Thermal imaging uses technology that detects differentials in heat energy. A Thermal camera creates an image based on thermal energy rather than visible light. It is particularly useful in brick veneer constructions. When termites have concentrations of activity or nesting within walls, the thermal camera can detect the heat caused by that activity. Many things can cause heat in houses so when heat is detected it does not necessarily mean that termites are present. Minor amounts of termite activity will not cause the differentials in heat required for termites to be detected. Often thermal imaging will reveal inactive termite nests and damage because the abandoned mudding within the brick veneer will appear cooler than the surrounding wall. Because thermal imaging is non-destructive and often reveals concealed termite activity, we use it on Prior to Purchase inspections reports.

Thermal imaging creates an image of an object in the camera viewfinder from the thermal energy it receives. Just as sound exists beyond the human ability to hear, light contains wavelengths that are beyond the human ability to see. One example is thermal energy, which we feel as heat.

When heat permeates through a stud wall it is slowed down at the point where the timber frame inside touches the internal wall lining, allowing us to see an impression of the frame inside. Irregularities in this frame can indicate termite mudding, and a missing section may be an indicator of termite damage. As less heat is transferring through internal walls of a house than perimeter external walls, detection to the internal walls is limited.

Active termites maintain their galleries at a nice warm temperature. When there are concentrations of termite activity they can even change the surface temperature of the wall lining enough for the thermal camera to see it as a warm spot. However, if the ambient temperature of the wall is the same as the termite workings, the termite activity will not be detected, and it is therefore not recommended for thermal imaging to be carried out when the ambient temperature is greater than 23 degrees Celsius.

If the infestation is not concentrated enough to alter the surface temperature of the wall lining being scanned, the area will not appear hotter in the thermal camera.

If the infestation is not active at the time of the inspection, or areas of the infestation are not active, then little may be detected with the thermal camera. The very nature of termite activity means that they do come and go with changing conditions on the site.

Many other things in the house will cause heat; electrical circuits, hot water pipes, refrigerators, and hot water systems all cause heat. For this reason, when heat is detected we must first attempt to find the cause, and determine whether termite activity is also a factor, using moisture meters and movement detectors. For example, it is common for termites to use the heat from refrigeration units and concentrate their activities around it. It is not good enough to find heat and pass it off simply as heat from the refrigerator, as termites could also be present.

Used properly in conjunction with other tools, and most importantly with a thorough visual inspection, we are able to detect far more using thermal imaging than can be found by visual inspection alone, however the following pre inspection preparation will dramatically enhance what can be detected.

  • Remove other heat sources from the house - dogs, cats and other pets will cause heat deviations.

  • Turn off any unnecessary appliances - even a personal computer running will cause a heat deviation in a nearby wall. Appliances in standby also create heat deviations.

  • Turn off any air conditioners or heaters. We want a stable ambient temperature in the building.

  • Make access to all the walls - (as full and free as possible) the more of the walls we can see the more we can detect.

  • Provide any previous inspection reports carried out on the house or any history of previous treatments, or previous termite activity, where possible.

  • Ensure access to the property is arranged for a part of the day that is not too hot. During summer the morning is best, however in cooler weather termites may not be active early in the morning, so the afternoon may be better.