and their functions intact; the second, however, has to do with interventions which involve inserting a new load bearing structure alongside the existing which works in parallel to a varying extent up to the point of even completely replacing the load bearing function of the original structure. If “rehabilitation” is understood to mean attaching a “value” to an object, then “to rehabilitate” means above all to decide that the object “matters” even if it is significantly compromised. Rehabilitation is based on certain fundamental concepts which form the basis of its guiding principles. First of all, there is the concept of “stewardship”; this is understood as watching over something in order to save it. However, it also means any protective measure that does not involve taking direction action upon the object itself. Then, there is the concept of “preservation”; this constitutes a legal action of protecting an object or collective resource from damage, without which it would be exposed to deterioration and even extinction. So, the fundamental notion of preservation should be understood as saving an asset from deterioration and from the effects of time, accidents, mistakes, wrong restorations, etc. Finally, there is “appreciation” which means a process, an action, or a series of actions which increases the value of the asset’s components or elements. Importantly, appreciation does not add value, but rather makes the existing value evident. The latest methodology guidelines consider “integrated preservation” to be the goal. “Integrated preservation” is understood as “the result of the combined action of restoration and the assigning of appropriate functions.” Integrated preservation is not a static condition; instead, it is a dynamic and integrated approach to building for the future in a compatible and balanced way, one which operates within the general tendency towards the global development of society, in alignment with the fundamental cultural values of our time. These days, the integrated use of traditional and contemporary technology seems to be the only workable way to ensure the appropriate level of preservation and the right scholarly approach to a cultural asset. These days, re-use/rehabilitation is closely connected to a design synthesis that relies heavily on preservation rationale while opening the door to a new architectural language of “making”, that of rewriting the present by coherently modifying the past.