One main reason that building materials degrade is because they are affected by water. It is fundamental to the preservation and maintenance of all buildings that they remain as watertight as their design will allow.
Moisture damage is the most common form of deterioration in a building. Air leakage can cause condensation to form within walls, floors, or ceilings. Wet insulation takes a long time to dry and becomes a prime location for mould and fungi.
Scanning with a thermal imaging camera can locate moisture that creates an environment conducive to mould growth. One might smell its presence, but not know where it is forming. A thermal survey will determine where moist areas are located that can lead to serious mould which can lead to health issues.
Moisture intrusion in a floor, impossible to see with the human eye, but is clearly visible on the thermal image.