While many infrared applications have been developed over the years, infrared roof moisture surveying remains one of the most difficult for thermographers to understand. This is due in large part to the fact that there are so many different roofs; roofs types, roof waterproofing, roof insulations, roof substrates, and roof decks. The thermographer must understand the thermodynamic characteristics for each individual type of roof and each combination in the substrate, which can be vastly different depending on many factors such as weather over the past 48 hours, solar insolation during the preceding day, ambient conditions at the time of the survey and what is going on thermally under the building roof. While infrared thermography is the best practice condition monitoring predictive maintenance technique for roofs, it is often performed incorrectly.

There are many different types of roof systems, but there is one common primary purpose of a roof; to keep water out of the inside of the building. Water that makes its way inside the building can also be found using infrared thermography, but this paper focuses on finding entrained moisture within the roof system of flat and low-sloped roofing systems.