Thermal renders applied in multilayer systems are a recent trend in the building
industry, besides ETICS. This type of systems aims at lowering the envelope U-Value with
an upgraded thermal resistance of its components. As building rehabilitation has been
increasing on a large scale, these solutions are of major interest, due to its easier
application (by mechanical spraying) and enhanced hygrothermal properties. Durability
assessment is a crucial issue to systematize and improve the knowledge of wall multilayer
systems. Optimizing their application must take into account the actual climatic
conditions. However, durability assessment procedures applied specifically to thermal
render systems do not exist. The main goal of the present paper is to cover the gap in
terms of durability assessment of thermal render systems defining a methodology based on
accelerated ageing, taking into account the render matrix, hygrothermal and mechanical
properties and also climate action. The first part of the work focus the analysis of
durability assessment of existing standards, which are applied to renders and multilayer
systems (EN 998-1, EN 1015 and ETAG 004). Also, some authors have worked on the
calculation of acceleration factors and definition of new accelerated ageing protocols, by
analysing the results of natural ageing tests and climate data. In a second part,
hygrothermal simulations, using the WUFI Pro software, are performed to evaluate the
thermal render systems performance, in different climates. The results were analysed to
support and complement the previous knowledge and lead to the definition of a durability
assessment methodology applied to thermal render systems
