IRT Survey of Historic Building Façades for Focusing the Diagnostic Analysis

In the framework of conservation of historical buildings, the infrared thermography (IRT) is a valuable tool for the image diagnostic on façades. This non-destructive technique allows to discover structural defects on masonries—such as detachments, cracks, inhomogeneity in the wall texture, or to determine heat dispersion, raising dampness, and water infiltrations—by the detection of the surface temperature. In the present work, the IRT technique was applied to investigate the painted façades of the Lenzi palace in Florence. The palace currently houses the French Institute in Florence and it has undergone several renovations and restorations over the years, the last one in 1984. The target of the IRT survey has been to highlight the areas affected by decay phenomena, including those already restored. This result was used to direct the sampling for the laboratory analysis, thus reducing the number of samples and optimizing the sampling procedure. The laboratory analysis, consisting of FT-IR, XRD, optical and electronic microscopes investigations, allowed the identification of the executive technique, the products of past restoration and the alteration/decay products. Through the experience of the case study of palazzo Lenzi, it was possible to check the effectiveness of the IRT technique in supporting a multi-disciplinary approach to focus the diagnostic analysis and verify the efficacy and duration of conservation interventions by remote way identifying areas subject to new degradation phenomena.