At Holloway Cook Associates we provide a Thermographic survey service. This is carried out using an Infrared camera which measures infrared radiation.
The survey is normally undertaken in the evening when the outside air temperature is starting to fall and the building starts to radiate out heat.
Wet insulation does not insulate, it loses heat which is then picked up by the camera. These areas show up as hot spots on the camera and they are then marked out on the roof area. These wet areas can then be replaced.