Moisture in historical buildings from causes to the application of specific diagnostic methodologies

The moisture in masonries is one of the main responsible for the deterioration of historical buildings. Moisture increases U-values, weakens the structure, damages the surfaces and, finally, promotes the growth of fungi and moulds which reduce the Indoor Air Quality and can affect the artefacts, when present. Several factors contribute to this phenomenon: accidents (burst of pipes and ducts), design errors in the restoration of an ancient building (superficial and interstitial condensation), geotechnical factors (e.g., rising damp, presence of embankments), the degradation of materials promoted by rainwater infiltrations and the construction techniques (e.g., preparation of mortars and plasters during construction/restoration works). However, intervention strategies require the correct qualitative and quantitative identification of the cause of the presence of moisture. This paper deals with the objective diagnosis of the presence of humidity in masonries. After an overview of the main causes of the phenomenon, and related strategies of intervention, an objective diagnostic methodology is presented and described. The methodology has been designed for rising damp and it is also suitable in the case of other causes of humidity (e.g., soil moisture, accidental moisture, condensation, etc.). Finally, a case study focused on the diagnosis and planning of the restoration of a building of great historical interest has been analysed.