Evaluation method for hygrothermal performance of masonry rendering mortars: Assessing moisture and mould growth risk under brazilian climate conditions

Technological Research Institute of the State of São Paulo - Housing and Buildings/Laboratory of Materials for Construction Products, São Paulo, Brazil

^* Corresponding author: alexcord@ipt.br

Abstract

The presence of moisture in environments, when it exceeds certain limits and is associated with specific temperature ranges, can promote the growth of mould fungi inside buildings, compromising the health of occupants and leading to other harmful pathological manifestations affecting building performance. In this context, rendering mortars with paint application show significant potential to mitigate moisture ingress into building walls. This study aims to analyse normative trends related to criteria for water absorption by capillarity and resistance to vapour diffusion in masonry rendering mortars in Brazil. Additionally, we sought to identify gaps in existing standards and propose recommendations to enhance the suitability of rendering materials to the diverse climatic conditions found in the country. In this context, the results of the analysis of the hygrothermal behaviour of a wall rendering system are presented in this paper. The analysis, conducted through computational simulations, considered the climatic conditions of select Brazilian cities. Despite advancements in Brazilian standards, there are still gaps in existing norms regarding standardised criteria that allow for better selection of materials with performance compatible with their climatic context. The criteria outlined and the computational simulation method used were relevant in evaluating rendering materials under selected climatic conditions and have the potential to contribute to the development of more effective guidelines for the construction sector in Brazil.