Thermal image example, Paul Probett, Incodo 2008 Thermography 101: Thermal Imaging in Building Surveys: Procedures, Errors, Warnings

  • THERMAL IMAGING, THERMOGRAPHY - CONTENTS: Thermal imaging equipment, procedures, advice & warnings: Advice on Using IR Infrared Scanning Equipment for Building Surveys. Applications for thermal imaging or IR scanners in building surveys. SOURCES of ERROR in Thermal Imaging and IR Temperature Measurements. KEY OBSERVSATION FACTORS in Moisture Detection (or heat loss detection) using Thermal Imaging. WHERE TO BUY IR Scanners, Cameras, & Thermography Equipment.THERMOGRAPHY CLASSES in use of thermographic equipment & thermal imaging & FLIR for building surveys
  • POST a QUESTION or READ FAQs about the use of Thermography & Thermal Imaging for Finding Building Leaks, Rot, Insect Damage, Heat Loss, Mold
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Guide to effective use of thermography: this article describes the use of thermography, infra red imagers or scanners for observing building component or temperature variations as a component of building inspection, testing or surveys as part of an energy audit, house doctoring, heat loss, moisture screening, or screening for hidden building damage or mold contamination.

We describe how thermal imaging is used in building surveys and we list sources of error in conclusions some may draw from examination of thermal images or data. We include sources of thermal imaging equipment, thermal scanners, and thermography education and training. Page top image of thermal scan results provided courtesy of Paul Probett, Incodo Ltd., a New Zealand Forensic Building Specialist.

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Thermography 101: Thermography & Thermal Images Used in Building Surveys

Paul Probett, Incodo Forensic Building Specialists [1]

This article is adapted with permission from Thermal Imaging and Building Surveying / Inspection, a 2008 presentation by Paul Probett. [2]

Article Contents

Thermal images and IR have been widely used with some success at spotting areas of heat loss in buildings and these tools have a longer history of use in examining overheated electrical connections, motors, etc.

Examples of Using IR Infrared Scanning Thermography Equipment for Building Surveys

We have made regular use of small hand-held IR or thermal scanner equipment in building inspection surveys for nearly twenty years. The two most common uses we've made of the equipment are described here.

Photograph of  this overheating and improperly-made aluminum to copper pigtail splice. Photograph of  this overheating and improperly-made aluminum to copper pigtail splice.

See ALUMINUM WIRING HAZARDS & REPAIRS for an example of aluminum wiring overheating shown in the two photographs at left.

  1. Building Heat Loss: Surveying buildings for variations in temperature, indicating areas of heat loss: air bypass leaks, missing insulation. In addition to spotting specific "cold spots", if there is a significant temperature difference between indoors and outside, thermography can quickly identify compare temperatures on interior partitions with exterior walls.
  2. Building Moisture Traps, Leaks: Surveying buildings for evidence of recent leaks, wet insulation in building cavities. Be careful: an old leak into a building cavity may have completely dried out, producing no IR detectable information, but problematic mold, rot, or insect damage could be present. Visual evidence of building leak history and a recording of building details likely to have led to leaks or water entry are important.
  3. Electrical overheating: a number of home inspectors have successfully used IR and thermography to identify overheating electrical components at electrical panels, electrical switches or receptacles, at wiring serving electric heating baseboards, and where aluminum branch circuit wiring is installed.

    Overheating electric motors, compressors, and even blower fan bearings can be observed using these methods as well, provided that you have a baseline of normal temperatures.
  4. Tracing heating elements such as the location of radiant heat tubing in floors or ceilings and finding leaks in those systems.

Are Thermal Images Useful in Spotting Areas of Extra Risk of Structural Rot Damage or Hidden Mold in Buildings?

Thermal image example, Paul Probett, Incodo 2008OPINION: DF: Thermal images and IR have been widely used with some success at spotting areas of heat loss in buildings and these tools have a longer history of use in examining overheated electrical connections, motors, etc. But for finding hidden mold, thermography is a risky proposition.

Image at left, courtesy Paul Probett, Incodo [1]

Watch out: in the hands of the un-trained or unscrupulous these and other tools can wreak havoc or harm to consumers.

The most egregious instrument snafu I've come across [DF] recently was a Hudson Valley New York "mold remediator" uses an IR camera to tell his clients where the hidden mold is located in their home - it was a modern version of the guy with the light meter who sold people replacement windows by showing clients where their heat loss was occurring - wherever there was light.

