Matthew Steger WIN Elizabethtown

Infrared (IR) Thermography

Infrared (IR) thermography, also sometimes called thermal photography or thermal imaging, has gained popularity in recent years in industries that deal with home energy usage and energy efficiency. This technology is very useful in finding areas of a building that are losing or gaining heat (such as due to a lack of insulation), water infiltration because of roof or plumbing leaks, overheated electrical wiring, and leaky heating/cooling ductwork, just to name a few examples. Air infiltration (air flow into a building) or exfiltration (air flow out of a building) generally has specific visual patterns that the certified infrared thermographer is trained to identify. WIN Home Inspection offers Infrared (IR) Thermography to home buyers/sellers, home owners, builders, contractors, etc.

Infrared thermograhy isn't just used to find issues in homes. It is also used by the military and police for search/rescue, by doctors to find medical problems, by factory technicians to find issues with machinery before it breaks down, and that is just a short list of uses. 

Thermography Missing Wall Insulation

The above infrared image shows an area of a home's wall where insulation is missing. 

Thermography water leak

The above image shows a hidden water leak under a bathroom's vinyl floor covering. There was no staining on the floor covering visible yet, however the IR shows an active but hidden leak from a toilet. The IR camera doesn't see water, but it sees the evaporative cooling related to the water. The leak was confirmed using a moisture meter.

Roof leak that was found in a bedroom using IR thermography. There was no
visual evidence (such as a stain), but the leak was easily found with the IR camera.

Before even going up into the attic, I could tell that there was insulation
or weatherstripping lacking at this attic access panel. The yellow/orange at the panel's
perimeter show heat.

Infrared cameras look at the amount of infrared energy that objects give off or reflects.  Infrared cameras do not use X-ray vision or night vision; both are completely different from infrared thermography.  They do not measure temperature, but instead they correlate the infrared energy detected into a picture interpreted on the camera’s screen as temperature.  Infrared energy and visible energy (visible light, for example) are in different frequency ranges or spectrums.  Every object above absolute zero (-273º C) gives off some amount of infrared energy that can be seen by the infrared camera.  Of course, all objects in our normal everyday environment are at temperatures well above absolute zero.

Finding areas of the home where heat is escaping or invading can be relatively easy for a properly trained infrared professional.  For example, in the winter, using an infrared camera to inspect a ceiling below a poorly insulated attic would show where insulation is lacking compared to areas around it by the fact that the IR camera would display a range of colors corresponding to temperatures across the ceiling.  Different issues may look similar on the infrared camera to the untrained eye, however a qualified infrared thermographer must know how to decipher the visible differences between a leak and missing insulation, for example.  Another benefit of using infrared thermography is that it can be done without using destructive means, such as putting holes in walls or ceilings.  Since infrared cameras don’t rely on visual light, they see in complete darkness.

The properly trained and qualified infrared thermography must have a detailed grasp of energy and heat transfer science as well as material emissivity. Emissivity deals with how infrared energy interacts with different materials. Infrared (IR) cameras look at a different wavelength of light outside of where humans can see. Our eyes see light in the visual spectrum whereas an IR camera sees energy in the infrared (IR) spectrum. The infrared spectrum is a lower frequency (higher wavelength) than human eyes can see.

Knowing where insulation may be lacking in an attic and exterior walls can help identify locations where improvements can be made to help lower utility costs and increase interior comfort. Many professionals who perform energy audits also use infrared thermography. This technology can also help find problem areas with electrical wiring or HVAC ductwork since both deal with temperature. An overloaded wire junction in the wall may be able to be found before it starts a fire. Unsealed or uninsulated heating/cooling duct junctions could be found and repaired to help save on energy costs.

Since water leakage into a wall or ceiling, for example, often has specific visual patterns, finding evidence of roof and plumbing leaks or even water leaking into a finished basement wall can also be done with infrared thermography. Water cools a surface due to evaporation; this cooling effect pattern is what the infrared thermographer is looking for. The IR camera doesn't see water, per se, but it sees the evaporative cooling related to the water. If a suspected leak is found with an IR camera, a moisture test should be done (using a moisture meter) to confirm the leak, assuming the area in question is physically accessible.

For infrared cameras to be effective in finding water or cold/hot air infiltration, there should be a temperature difference between the home’s interior and exterior of at least 12º F, although 18º F is even better, since thermal energy moves from warmer to cooler objects.  If a building’s interior and exterior temperatures are near the same, little energy transfer will occur and the camera will not see temperature differences in these objects.  Therefore, when an infrared thermography scan is planned for a building, the heating or cooling system should be set accordingly to achieve an interior temperature differential of at least 12º F starting several hours before the scan begins.  The best case setup would be an 18º F for 4 hours although this often not feasible in a home, especially in spring and fall. Also, should there be a lot of furniture, boxes, shelving, or even artwork on the walls in a home, these items should be moved away from the walls in order for the infrared camera to see the walls.

