Control of biodeterioration in urban walls

The biodegradation is a natural action carried out by active organisms, and this is not only unavoidable but it represents a fundamental process of every ecosystem. When this process is acting on « valuable » objects, is named as Biodeterioration and it is particularly unfavourable when the object belongs to the Cultural Heritage field. Climatic factors (temperature, humidity, rain, sun exposure, and air pollutants) can establish favourable conditions for the development of several organisms on the surfaces, inducing first of all aesthetic damages (vegetative structures, coloured patches or patinas and crusts). Different approaches have been adopted to isolate, identify and quantify such wide group of organisms, and several methodologies and products have been used to eliminate and prevent such biological settlements. Structures, like the urban walls, placed in the open are more susceptible to attack by these organisms, pollution and vandalism. A multidisciplinary operation needs to ensure the longest possible recovery work. As part of this operation, the control of biodeteriogens and their negative effects on the walls is a complex problem of which the agronomic question is only one of the important components. The exact knowledge of the resistance of a monumental object is crucial for a suitable schedule maintenance. Taking into consideration that the process can never be stopped but only slowed down to a minimum with balanced prevention and intervention actions.