One of the frequently used methods of stabilization and reinforcement of historic masonry is grouting, especially grouting of cracks and voids in masonry structures. Determination of the properties of the injected structure, both in terms of physico-mechanical properties (with regard to the subsequent compatibility of the grouting mixture) and in terms of its condition and failures (cracks, voids, cavities), is a prerequisite for correct design and realization of reinforcement grouting. Minimization of interventions into the historic structure while performing surveys and the associated use of non-destructive diagnostic methods is one of the requirements for the remediation of listed buildings. Within the experimental research of reinforcement of historic masonry structures, the possibility of using thermography and ultrasound methods was evaluated and conditions and limitations for the use of these non-destructive methods were formulated.