IR for Detection of Exterior Wall Moisture and Delamination: A Case Study and Comparison to FEA Predictions

Surface thermal anomalies will be caused by structural and moisture conditions. In warm season conditions, the exterior wall can be expected to be warmer than the interior. The following discussion is based on that scenario. Over a daily cycle of solar heating and air temperature-driven heating during the day and convective and radiational cooling at night, the surface of the facade will respond in a manner indicative of and caused by its condition and underlying materials. During solar exposure, starting from a cool nighttime state, areas that are thermally better connected to the interior, that is, not well insulated, will warm more slowly. Similarly, those areas with higher thermal mass, such as trapped water, will also warm more slowly. Areas that are not well connected, such as those over disbonds or delaminations, will be unable to dissipate the applied heat as readily and will warm more quickly and to a greater degree than the "normal" areas. The reverse behavior will be observed during a cooling phase: wet areas or areas that draw more readily from the interior will stay warmer, and disbonded areas will cool more rapidly.