The Myth of Infrared, Continued

Now, moving to the next level of complication, we’ll introduce the fifty-cent word “emissivity.” Emissivity explains that all surfaces, being made up of different materials, emit or reflect infrared energy differently. That means if you look at human skin, drywall or metal that are all at the same temperature, in infrared they’ll register much differently. On a clear hot summer day, the imager may show a puddle of water on a flat roof as being -20° F, and it’s not malfunctioning.
So now we come to the next step, interpreting, which is routinely the most complicated and the most susceptible to error. On occasion, especially if you know what you’re looking for, images can be interpreted on the spot. However, in true thermography, the pictures will be downloaded to a computer via proprietary software for interpretation. Last in the process is confirming the findings by destructive investigation (taking things apart) which is, again, beyond the scope of a home inspection.
In the world of building science these imagers have been commercially used since the 1980s and have become an integral part of inspecting commercial electrical and flat roof systems. As their usage grew, organizations such as the ASNT (American Society for Nondestructive Testing) and ISO (International Standards Organization) established standards for imagers and operators. What the operator is looking for dictates which standard is to be used. Think of a standard as a recipe for baking a cake; if you don’t follow the recipe closely, the cake probably won’t turn out very well. Need I say much more than there is no standard for thermography as part of a home inspection. Also, although prices continue to drop, current imagers meeting the basic standards for commercial use start around $5,000, which is more than the cost of most home inspectors’ entire tool box.
Now let’s talk about operating the imager. Although they come with a manual and software, we’re no longer in the world of point-and-shoot or plug-and-play. These are a scientific tool that, if misused, can get an operator into a lot of trouble. The following is a sample of the designations currently in use.
Thermography (A Basic Overview)
  • Level I: Training typically costs $1,600 to $2,000 and involves 30 hours of in-class training. This provides the operator with the skill required to take images along with a basic understanding of interpreting them. Notice that I am stressing interpreting.


  • Level II: Training typically costs $1,600 to $2,000 and involves 30 hours in-class with a prerequisite for over 1,000 hours of imager use, and focuses mainly on interpreting images.


  • Level III: Involves the same time and financial commitment and delves more into the science of thermography and trains one to teach thermography and lead a thermography team.