Moisture in a building structure can originate from several different sources, e.g.:

• External leaks, such as floods, leaking fire hydrants etc.
• Internal leaks, such as freshwater piping, waste water piping etc.
• Condensation, which is humidity in the air falling out as liquid water due to condensation on cold surfaces.
• Building moisture, which is any moisture in the building material prior to erecting the building structure.
• Water remaining from firefighting.

As a non-destructive detection method, using an infrared camera has a number of advantages over other methods, and a few disadvantages.

Advantages

• The method is quick
• The method is a non-intrusive means of investigation
• The method does not require relocation of the occupants
• The method features an illustrative visual presentation of findings
• The method confirms failure points and moisture migration paths.

Disadvantages

• The method only detects surface temperature differentials and can not see through walls
• The method can not detect subsurface damage.
• Without getting too technical the basics of these cameras is simply that through infrared the camera measures the temperature of the surface it is pointed at-displaying very sensitive variations. In order to detect damp timber and other wall/roof members, the camera will differentiate between the temperature of the wall lining and the temperature of the stud. The mass of the stud will provide a slightly different wall surface temperature. If the stud is wet there will be further temperature variance. These varying temperatures are converted to an image and displayed on a LCD screen.