Allowable temperature conditions for hydration processes of the majority hydraulic binders are in the range (+5... +30)°C. That is why temperature is important for work with ETICS - external thermal insulation composite systems. Period with an average daily outdoor temperature +5°C is quite arbitrary, because temperature can drop below the limit value in the night and unpredictable frosts promote the risk of slowdown (or termination) of hydration processes of hydraulic binders in the fresh plaster. For the qualitative risk assessment of the operational properties reduction for plaster layers of walling, in this paper a full-scale laboratory simulation of the production of ETICS in conditions of unstable diurnal fluctuations in air temperature was conducted using a mobile stand for facades trials. According to the test results, a significant degradation in major performance in the case of daily fluctuations in air temperature below +5°C was determined.