NDT applied to the diagnosis of historic buildings: a case history

Recently, Villa Litta Modignani, a XIV century country palace near Milan, was intensively studied by the authors in view of the design the preservation intervention. The building is affected by a variety of decay problems. Most of them can be detected by visual inspection of the decay effects and do not need direct ND investigations. Nevertheless, the design of the repair interventions must be approached only after that a deep knowledge of the material and construction techniques has been obtained. This goal is the motivation of most of the ND investigations (radar, thermovision, ultrasonic test, etc.) that were performed on the building. Four main issues were defined: morphology and detection of hidden reinforcements in the vault structures, detection of voids in the load bearing walls, timber beam position and connections with the walls, material and construction techniques of columns. For each of these main issues the most convenient ND methods were selected by considering their technical potential but also their costs and the specific access conditions (e.g., no scaffoldings were available at the time of the investigations). Thus, an intensive use of thermovision was done whereas georadar was often used on the floor or on structural elements that could be easily reached. Sonic measurements were performed on the columns.