| Summary: | Ceramic detachment is a serious problem that persists in modern building constructions despite technological advances and updated regulatory documents. Most of these detachments occur at the interface between the adhesive mortar and the ceramic tile, due to the action of simultaneous tensile and shearing efforts. However, despite this understanding, experimental studies that evaluate the integrity of the adhesion of façades covering materials subjected to simultaneous stress are scarce. In this sense, this study proposes to evaluate the integrity of adhesive mortar joints using the mixed-mode flexure (MMF) crack propagation test. Force and elastic and dissipated energy data were used in this analysis. Prismatic specimens, with a size of 160 × 40 mm<sup>2</sup> and a thickness of 6 mm, were produced consisting of two ceramic plates joined by a layer of adhesive mortar at 5 ± 0.5 mm. An acetate film was inserted into one of the mortar–ceramic interfaces in order to simulate the presence of a previous crack, and different crack sizes were used. The results showed the high stress-concentrating effect that the existence of flaws in the interface region has on fracture resistance, as well as the importance of effective contact between the materials. The energy parameters confirmed the analyses carried out based on the load values. The elastic energy of the system fell in the cracked samples, showing that there is a close relationship between the interface energy and the adhesive strength of the material. An energy release of the order of 0.053 ± 0.031 J was required for a 15 mm crack to propagate, creating a fracture surface.
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