Documentare per valutare: La qualità del progetto sulle superfici dell'architettura storica

The quality of intervention projects on historic architectural surfaces represents a relevant and timely issue, considering the significant impact of such works within Italian historic centres. Although difficult to quantify objectively, this parameter is closely related to the relationship between knowledge, project, and execution according to UNI 11897:2023. This relationship depends on reliable documentation concerning the material transformations of architectural surfaces over time. In this perspective, documentation becomes a critical act aimed at preserving the material authenticity of architecture. Without accessible and comprehensive documentation, each intervention risks remaining an isolated episode, difficult to assess over time for effectiveness, compatibility, or reversibility. International Restoration Charters have repeatedly emphasised the need to document the ante operam, in progress, and post operam phases, recognising documentation as a fundamental tool not only for administrative purposes but also for knowledge and conservation. Nevertheless, in current practice, this requirement is often disregarded, particularly in relation to widespread historic built heritage, resulting in the loss of essential information for ex post evaluation and for constructing a shared memory of conservation works. To guide and regulate interventions on architectural surfaces – often associated with routine maintenance – this field should be structured through procedural protocols that define project criteria and support more consistent conservation practices. The paper presents a critical reflection on these issues and discusses a procedural protocol inspired by the assessment structure of DNSH, aimed at preserving and organising documentation on interventions on historic exterior surfaces and supporting an explicit, verifiable evaluation of project quality through the correlation of preliminary knowledge, project choices, operational phases, and ex post assessment within a coherent conservation framework.