This book focuses on the development of methods and systems for non-destructive testing and technical diagnostics of the thermal properties of construction materials and products. It presents physical and mathematical models of temperature fields within the studied objects under both contact and non-contact thermal influences—whether from linear, disk-shaped, or point heat sources—that accurately describe heat transfer processes in the examined items. The book also offers a mathematical framework for understanding the organized thermal regimes on the surfaces of samples subjected to symmetrical heating or cooling. Additionally, it provides an analysis of measurement errors associated with the developed methods and the measurement systems that implement them. This work will be valuable for scientific and engineering professionals, university educators, graduate students, and undergraduates involved in research and technical diagnostics.