In low sloped roofing systems using porous insulation, the presence of water can significantly degrade thermal performance. Because of the different thermal characteristics of wet and dry insulation, there is often a surface temperature differential between areas of wet and dry insulation. Under the right circumstances, the areas of wet insulation can be detected by means of infrared sensing techniques. To better define the conditions under which infrared techniques can distinguish between areas of wet and dry insulation, a mathematical model was developed. This model is a one-dimensional, transient heat transfer model of a roofing system. The model considers conduction through the roof, insolation, radiant exchange between roof and sky, convective heat transfer between the roof and air, and the influence of moisture trapped in insulation. For one particular roof system, a parametric study was undertaken using this model to determine the influence of moisture content, outside air temperature, wind speed, insolation, sky temperature, and other factors on the roof surface temperature. Preliminary recommendations for employing thermal sensing techniques to locate wet insulation are developed.