Effects of Ageing and Moisture on Thermal Performance of ETICS Cladding

Herein we present the results of an experimental activity to assess the degradation evolution and the loss in hygrothermal performances of External Thermal Insulation Composite Systems with rendering (ETICS). We exposed to accelerated ageing a sample of ETICS (with vinyl resin added base coat and acrylic thick finishing coat onto expanded polystyrene) applied to a masonry wall. The sample was aged with a repetition of two macro-cycles consisting of 125 UV cycles, 125 summer thermal shock cycles, 50 winter thermal shock and freeze–thaw cycles. To assess the hygrothermal performances over time, we measured the thermal transmittance and the time shift when exposed to sinusoidal forcing, while degradation was surveyed with photographs at fixed positions. We note that, with ageing, the studied building component offered higher water absorption capability and, thus, the thermal resistance presented a decreasing trend, while an increasing trend was observed for heat capacity, and time shift. With regard to the evolution of degradation, we observed a very strong influence of the thermal shock and dilatation-contraction events, resulting in blistering and deformation of the top coat.