Flat Roof Inspections - Core Sample

For those with experience with commercial flat roof IR inspections. Are you doing the core sample to verify moisture, or is the verification left to the end user, and their desired contractor?


If you plan to do core sampling on a roof, you better be hooked up with a reputable roofer to repair the core hole. And what if there is no moisture problem, now you got a patched roof.
Better let the condition of a roof left to the client and roofer of his choice after it has been inspected by aa qualified roofer. JMO

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I’m not looking to do the core sampling, if I don’t need to. I’m just looking to better understand the process, and who is involved, and the role the thermographer has.

When looking at a flat roof you should endeavor to views the steel/wood deck from underneath paying particular attention for rust or moisture tracing. You may need to lift a suspended ceiling or look into the cavity through access points. Some phenolic deck insulation under the roof covering can produce a toxic, acidic leachate that can corrode steel decks through from the topside. Only fix is to replace the roof covering and topside insulation.

D’Arcy, when I did it I brought my own qualified roofer and recored and patched as was stated in my agreement.

He was really qualified:


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You can’t afford the insurance if you touch that roof with a tool…

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No. Why would you?
A good moisture meter with thermogram overlay will pin point areas of concern.
Curbs, Boxes, Seams, Expansion joints, Pitch-pots flashings.
All can be archived atop the roof covering assembly.

You do realize that moisture meters do not work on some types of roofing materials…

Pin meters damage the roof.
Others measure density, not moisture. There are all kinds of anomaly sources under flat roofs.

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I did not realize that. My Tramex MHRIII with 1.5 penetration depth or Tramex RWS Depth of penetration @ 4", atop areas of concern .
Only BUR, Modified, TPO in my neck of the woods.

Here is one resource of why core samples are needed at times. Certainly not something that should be attempted during the normal course of a visual inspection.

The Many Purposes of Taking Core Samples in Roofing | Destructive Test | Roof Layers | Benchmark Inc..

I concur but that was not the OP’s question.
For those with experience with commercial flat roof IR inspections. Are you doing the core sample to verify moisture, or is the verification left to the end user, and their desired contractor?

Not required. You should be able to verify moisture.

Roof inspection for moisture is done to a different standard and process.
We provide the locations for further testing to be performed by the client.
There is little to no reason to use a moisture meter for verification. If you follow the process, IR is as good as it gets for non-distruction testing. A moisture meter will give you so many false positives it will drive you crazy! It will also only tell you if a leak is currently wet.

Most of my work these days is diagnostics of drone scans. I can’t do a moisture test from 400’ for one, but a qualitative approach will identify what is and is not moisture. It will determine if it is water damage even if it’s dry (today). Some leaks are seasonal.

One of the most surprising things I came across, it that it is very possible to scan creek gravel ballast roofs. Something that is said can not be done without removal. The right equipment and procedure is required, but it goes against “the book”. “Verify all potential moisture with a moisture meter” has been long time removed from my playbook. I actually presented the process at a clinic for a Flir convention on the subject.

I have discussed this often in the past here that neither IR nor moisture meters measure moisture. I feel that many students feel the moisture meter used to verify IR means it is more reliable, when it is not. It does at times increase your chances in identifying moisture, but at the same time will produce false positives from conflict between devices.

Think of it this way. When doing roof scans, we are looking for warm exceptions under the roof. A moisture meter (pinless) detects density. Density of a dry material holds more heat than other parts of the roof, longer. So your seeing what you think your looking for, a warm spot in the roof. What IR can provide is an apparent temperature that will help identify the difference between the two. You have to know what your looking for, and what it is going to register in the camera as. Does the anomaly fall in the temperature range of moisture?

Just need to figure which light colors/temperatures are water, water damage, insulation damage, moisture on top of the roof, BUR gravel blown into a pile… They are all in this one.


The guy really took care of your roofing job per your agreement.