Shielding building' facades on cities revitalization. Triple-resistance for water, graffiti and biocolonization of external thermal insulation systems.

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Effects of hygrothermal, UV and SO2 accelerated ageing on the durability of ETICS in urban environments

Publication . Parracha, João L.; Borsoi, Giovanni; Veiga, Rosário; Flores-Colen, Inês; Nunes, Lina; Garcia, Ana; Ilharco, Laura M.; Dionísio, Amélia; Faria, Paulina

External Thermal Insulation Composite Systems (ETICS) have been extensively used for either new constructions or building facades retrofitting in the last decades. These systems can provide improved thermal performance to the building envelope. However, their long-term durability remains a pervasive concern, with some systems presenting relevant anomalies after few years from their application. The durability assessment of ETICS is defined by the EAD 040083-00-0404 guideline, which stated an accelerated ageing procedure based on the hygrothermal and freeze-thaw behaviour. Nevertheless, further important environmental urban conditions, such as UV radiation and atmospheric pollutants, as well as bio-susceptibility, are not envisaged in the guideline. This paper presents the results of an experimental campaign with the aim of evaluating the durability of the rendering system of several commercially available ETICS exposed to an innovative accelerated ageing procedure, which consists of hygrothermal cycles, UV radiation and air pollutants (SO2) exposure. Physical and chemicalmorphological tests were carried out prior and after each ageing cycle in order to evaluate the durability of ETICS. Biological susceptibility to moulds was also assessed. The experimental results showed that both surface hardness and surface gloss decreased after the combined effect of the hygrothermal, UV, and SO2 ageing cycles, whereas an increase of surface roughness was observed. Substantial colour change for all systems after the ageing procedure was observed, confirming aesthetic alteration. Traces of biological growth were detected on the systems after ageing and the contact angle decreased after the hygrothermal cycles, indicating a lower surface hydrophobicity of the systems.

2021Journal article

Restricted access

Long-term performance of thermal insulating composite systems based on water resistance and surface multifunctionality

Publication . Borsoi, Giovanni; Parracha, João L.; Bersch, Jéssica D.; Garcia, Ana; Dionísio, Amélia; Faria, Paulina; Veiga, Rosário; Flores-Colen, Inês

External Thermal Insulation Composite Systems (ETICSs) are increasingly applied in both new construction and energy retrofitting, where long-term durability under environmental exposure is critical to preserving thermal efficiency. Moisture ingress represents a key degradation factor, reducing insulation performance and undermining energy savings promoted by the ETICS. The effectiveness of these systems is strongly influenced by surface protection, which also reflects aesthetic and biological resistance. This study investigates the influence of three commercial protective surface coatings, characterized by hydrophobicity, photocatalytic activity, and resistance to biological growth, on ETICS finishes based on acrylic, natural hydraulic lime (NHL), and silicate binders. An artificial aging protocol was employed to evaluate coating stability and compatibility with the finishing layers. Results show that acrylic-based finishes provided superior durability and protection, while coatings on NHL and silicate substrates exhibited lower performance. Notably, a TiO2 enriched photocatalytic coating, despite improved self-cleaning potential, demonstrated the least durability. The findings highlight that optimal ETICS protection requires coatings that combine low water absorption, effective drying, and biological resistance, thereby ensuring sustained thermal and energy performance over time.

2025-09-20Journal article

Open access