The mechanical characterisation of existing brick masonry structures requires a strategic selection of testing methods to balance material preservation with the need for comprehensive data acquisition. Various tests provide different insights into structural properties while inducing varying levels of material damage. A combination of Non Destructive Testing (NDT) and Minor Destructive Testing (MDT) is essential for a detailed and accurate assessment. This study proposes a methodology for assessing existing heritage masonry structures through in situ quantitative evaluation. The approach integrates the Rebound Hammer (RH) and Ultrasonic Pulse Velocity (UPV) tests to analyse bricks. In addition to provide quantitative measures, these techniques can be used for a qualitative sampling and comparison over different areas within a single structure, allowing a better understanding of the scattering of the mechanical properties. By utilising empirical correlation curves, the combination of RH and UPV, referred to as the SonReb method, enables an approximate quantitative evaluation of the brick mechanical properties. Additionally, the Pin Penetration Test (PPT) is employed to evaluate mortar strength. The proposed methodology is applied to multiple case studies, demonstrating its effectiveness in evaluating masonry structures. The combination of these testing methods provides a more thorough understanding of material properties while minimising structural damage, making it particularly suitable for heritage conservation projects.