Methodology for Quantification of Staining in Historical Facades

The conservation conditions of historic buildings are fundamental to preserving them and mitigating their degradation. Environmental conditions of exposure can favor the appearance of pathological manifestations, such as staining, humidity problems, and the formation of organic matter, situations commonly found in facades. Although the influences of these phenomena are climatic conditions, characteristics of the surroundings, and constructive details present in the facades. In this context, this work aims to develop a methodology to quantify the stains on historical facades, correlating it to their geographical orientation. For that, we analyzed twenty buildings inventoried by the historical patrimony of the city of Pelotas, RS, Brazil. Images of these facades were taken through Google Street View and then staining was quantified using Adobe Photoshop CC software, using controlled tolerances. Data analysis showed that the geographic position significantly influences the staining, and the southern orientation presented the highest percentage of this degradation. Regarding the constructive details, it was identified that the stain occurs mainly in the upper areas of the facades, in plaques and cornices. Finally, the method developed was adequate for the analysis of facade staining, having similar aspects already used in works of several areas and it is possible to be replicated. This method can be useful to identify patrons and to turn possible preventive maintenance to preserve the historical patrimony.