Effect of Water on the Degradation of Gypsum Plaster Coatings: Inspection, Diagnosis, and Repair

This paper presents an expert system designed to support the inspection and diagnosis of gypsum plaster coatings applied to partition walls and ceilings [interior gypsum plaster (IGP)]. It includes a classification of the defects that may affect IGP and their probable causes, the correlation matrices amongst defects and between defects and probable causes, and a classification of diagnostic methods and repair techniques suitable for each type of IGP defect. This inspection system was validated through standard IGP inspections undertaken on 119 walls or ceilings in 23 buildings located throughout Portugal. A statistical analysis of the results of the inspection is given that provides details on, in particular, the pathological problems related to the action of water on IGP because the presence of moisture within or on the surface of IGP coatings was shown to affect the severity of the problems of inspected samples. The characteristics and frequency of occurrence of dampness, biodeterioration, and efflorescence and cryptoflorescence are presented, together with the primary causes for their presence in the sample. The most suitable diagnostic methods, preventive measures, and repair solutions prescribed for these defects are also analyzed, in detail.