27.2.1.2 Guidelines for moisture detection, mold detection & detection of
water damages
■ Building defects related to moisture and water damages may only show up when
heat has been applied to the surface, e.g. from the sun.
■ The presence of water changes the thermal conductivity and the thermal mass of
the building material. It may also change the surface temperature of building mate-
rial due to evaporative cooling. Thermal conductivity is a material’s ability to conduct
heat, while thermal mass is its ability to store heat.
■ Infrared inspection does not directly detect the presence of mold, rather it may be
used to find moisture where mold may develop or has already developed. Mold
requires temperatures between +4°C to +38°C (+40°F to +100°F), nutrients and
moisture to grow. Humidity levels above 50% can provide sufficient moisture to
enable mold to grow.
10556003;a1
Figure 27.2 Microscopic view of mold spore
27.2.1.3 Guidelines for detection of air infiltration & insulation deficiencies
■ For very accurate camera measurements, take measurements of the temperature
and enter this value in the camera.
■ It is recommended that there is a difference in pressure between the outside and
the inside of the building structure. This facilitates the analysis of the infrared images
and reveals deficiencies that would not be visible otherwise. Although a negative
pressure of between 10 and 50 Pa is recommended, carrying out the inspection
at a lower negative pressure may be acceptable. To do this, close all windows,
doors and ventilation ducts and then run the kitchen exhaust fan for some time to
reach a negative pressure of 5–10 Pa (applies to residential houses only).
134 Publ. No. 1558792 Rev. a460 – ENGLISH (EN) – July 1, 2010
27 – Introduction to building thermography
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