As part of this study, a comprehensive analysis of metrological approaches to detecting defects in thermal insulation of buildings using infrared thermography methods was conducted. It is noted that the assessment of heat losses and thermographic flaw detection of thermal insulation are important tools for reducing operating costs, improving working conditions and increasing the competitiveness of construction companies. It is indicated that the optimal format for presenting a thermogram should ensure the preservation of spatial and temperature resolution, correct artifacts and adapt data for statistical processing, which increases the accuracy of diagnostics. For a more accurate analysis, the concepts of current temperature contrast and differentiated contrast were introduced, which significantly increases the signal-to-noise ratio and allows determining the depth of defects, improving the accuracy of thermographic examination. The results of thermographic flaw detection are evaluated by comparing the temperature probability distributions for areas without defects and with defects, which allows determining the accuracy using the signal-to-noise ratio. The proposed method also includes taking into account neighboring elements to increase accuracy, and the analysis of time and frequency parameters of thermograms allows creating a multi-level defect map, which allows for a more detailed assessment of the condition of the object.