To use this technology properly and reliably, the user must be properly trained on how to use the infrared camera and how to decipher the characteristics of heat transfer and what he sees on the camera's screen. Again, an untrained eye could easily confuse a plumbing leak with missing insulation, or totally miss this phenomenon altogether, when looking at an image displayed on the infrared camera.

An important fact that needs to be mentioned has to do with exterior temperature and direct sunlight.  Late in the afternoon on a warm sunny day, trying to use infrared thermography on an exterior wall of a home that has had a long day of sun exposure may be tricky or next to impossible.  This situation can cause the infrared camera to provide little to no useful information about the home since the camera can be overwhelmed by the amount of infrared energy bouncing off the siding or roof and can lead to issues being missed.  Ideally, early morning tends to be the best time for doing such exterior work due to the interference of exterior temperature being less likely.  In cases of looking for a roof leak on a flat roof, for example, a few hours after the sun has set is actually best.

The reason that infrared cameras are useful in finding roof and plumbing leaks is due to the process of evaporation.  As water cools or warms to its ambient environment, energy movement occurs between objects in the process that is detectable by the infrared camera.  As one can imagine, a leak that happened a week ago (but is no longer active due to lack of rainfall) may not be detected by the infrared camera since the leaked water is now at the same temperature as its surroundings.  There is no temperature differential for the IR camera to see. If and when a leak is detected with the infrared camera, it is wise for the infrared thermographer to confirm this finding by using a moisture meter for verification assuming the stain or leak is physically accessible.

Many home inspectors use infrared cameras as a tool (either as part of their home inspection or as an add-on service), especially since the price of this technology has decreased significantly in recent years.  Infrared cameras are not new, however; this technology has been around since the 1960s.

Most of the infrared camera manufacturers, as well as some independent 3rd party companies, offer extensive infrared thermography training.  When hiring an infrared thermographer, it is critical that the customer ensures that the thermographer has been properly trained and/or certified.  The information that is displayed on an infrared camera can be very complex and can be easily misinterpreted by an untrained individual.

Infrared thermography scans are not a separate inspection option listed on the PA sales agreement (such as WDI/Wood Destroying Insect inspections and Radon Testing).  As the sales agreement is currently written, no separate option is required to be chosen by the home buyer should they opt to have an infrared thermography scan performed during their inspection contingency.  I’ve run across some confusion among home buyers and Realtors when they think they can’t have an infrared thermography scan performed because they didn’t specifically ‘opt’ to have one done on the sales contract.  If the ‘home inspection’ option is chosen, then the inspector can also perform an infrared thermography scan.  If and when the thermographer tells the client that he just found a hidden leak, missing insulation, or potential fire hazard that was previously hidden even after the most detailed home inspection, the client would be happy they invested in this add-on service.

Having the infrared thermography scan performed will likely add an additional fee to the home inspection, however, if the inspector finds an issue, this additional cost will be well worth it.

I have been trained and certified as a Level 1 infrared thermographer for several years and have performed thermography scans in many homes. In some homes, the scan will show nothing out of the ordinary. In other homes, though, I have found issues (some very serious in nature) that would have easily gone undetected by performing the basic home inspection.

I recently was called in to inspect a home for a buyer that had actually had a home inspection performed a few days earlier by another inspector. For whatever reason, the buyer opted to hire me to perform a second complete home inspection and decided to add my infrared thermography scan due to the home having a finished basement.  I found no signs of basement water entry through the foundation, but I did find a serious roof leak that the first inspector totally missed because he did not perform infrared thermography. There were no ceiling stains from the roof leak, yet, but by simply scanning the ceilings instantly showed me a leak. The roof leak was confirmed to be saturated (and thus, active) using my moisture meter. The buyer was very pleased that he hired me to perform his second home inspection and that he opted for my infrared thermography scan.

An infrared thermography scan normally adds anywhere between 20 and 50 minutes to a home inspection depending upon the home's size and what is found. Cluttered homes are more difficult to inspect since many of the walls and floors may not be fully visible. As mentioned above, if potential leaks are found with the IR camera, the inspector should confirm the leak using a moisture meter if the area of concern is safely and physically accessible.

The author of this article, Matthew Steger, is an ITC Level 1 Certified Infrared Thermographer.

Find more information about this service by visiting our Infrared Thermography Service Page.

You can find our full service list under the Services tab at the top of our website:  https://elizabethtown.wini.com

My full list of technical and home maintenance articles can be found here.

© 2014 Matthew Steger

Matthew Steger, owner/inspector of WIN Home Inspection, is a Certified Level 1 Infrared Thermographer, an ASHI Certified Inspector (ACI), and an electrical engineer. He can be reached at: 717-361-9467 or msteger@wini.com.

WIN Home Inspection has provided a wide array of home inspection services in the Lancaster, PA area since 2002. This article was authored by Matthew Steger, ACI - owner of WIN Home Inspection in Lancaster, PA. No article, or portion thereof, may be reproduced or copied without prior written consent of Matthew Steger.