Conservation actions often challenge traditional planned conservation tools, especially when referring to the management of data relating to the existing building heritage due to the huge amount of information to be acquired and archived. In response to this requirement, the Building Information Modelling (BIM) process, applied to historical buildings as Historical-BIM (HBIM), could be an effective solution for integrating different types of data concerning not only the geometric features but also useful qualitative information in conservation and preservation works (i.e. the type of materials, construction techniques, the presence of degradation and instability, intervention techniques, etc.). Although the BIM process has reached a considerable level of maturity, several aspects related to the application of the method to existing structures through the Scan-to-BIM process require further research; particularly the need to find suitable approaches to integrate, manage and store thematic information. The article describes the work carried out in the case study of Villa Castelnuovo, an eighteenth-century architectural building located in Palermo (Italy), in which, starting from an integrated survey, it was possible to generate an HBIM model to support all the phases concerning preventive maintenance, long-term redevelopment and management of the architectural asset. The research focused mainly on the modelling and information integration phases, developing a procedure applicable to different contexts for storing, managing and analysing the external façade decay necessary for documenting and monitoring the architectural heritage.