So, what is Infrared home inspection, anyway? Learn how Infrared home inspection works, what it costs, and if you should include infrared inspection with your next home inspection.
As our society becomes ever more technology entrenched, new and more advanced tools become available to the home inspector. Among the inspector’s tool belt is the infrared camera. In this article I will attempt to answer the most common and relevant questions regarding infrared home inspection, as well as a few you maybe haven’t come up with just yet. The questions I will address are:
What is thermal imaging?
So, what exactly is thermal imaging? Thermal imaging, also known as Infrared thermography, is the practice of viewing objects, components or systems using a camera that is sensitive to Infrared radiation (IR). Infrared radiation can be thought of as light that humans cannot see with our own eyes. It is also heat, hence the term thermal radiation, or thermal imaging. The terms “Infrared thermography”, “thermal imaging”, “Infrared”, and “IR” are all commonly used somewhat interchangeably. I will do the same, for the purposes of this article, so as you run across these terms in daily life, you will be used to the various nomenclature used.
How does Infrared/ Thermal Imaging work?
The topic of Infrared imaging is pretty science heavy. We’ll just cover the basics here, and skip the more painful details. You likely already know that energy travels in waves, whether it’s light, electricity, or radio signals from your favorite local station. Each of these occupies a small part of the electromagnetic spectrum. Visible light is that part of the electromagnetic spectrum which our eyes can interpret, from red at the longer wavelength end, to violet at the shorter wavelength end. It’s a little hard to imagine, but that wide range of colors that we can see actually makes up a very tiny part of the overall electromagnetic spectrum.
Is infrared a useful tool for home inspection?
Thermal imaging can be extremely useful for home inspection. We won’t go too deeply into building science here- it is a complex topic- but the home inspector who has a good grasp of building science understands, among other things, how heat and water vapor move through the building envelope and its various components. More commonly, we all know where water in a structure is normal, and where it is not. Water movement is of the utmost importance to the home inspector, as it is water that causes the most damage to buildings. Water enables the growth of bacteria, fungus and molds, leading to decay. Water can cause some materials, such as drywall, to completely disintegrate. Water intrusion also creates an ideal climate for wood destroying insects (WDI). Subterranean termites, for example, don’t eat dry wood- they need it moist. As you might imagine, looking for evidence of water intrusion is a high priority in any home inspection. Unfortunately, water itself is invisible to us. We might notice staining or a change in color of a wet substrate- such as a wet patch on a ceiling- but the water itself is not visible to us. We cannot truly tell if the stain in question is still wet, or if it has dried out. It also takes quite a bit of time, or quite a bit of water, to make a stain in the first place. Wouldn’t it be great if we could see that wet spot, before the stain appeared? With thermal imaging, we can! An Infrared camera is actually tuned to the environment such that it can detect very slight differences in temperature. A wet spot, in a room with low relative humidity, will show up as a cool spot, as evaporating water cools the surface slightly. A thermal camera can also often detect moisture in places otherwise hard to inspect, such as at the base of a toilet. An infrared camera can even detect the cooler temperature of drying paint, in the event a seller has hastily tried to cover up something that we ought to know about!
Can Thermal Imaging or Infrared See Through Walls?
I remember some show depicting a hostage situation in some warm, sunny location where a S.W.A.T. team sniper could see the bad guy through the building’s wall using a thermal imaging rifle scope. Thanks to Hollywood, this is a common misconception. No, thermal imaging cannot see through solid objects. What it can detect is temperature variances on the surface. The inspector must interpret the images, considering what is known about building science, the current conditions, and likely causes. The inspector must also be aware of the material substrate being viewed, and its reflectivity. For example, if we look at a window pane with a thermal camera, we will almost always see a ghost. Is there a ghost on the other side of the window? No, sorry, that “ghost” is a reflection of the inspector’s heat signature in the glass.
In the case of the hostage situation, the bad guy could not be seen through a wall as he paced back and forth. If the bad guy were to prop himself against the wall and stay there long enough for his body heat to pass through the wall, however, a silhouette of heat could theoretically be perceptible on the outside at some point in time. It would also become more feasible for an image to be detected if it were significantly cooler outside than body temperature, as it is the difference in temperature that is key. Incidentally, thermal imaging is also used in search and rescue operations as well as from law enforcement helicopters, where it is invaluable at night. The technology has many uses.
What Can You See With Thermal Imaging/Infrared?
