This chapter provides technical information and physics background to the use of thermographic cameras in the field of preservation and restoration of architectural cultural heritage. After an overview on how IR cameras work, both applications and common cases will be presented so that the operator may easily deal and recognize building pathologies and masonry anomalies. These, described in detail, range from water moist problems to structural gaps. As moisture and humidity related problems represent the majority of IR surveying cases in the field of architecture, they will be handled in a comprehensive way so that both the operator and the scholar are well prepared to understand and treat the pathologies these may cause. The operator is instructed on how to perform a project survey on a step by step layout based on the UNI 9252, the UNI EN 13187 and the ISO 9712:2005 regarding the methodologies of IR survey and the procedures of non destructive tests.