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We were recently contacted by a prominent commercial roofing company based in the Dallas/Fort Worth area to conduct a thermal drone inspection of a large condo complex. The building had a modified roof that was covered with spray foam.

We initiated the process just like we always do — checking local weather to find the optimal day for the job, ensuring our equipment was ready to go, and obtaining authorization to fly in the controlled airspace surrounding the building. Then, we were ready to begin.

Performing a Thermal Inspection on an SPF Roof

SPF roofs are somewhat uncommon when it comes to commercial roofing. When it comes to performing an aerial thermal inspection on this type of roof, there are some unique challenges and considerations.

For instance, in these cases, spray foam is basically used to cover the old roof structure. That being the case, it is possible that existing moisture could be trapped underneath the spray foam.

But depending on the thickness of the spray foam application, the transmissive characteristics of the material could pose a problem. In other words, the infrared radiation (heat signature) coming off any moisture trapped underneath the underlying roof surface might be hindered by the insulative properties of the spray foam.

Thus, it can theoretically be difficult to detect this moisture on in infrared scan. However, any moisture that has penetrated the newer spray foam and is trapped between the foam and the underlying roof structure should be evident on the scan provided the environmental conditions are right.

As is the case with any thermal roof inspection, to ensure optimal results, the scan should take place at least an hour after sunset following a bright and sunny day. Temperatures in the area were in the high 90s for several days preceding the scan, which is important for two reasons.

First, this ensures that any surface moisture would have evaporated and would not cause a “false positive” so to speak during the thermal scan. In other words, the presence of surface moisture can provide inaccurate results, as it will be largely indistinguishable from moisture ingress in a thermal image.

And second, the warmer temperatures ensure that any moisture present in the first several inches of roofing material will have plenty of infrared radiation to emit during the thermal inspection; the hotter and sunnier it is during the day, the greater the potential for a clear temperature variation at night during the thermal scan, which is exactly what we are looking for.

Curious about how to interpret thermal images? Check out our guide.

The Results

So, what were the results of the inspection? Ultimately, we ended up positively identifying a few areas of potential moisture intrusion. This roof had a designated walkway of sorts that had been lined with floor mats, presumably for maintenance personnel to have a path to follow between vents, HVAC units, and other structures on the roof.

We noticed a fair number of thermal anomalies present along this general area. It is reasonable to conclude that this area is likely a low point on the roof, and over time, moisture made its way past the spray foam and settled in this area. You can take a look below.

As you can see, there is a noticeable line/string of “hot spots” running nearly congruent with the path of floor mats.

Based on where these areas are located (along a walkway that has likely been utilized countless times over the last couple decades) and the thermal anomalies observed, we were able to direct the roofing company toward this general area for further investigation and emphasis when it comes to the bidding and restoration process.

Be sure to read more about our thermal drone roof inspection services.