I did find areas of basement water entry and moldy insulation - in an area not addressed by the New York mold-thermographer. Details about using thermal imaging to look for hidden mold are


A different case - a thermal imaging report with almost no useful data, is discussed

Paul Probett adds: We had major problems with people buying thermal imagers, using ex military units and making ridiculous claims. In 2008 I gave a power-point presentation [25] to a conference explaining how IR results can be fudged and I described the limitations of thermal imagers.  (Our staff had been through the Infraspection Institute USA on-line course to level 2 the year before).

Mr. Probett's 2008 power point presentation on using thermography in building damage or mold surveys is adapted and expanded in the article text that follows.

Consumer Tip For Hiring a Building Surveyor or Mold Inspector

The person who screens your building for mold contamination or other possibly costly repairs and who defines the initial scope of work to be performed should have no business nor any other relationship with the contractor who will ultimately perform the work.

Reliance on "tests" for hidden mold without an expert visual inspection will not give the most reliable results and some building mold screening test methods are simply invalid.

See MOLD INFORMATION CENTER for extensive advice on building mold contamination.


See MOLD / ENVIRONMENTAL EXPERT, HIRE ? for help in determining if hiring an expert is probably justified.

Also see MOLD KILLING GUIDE for more typical mold-cleanup snafus.

Sources of Error in Thermal Imaging and IR Temperature Measurements

Thermal image example, Paul Probett, Incodo 2008Paul Probett, Incodo Forensic Building Specialists [1][2]

In our opinion, thermal imaging is a very useful tool for building surveys, but building inspection reports that rely primarily or only on thermal imaging tend to be flawed.

Images at left, courtesy Paul Probett, Incodo

Thermal image example, Paul Probett, Incodo 2008

Thermal image example, Paul Probett, Incodo 2008

Thermal image example, Paul Probett, Incodo 2008

Key Observation Factors in Moisture Detection (or heat loss detection) using Thermal Imaging

Thermal image example, Paul Probett, Incodo 2008


False positive thermal images are illustrated in Probett's slide shown at left.

At top right is the digital image of the building exterior wall.

At lower left is a thermal image that might be indicating a water leak or moisture collected inside the wall at its top section.

At lower right the image has been digitally manipulated to dramatize the apparent leak.


Thermal image example, Paul Probett, Incodo 2008


A thermal image can be manipulated by accident of how the image was collected (at an angle or with improper camera adjustments) or deliberately by an unscrupulous operator.

In these images Mr. Probett illustrates how easily a color image from a thermal imaging camera might be manipulated - in this case changing the color palette and contrast and temperature range to lose definition.



Thermal image example, Paul Probett, Incodo 2008


Examples of a false positive thermal image reading include the thermal images at left.





Thermal image example, Paul Probett, Incodo 2008


The thermal image shown at left illustrates wet or damp areas and concomitant temperature differences noted by the IR camera.

In this case the surveyor wasreporting on a gutter leak that sent water across the soffit and behind the fiber-cement cladding on the building wall.




Example Thermal Imaging Report

Thermal image example, Paul Probett, Incodo 2008The image at left illustrates a page from a typical thermal scan thermography report issued by Incodo.

[Click to enlarge this or any images in this article]





Data Recorded by Thermal Imaging Camera

Thermal image example, Paul Probett, Incodo 2008The thermal image at upper right in the Incodo slide illustrates important data recorded on FLIR thermal images:


Limitations of Thermal Imaging for Building Surveys

Thermal image example, Paul Probett, Incodo 2008


The thermal image at the upper right corner of Probett's slide illustrates a temperature difference that could point to a possible leak into a roof eave or soffit.

At lower left in the slide you can see a moisture meter reading being taken in the suspect area.



The Quality of Thermal Imaging Results Depends on Probett's 5 "Es"

Thermal imaging report of heat loss on a home (C) InspectApedia

  1. Expertise: (which is not the same as experience), including
    • Expertise in thermography generally, including some formal, internationally-recognized training
      ASTM type qualifications range from level 1 - 3

      Our thermal image of a building shown at left is an example of what in our OPINION was a worthless "thermal imaging report" provided by a reader and discussed

      [Click to enlarge any image]

    • Camera-specific training
    • Building-related expertise, building science, understanding how types of construction, construction details, construction materials, and other historic or visual clues predict hidden building problems
  2. Experience: this takes time and hands-on use of the camera, applying the training in 1. above.
  3. Equipment:

