Is thermal imaging ( thermography ) a useful service to you?

There is a great deal of uncertainty and confusion over the use of thermal imaging for a home inspection, or other inspections.  Most of this uncertainty is from a lack of understanding of just what thermal imaging is and what it can do.  Many consumers then question if thermal imaging right for them? The answer to that question starts with another question that consumers must ask themselves.  That question is what do you expect to achieve with the use of thermal imaging?  To help you answer that question I will provide a brief description of what thermal imaging is, what it is not, how it can be used in a home inspection, and when it might not be beneficial to use or try.  We will try to remain as non-technical as possible to prevent confusion.

What is thermal imaging?  Everything in our world, including living things, emits thermal energy.  As the object increases in temperature it will increase the amount of energy it radiates.  This energy can not be seen and occurs in the infrared frequency spectrum.  A thermal imager (often mistakenly called thermal camera) collects that emitted thermal energy, converts it to a visual representation of temperatures that are provided on a display as various shades of black and white or in various color pallet schemes.  Essentially the Thermographer (the trained person using the imager) will view these representative temperature and/or pattern differences to determine if an anomaly is occurring.  An anomaly, as it relates to thermal imaging, is something that is displaying readings different than what is expected from the area being scanned.

There are two general approaches for performing a scan with thermal imaging.  One is called “qualitative analysis” and the other “quantitative analysis”.  Qualitative analysis is comparing a reading from the surface of an object with other areas of that same surface or with past experiences and knowledge of what might be expected.  With this method we look for patterns of an anomaly without regard to the exact temperatures the anomaly is displaying.  With the quantitative analysis approach the Thermographer is reading exact energy (temperature) levels and comparing those to what is considered normal for the item being scanned.  An example image is displayed below.  This an image of a water leak from a bathroom shower as recorded on the opposite side of the shower wall (in a living room area).  The water leak is displayed as the darker blue (cooler) area at the base of the wall.  The surrounding area is at a higher temperature that this area of carpeted floor.  This is our anomaly that would indicate a potential problem.  With qualitative analysis we are not concerned with exact temperatures to identify a potential issue.  Instead there is an unexpected temperature difference to indicate a potential problem.  Hence the “quality” of the area suspected as being an issue is different than the surrounding area that is not a suspected issue.  In contrast if we were to be using quantitative analysis we would be concerned with the exact differences in temperature between the suspect wet area and the dry area.

Regardless of whether qualitative or quantitative analysis is used the discovery of an anomaly always requires further checks with other means and/or equipment to verify the condition.  The use of quantitative analysis is a very exacting and time consuming effort that is used for specialty cases.  When performing the analysis on a building or structure our concern is to find potential anomalies that require further checking.  For this aspect the use of qualitative analysis is all that is needed.  In the example image below a moisture meter was used to check not only the carpeted area to determine that a potential water leak was present, but also the slightly different shaded area of the wall above the wet carpet which provides the appearance that water might also be affecting it.  The moisture meter, as well as other checks, showed that the leakage was not affecting the wall material yet.  It was originally suspected that given the shape of that wall area anomaly (it was almost a duplicate of the carpet shape) that this was just a reflection of the condition below it.  Even though the wall was not originally suspected as being affected it still must be checked.

Now that you have a basic understanding of what thermal imaging is we can quickly discuss what thermal imaging is not.  Thermal imaging is not X-Ray vision and can not see into or through walls.  In fact thermal imaging is only capturing and recording the energy emitted from the surface of an object.  If a condition occurs behind the surface of an object that causes the object’s surface to display the condition then thermal imaging can be used to display a representative image of what is behind the surface.  A good demonstration of this is to wrap your hand around an empty coffee cup.  At first the cup will possibly feel cool until your hand warms it up.  You can walk around with that cup all day and the temperature of that cup will always feel the same.  Now while still holding the cup pour some hot coffee in it.  It does not take long for the heat of the coffee to be felt through the cup and to your hand.  If you were to set the coffee cup down and pour the coffee in you would not be able to see that heat radiating outward from the surface of the cup.  This is obviously an extreme example but displays how a condition behind the surface of an object affects the surface temperature and allows a Thermographer to detect a potential issue.

Yes that was a lot of information you just read but important to help you understand if thermal imaging can be helpful to you.  The short answer is yes it can as regardless of the conditions present there are many good uses for thermal imaging in a home inspection.  However there are many conditions that must be considered to determine if thermal imaging is right for your home inspection.  All of these considerations can take volumes to discuss.  We will speak of some here but highly urge you to have your Inspector explain to you what they intend to check with thermal imaging, why, and how the Inspector intends to provide useful scans.  One of the common advertisements I read on Inspectors WEB sites is that “A free complete thermal scan is included with every home inspection”.  But are you really receiving a “Complete thermal scan”?  For example one use of thermal imaging is to search exterior walls for missing, incomplete, or settled insulation.  But did your Inspector tell you that those bookshelves, piers and headboards, pictures, tapestries, flat screen TV, sofas, and any other object blocking the wall will also block the use of a thermal imager?  Did the Inspector tell you that they have no intention of moving those items?  Another example of thermal imaging’s use is to check for electrical hot spots within the main breaker panel as well as wiring around the home.  To obtain a true picture of these though requires placing a load on the electrical system so you can scan the main breaker box for issues as well as the wiring throughout the home.  If your home uses an electric stove, electric heater, electric water heater, etc., then a partial load can be placed on the system but this is only a partial load.  What about the circuits used to service the washer/dryer, microwave, the branch circuits for wall outlets, and other such parts of the system?  Did your Inspector tell you that they won’t be running these other appliances, or running them long enough, to determine if a fault potentially exists with them?  How about in a completely empty home with nothing but the lights to run?

Thermal imaging can be a valuable service during a home inspection if it is performed properly!  As a consumer I would ask a lot of questions if you are considering paying for this service, and even more questions when the Inspector tries to draw you in with the claim of “A free complete thermal scan is included with every home inspection”!

infrared image of shower leak

Image 1

Knowledge is power, but sharing knowledge brings peace!

PS Inspection & Property Services LLC is a full service home inspection and light commercial inspection company servicing the entire Dallas/Fort Worth metroplex.  We strive to for the satisfaction of our customers in everything we do.  Our services offerings include:

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New Home Draw Inspections
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If you have an inspection need we can customize an inspection for it.  Please visit our main site at PS Inspection & Property Service LLC.


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One Response to Is thermal imaging ( thermography ) a useful service to you?

  1. litefore says:

    Very good post.