## 4 Conclusions  
This study assessed the effects of fire-induced thermal exposure on the hydric behavior of thirteen Portuguese carbonate stones and evaluated the ability of two non-destructive techniques, Leeb hardness (HL) and ultrasonic pulse velocity (UPV), to predict capillary water uptake under these altered conditions. Thermal damage was shown to significantly increase porosity and capillary absorption, especially above 300 \({}^{\circ}\)C. These changes result from microcrack propagation and anisotropic mineral expansion, which progressively compromise the stone's mechanical integrity. Among the techniques, UPV consistently demonstrated superior predictive capacity across lithologies and temperature ranges. Its volumetric sensitivity allowed it to capture internal degradation that directly influenced water transport. HL, while effective in dense and homogeneous stones like marble, showed limited performance in heterogeneous lithologies and at higher temperatures. Traverting, due to its anisotropic pore network, was excluded from the temperature-based regression analyses. While this highlights a limitation in the applicability of HL and UPV to highly heterogeneous stones, it also emphasizes the need to investigate complementary methods capable of more effectively resolving internal pore structures and water dynamics in such complex lithologies.  
Importantly, this research extends the application of HL and UPV beyond mechanical diagnostics, demonstrating their potential as non-invasive proxies for water transport behavior after fire events. These insights are especially pertinent in the context of increasing climate variability, where the frequency and intensity of extreme phenomena like wildfires are expected to rise. In this regard, the study contributes to a better understanding of how thermally induced damage can affect stone performance not only structurally, but also in terms of moisture regulation, a key factor in building conservation. In particular, UPV stands out as a practical field tool for post-fire diagnostics, especially in heritage contexts where invasive testing is restricted. Its volumetric sensitivity, portability, and ability to detect internal degradation without damaging the material make it especially valuable for rapid, in situ assessments. Ultimately, these findings support improved heritage risk evaluation and the deployment of efficient diagnostic strategies in conservation practice.  
Conceptualization, R.L., A.D. and G.P.; methodology, R.L.; validation, R.L., A.D. and G.P.; formal analysis, R.L., A.D. and G.P.; investigation, R.L.; data curation, R.L.; writing--original draft preparation, R.L., A.D. and G.P.; writing--review and editing, R.L., A.D. and G.P.; supervision, A.D. and G.P.; project administration, A.D. and G.P.; funding acquisition, A.D. and G.P. All authors have read and agreed to the published version of the manuscript.  
This research was funded by CERENA (FCT-UIDB/04028/2025 and FCT-UIDP/04028/2025), grant number UI/BD/152298/2021.  
Not applicable.  
Data Availability Statement: The raw data supporting the conclusions of this article will be made available by the authors on request.  
The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.