    The quality of the thermography or IR equipment used has a significant bearing on the quality of results that can be obtained. For moisture detection work, most authorities would suggest a sensitivity of at least 0.13K is required and preferably 0.10K or better
  4. Extra Equipment:

    By using other quality, non-destructive equipment such as moisture meters having a minimum penetration depth of 50mm there is an increased likelihood of actual moisture being detected and the number of false positives will be reduced. Mixing other NDT equipment such as capacitance, dielectric constant and microwave devices will increase the reliability of results
  5. Ethics:

    Some have a concern that there is a "cowboy" element operating in the thermal imaging / moisture detection industry. This is reflected in large variations in basic charge-out rates coupled with low-quality reports and outlandish claims as to equipment quality, cost, availability, etc. For example:

    "allows ... to effectively see right through walls of a house"
    "enables ... to pinpoint a problem when there is no other means available"
    "imaging for those who don't want often inaccurate cutting of holes" *

    *Quotes from New Zealand web pages, September 2007

    Reports can be prepared to give the owner what they want. For example, "proof" that their home doesn't leak.
  6. A Sixth "E" - Economics

    While not related to professional operations by a thermograph er., the charges relating to services offered vary widely and may not relate to any of the "Es" above. In fact in the U.S. Friedman reports [above] at least one mold remediation company who includes IR scans and thermographic work "free" as part of a building survey intended to sell his services.

Where to Buy IR Scanners, Cameras, Thermography Equipment
Where to FindThermography & FLIR Classes & Education

Thermal Scanner Attachments for Smartphones

FLIR ONE thermal imaging camera clip-on for iPhone (Android coming) - contact One™ is an iPhone™ attached thermal imaging camera (as well as a second imaging camera) that clips to the back of an iPhone™. One source gave a price of $350. U.S. vs. around $1000.+ U.S. for the FLIR "professional imagers".

According to the company, currently (2014) one has can purchase the FLIR ONE buy only in the U.S. though the company has offices and distributors world-wide.

The smartphone-attached thermal camera from FLIR thermal camera can detect temperature differences of about one-tenth of a Fahrenheit degree, and the temperature read-out is accurate to within 2°F.

The FLIR ONE™ iPhone-attached thermal imager is shown at left. An Android FLIR One™ model will be available later in 2014.

The image at left, adapted from FLIR One™ literature, shows the thermal imaging camera as a shell that snaps around an iPhone and takes its power from the phone's base connector. This thermal imager incorporates two camreas (thus those two small dark openings in the round silver disc on the imager's surface at upper right in our illustration): a thermal image lens (80x60 pixels) and a conventional imaging lens (640 x 480 pixels) allowing capture of conventional and thermal images of the same scene.

Other SmartPhone-connected Thermal Imaging Cameras and applications are available.

Therm-App thermal scanner camera smartphone attachment - adapted from http://therm-app.comA thermal imaging camera attachement that can work on Android smartphones is available: the Therm-App™ from Opgal (, a producer of infrared thermal imaging and near IR illumination products.

The Therm-App™ smartphone-attached thermal imager is shown at left.

The Therm-App™ IR camera is not as flat an add-on as the iPhone-fitted clip-on FLIR One™ but the Therm-App™ has a significantly higher-resolution lens ( 384 x 288 pixels vs. 80 x 60 pixels for the FLIR One™ thermal imager), offering sharper images that may be important if the images are to be enlarged or used in larger format reports. Cost for the Therm-App™ thermal imager is about $1000. U.S. Optional lenses and other attachments are available as well.

Using a clip-on such as the Therm-App™ hand it means that Android smartphone users don't have to buy an iPhone - which could be far more than the cost of the phone as one will surely also subscribe the iPhone to a phone service. This device will attach to many smartphones.

At the company contact links below we give the power, smartphone clip size range and other specifications for the Therm-App™ thermal imager. See

Infra Red Inspection Equipment, temperature, heat loss, active leak detection, moisture investigations - Equipment Suppliers

Thermal image example, Paul Probett, Incodo 2008

Therm-App thermal scanner camera smartphone attachment - adapted from

Applications of Thermography in Buildings


Continue reading at THERMAL TRACKING BRIDGING GHOSTING or select a topic from the More Reading links or topic ARTICLE INDEX shown below.


Or see THERMOGRAPHY IR Infra Red & THERMAL SCANNERS where we've report other sources of thermal imaging information.

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THERMAL IMAGING, THERMOGRAPHY at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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