Durability of ETICS and Premixed One-Coat Renders in Natural Exposure Conditions


In situ testing is a precious auxiliary mean to reduce the subjectivity of visual inspections, leading to a more accurate characterization of existing degradation mechanisms of buildings systems. Inspections under natural conditions over time can increase the knowledge of in-service behaviour and can contribute also to a better correlation between accelerated and natural ageing tests. The knowledge of performance during time of façades’ cladding allows maintenance planning and adequate interventions during the life cycle of these systems. This work presents data collected from field experimental campaigns carried out over 10 years after construction using several premixed one-coat rendered walls and during 4 and 6 years after construction in the case of External Thermal Insulation Composite Systems (ETICS), in order to study the water resistance of cladding systems under real service conditions. This analysis was focused on the study of the influence of the hydrophobic agent (salts of fatty acids and waxes or silanes for organic renders in ETICS) on the performance in terms of surface condition and water penetration. In addition, adhesion results, concerning premixed one-coat render, were also collected. The quantitative results obtained were correlated with visual inspection data in order to define potential relationships between common anomalies in such façade solutions and the main causes. This information will contribute to the development of solutions to prevent early ageing and adequate maintenance methodologies to delay their effect. Indeed, the results obtained showed that rendering solutions ageing, especially after 5 or 6 years in service, is a consequence of their loss in resistance to liquid water absorption, especially at the surface. Considering the ageing and water penetration processes are stronger for South and West orientations, additional mechanisms such as leaching of hydrophobic agents from the mortars and photochemical degradation are thought to be involved. Finally, the Karsten pipe testing proved to be the most reliable methodology to determine the loss of water penetration resistance of render solutions and predict the ageing of façade solutions.


Luís Silva , Inês Flores-Colen, Nuno Vieira, Ana Barros Timmons, Pedro Sequeira

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