Dark Spots on Ceiling using Infrared

Hey everyone. Hope your all doing well.

I am starting to train and use the infrared camera so that I can start offering this service to clients. I have taken some training and will do more but in the meantime, wondering if anyone can give some advice as I want to learn.

Attached are some photos from a bedroom (my own house) and noticed that in both bedrooms at the ceiling of the exterior wall, there are these dark spots. I didn’t notice anything in the attic but was not able to walk all the way inside.

My moisture meter did not pick up any readings. My thinking is that those dark spots are air leaks which is creating cool air all along the top. I was thinking missing insulation but it looks
too much like a pattern of spots. Just curious.



Thermal bridging on the cripple posts or joists?

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Gotta be something with the joists right? Because they’re spaced like joists. Maybe the tail end that’s exposed to the cold outside conducts that outdoor cold air but the rest of the joist is in much warmer conditions and insulated which is why you don’t see it transferring up it. You can also see that header as well, looks very cold there!

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Yea, that makes sense, Thanks Shane. That’s where my thought process was going but not as thorough like you mentioned.

Stay Safe and Be Well.


I thought about the cripples too but you can see the rim joist in the corner perfectly spaced with the rest of them so it has to be joists.

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No, it is not conductive. It is convective. The insulation is not fitted well at the end and allows air leakage.

No, it is not an issue at all.

As for your 2nd scan; just so you know, that spot temperature is incorrect. You have a low end camera. Thus the large spot measurement size. If everything inside the spot is not the same color, you need to get closer. All the temps inside that circle is being averaged and gives the wrong reading.

FoRD: Focus Range and Distance are critical before you record the scan. Distance is wrong.

If your camera has an Area Measurement Tool and has highest/lowest temp indicators inside the box, use that if you just can’t get any closer,


Thanks David, appreciate the feedback.

Reflect upon insulation. The anomaly is cooler, even the anomaly pattern, and pallet blush hue, does not spread out in softer blushes.

If this would be moisture intrusion, I suspect there would likely be optical signs on the drywall or tape joints you could see with the naked eye. Blisters, peeling, bumpiness, the paint hue darker.

Be it any type of insulation, the blanket should be: A: Even in density and thickness throughout the stud or joists bay. B: Completely fill a stud or joist bay leaving no gaps or voids on all side. Even compressed areas of glass fiber batting leaves cooler patterns. Uneven spray foam leaves cooler wavy patterns.

Many times insulation installers are general laborers that rush the job to completion, especially in areas hard to reach like upper corners on a wall assembly.
Be it any type of insulation, the corners have the most anomalies I find. They fail to ‘tuck the glass fiber batting into corners evenly.’

Just my 2 cents.

Morning, David.
Hope this post finds you well.

Likely the equipment the OP is using can not compensate for distance or adjust level and span.

Morning, Max.

Could you indicate to the remembers what infrared camera model you were using to take the thermogram images please. As well, what settings you set the camera to prior taking the thermograms.
Looking forward to your reply.

Good morning Robert.

Hope all is well with you and your not getting too much snow :grinning:

Appreciate your feedback. Its always great to learn from your experience. I was using the Flir C5 camera.

Best Regards

In this case (for the OP), these gaps do not have to be significant. You looked in the attic and didn’t find anything. You won’t see the cause of these air leaks in many cases w/o your imager. That is what thermography is all about.

What you have shown us here is totally normal installation and building construction. Heat moves through the structure from hot to cold at different rates. This is what your seeing.

There will always be this type of thing going on at the exterior wall/ceiling juncture. That is because there is insufficient space at the eve for insulation and you are required to share this space with attic ventilation requirements.

There are three methods of heat transfer; Conduction, Convection and Radiation. It is possible that all three are going on at the same time. You must understand how much of each one is occurring each time you take a scan because they must all equal 100%.
In your case someone called Conductance and I called it Convection. Both of us are correct, but your asking about the dark spots. Conductance is always happening in a building but convection is responsible for the highest % of heat transfer causing your dark spots.


This is for the OP based on Roberts post of which I concur:

Yes there are some really crap cameras that have fixed settings; and this camera qualifies

C5: 160x120 resolution
Digital Camera Focus: Fixed
Level/Span: Automatic
Thermal Sensitivity/NETD: At ambient temperature 59 to 95°F (15 to 35°C) and object temperature above 32°F (0°C)
32 to 212°F (0 to 100°C): ±5.5°F (±3°C)
Thermal Sensitivity/NETD: <70 mK
This all really sucks.

Distance is about the distance from the camera to the target (for the OP).

The primary concern is about atmospheric attenuation, but if you get too far away your camera will not record a small object if it falls below the spacial resolution capacity of the camera.

The only way a camera can compensate for distance is by changing the camera lens. Can’t do that here.

If you are recording a spot temperature, you must move as close to the target as you can and never have different colors in the spot measurement area. All cameras consider Multiple pixel data to come up with a measurement by averaging them. Crap cameras require bigger measurement tools because they require more pixels to average and the spacial resolution (space between the pixels) are further apart. This is where resolution/sensitivity comes in. All 160x120 cameras are not created equal.

These adjustments should always be performed before we put anything into a report, generally done on the computer. There are always things hidden in a scan that is not properly tuned. So in your camera auto tune your potential to miss stuff in plain sight is huge. There may be several targets in one scan, so that scan must be tuned for each target in that scan.

Hope you keep these facts in mind as you continue your thermal education. As Clint said, “A man must know his limitations”.

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Here is a thermogram looking into the eave.

Thanks David. I appreciate all the feedback. I am taking all this and will apply it and of course continue my education on thermal imaging.

Have a great weekend

Insulation, or lack there of, between stud bays. The coldest spot is from a gasket less exterior receptacle on the outer wall. Air infiltrates’ the inner wall assembly.

This… very little insulation toward the eaves and the outside cold is transmitted easily by the metal