Architectural stucco carvings suffer from many aspects of deterioration due to environmental corrosion factors, especially moisture. Moisture is the key factor for the establishment and spread of fungi within the stucco granules, and it leads to the surface decomposition and fall of the stucco surface parts near the end of the incubation period. Analyses and investigations have been conducted on the stucco material, including XRD and ESEM-EDX analyses. As the main stucco component, Gypsum is occasionally replaced with a Hemi-hydrated phase, such as bassanite in one sample, in addition to traces of halite, calcite and silicates. Relative humidity, temperature and fungal infection were monitored to assess their interrelationship and impact on stucco deterioration. Isolated fungi were identified and tested for their ability to grow on mockups with the same components of examined archaeological stucco. Eventually, moisture and salinity are expected to activate specific physical and chemical reactions and fungal growth, which facilitate dullness, brownness, blackness and the biodeterioration of stucco surfaces.