A constant limitation of a general home inspection is that the inspector’s method is always non-invasive and non-destructive. If there is a defect in a wall, but no visual evidence of its existence…there is no way an inspector will know. There must be some evidence. Conducting a thermal infrared inspection with a thermal camera helps to bridge that gap, and while a thermal camera has its limitations (It cannot see through walls!), it can provide some extra clues for the inspector that may lead to additional discoveries.
To illustrate an inspector’s typical limitations, and how a thermal camera can help enhance the quality of their inspection, I’ll be sharing a set of defects that I was able to document due to the use of my thermal camera.
These thermal defects were quite unmistakable, but simple finds can be the most rewarding. There were two defects that I found during this inspection. I’ll provide six photos, three for each mistake.
Locating a Hidden Supply Air Duct With a Thermal Camera
I was conducting a thermal scan around the interior of a home when I found a surface temperature anomaly with my imager. Now, on this day it was cold outside, so I had both of the home’s furnaces in the heating mode (This was done to establish a temperature differential between the indoor and outdoor environments.)
Because the furnace was in operation, the heat from the duct created a sizeable red splotch on the wall. Instantly I knew what I had detected; the sheetrock crew had neglected to cut out the hole for the supply air vent in the wall.
In this case, without the imager, I would have never known. The second image shows how the wall looked to everyone else…perfectly fine! I included the third image to display the repair that was implemented as a result of my finding.
Locating a Hidden Recessed Light With a Thermal Camera
The second defect was found near the first but on the upper ceiling. In this case, the sheetrock crew covered up a recessed light for the stairway. The fixture did not have a bulb in it, but since it was cold in the attic, the metal in the fixture pressed against the sheetrock which allowed me to see it with my camera. You may be interested in the blue lines in the thermal image; those are the 2×6 ceiling joists, and the dots are the sheetrock fasteners.
Based on the shape and location of the temperature anomaly, I was able to correctly deduce that I had found a covered light fixture.
These two defects are just examples of why I always perform a thermal scan with each one of my inspections at no additional cost to my clients. Even without a well-defined temperature split between the indoor and outdoor environments, I would have found that abandoned supply air duct.
Over time that duct would have created a mold and mildew issue for my client, as blowing cold air on the back of an attic wall will generate plenty of condensation.