Analysis of red stains on building facades in Bahia – Brazil

Abstract The facades are essential constructive elements to the performance of buildings, because they influence in several characteristics such as the protection of the internal environment from external aggressive agents, such as temperature variation, winds, precipitations and humidity. Due to their high exposure to the environment they become more vulnerable structures to the appearance of pathological manifestations, which consequently contribute to an accelerated degradation process. The red stains are a type of pathological manifestation that occur in facades and portray the accumulation of microorganisms on the substrate of the seals that lead to the formation of biofilm in the red color. The objective of this work is to analyze the red stains on building facades in relation to the geographic orientation, vertical distribution of the stains on the surface of the facades, distance from the sea, and the surroundings of the buildings. For the development of the research, a data survey of nine buildings in the city of Salvador-Bahia and the Metropolitan Region was carried out. As main results, it was obtained that: the south-facing façades tend to be more affected by the red stains due to the higher humidity when compared to the others; there is a tendency in the concentration of stains in the upper region of the vertical plane of the façades; it was not found a correlation of the distance from the sea influencing the dissemination of the stains and buildings whose surroundings have a higher incidence of vegetation cover presented a higher proliferation of stains in their surroundings.