Infrared cameras detect energy waves that are radiated or reflected from building materials in the infrared wavelength. This is a longer wavelength of energy than the human eye is capable of seeing. An infrared camera records these energy waves and converts them to tempertures, which are then converted to a colored picture for interpretation.
Due to the evaporative cooling of wet materials, small differences in temperature of affected building materials will show up on the camera screen. Also, the differing thermal conductance coefficients of different building materials that make up a wall or ceiling assembly will enable the camera to "see" defects or missing insulation "inside the wall." For commercial roof leaks or EIFS system leaks, the IR camera technology takes advantage of the high thermal capacitance of water compared to building materials, to detect water intrusion.
Infrared Thermography enables the user to scan the whole room/area in a fraction of the time it used to take.