Because thermal imaging is looking for heat differences, there are a lot of other things, in addition to water, that can be observed by looking into the Infrared spectrum. The inspector can identify circuit breakers in the electrical service panel that are hotter than the others. The approximate temperature can be determined as well, giving evidence as to whether the circuit is heavily loaded, or perhaps the breaker is bad. A too-hot wire inside a wall can sometimes be observed, indicating circuits that were improperly wired. This can happen when a multi-branch wire circuit (MWBC) is improperly connected into the panel, which puts way too much voltage on the neutral conductor- a very serious fire hazard. Wiring MWBC’s incorrectly has historically been so common that the use of MWBC’s, although legal, is now highly discouraged. Similarly, radiant heaters can be tested in rooms with this feature, as the warm conductors will be visible on Infrared. The home inspector can also see voids in insulation, both in walls and ceiling, by observing the temperature difference at those points. Additionally, Infrared inspection can sometimes discover sever termite infestations by detecting the moisture and missing material, such as in a wall. There are other uses as well, but these are the most common.
Is There Anything That Thermal Imaging Cannot See?
Equally important to understanding what can be seen by a thermal camera is understanding what it cannot see. As already mentioned, thermal imaging cannot see through walls, and does poorly on highly reflective surfaces such as glass. It also requires a temperature differential, in order for anomalies to be seen by the home inspector. For example, let’s consider a roof. Imagine a flat roof that has a slightly low spot that appears to hold a puddle from time to time. The home inspector is going to try to determine if there is a leak present under or near that puddle, or if the water evaporates away harmlessly. If, when viewed from above, the water is the same temperature as the roof, nothing will stand out on Infrared. If the inspector can view the roof from underneath, and the temperature of the roof, the water, and the attic below the roof are the same temperature, the inspector may not see anything on thermal imaging there either. If water is leaking into the attic and evaporating, however, a cool spot may be evident. Due to the complexity, the home inspector needs to be cognizant of temperatures both outside and inside, relative humidity inside, and an idea of how fast or slowly those temperatures are changing at the time of the inspection. For this reason, the first observation a home inspector will make is the presence of a “temperature anomaly” visible in IR. The inspector will then rely on his or her understanding of building science and environmental conditions to arrive at an interpretation of the anomaly discovered, and whether it is insignificant or should be reported.
Do All Home Inspectors Do Infrared Home Inspections?
While the use of Infrared is slowly gaining traction in the home inspection industry, it is far from common as of the date of this writing. For the home inspector, thermal imaging represents a significant cost outlay. Infrared cameras are quite expensive, typically running in the thousands of dollars. Advanced education is required to learn how to use Infrared imaging, and an advanced understanding of building science, along with experience, is needed to accurately interpret the images seen. Just as important as recognizing issues is recognizing what is NOT an issue. For example, room corners at wall/wall and wall/ceiling junctures will look cool. This is normal, caused by a non-flat surface being interpreted by a computer designed to look at flat objects. In addition to the high costs of equipment and education, the demand from consumers for thermal imaging remains relatively light. The reasons for this are twofold: for one, most consumers are not aware of thermal imaging in home inspection (hopefully you won’t be one of them after today!). They might even think the home inspector offering it as an add-on is trying to hoodwink them. Second, there are inspectors who are equipment minimalists. Their work is easy to spot, if you know what to look for. They don’t carry ladders for accessing the roof (looking from the ground is acceptable, and legally adequate). They might call out a moisture stain in the attic, but they don’t test it because they don’t have a moisture meter. They will call out an open electrical splice in the attic, but they don’t mention if the wires are energized (“hot”), or if they are dead- because they did not bring an electrical tester with them into the attic to find out. These types of inspectors will have little to no interest in offering thermal imaging; an Infrared camera costs hundreds of times as much as the tools they already don’t use. And to be fair, it is difficult to make a business case for investing in thermal imaging equipment when demand is so light. It takes quite a long time to earn enough income from infrared home inspecting to pay for the equipment.
How Long Does An Infrared Home Inspection Take?
Adding thermal imaging to a home inspection that you are going to do anyway adds only a relatively small amount of time. The home inspector can fairly quickly scan a room and determine if anything in the Infrared spectrum looks off. More time would be spent documenting any findings, and potentially digging deeper to find the cause. On the other hand, to go into a home and do just a thermal imaging scan, absent of a full home inspection, would take quite a bit longer. Ultimately the time needed would depend on the scope of the inspection. Is the inspector going to look at the roof, the attic, and inside the house? Will the inspector also be removing the front cover from the electrical panel to inspect the breakers and related equipment? Will the inspection include going under the house (if on crawl space or basement) and checking for plumbing leaks and other issues? The time needed for a standalone thermal imaging / Infrared inspection could end up being considerable, and at the end of it a report must also be generated. If you only have a limited concern, then it might not take much time at all. Ultimately, you would need to discuss this with your favorite Infrared inspector, who can give you a better idea of what to expect.
Should I Get An Infrared / Thermal Home Inspection?
The purpose of this article is to inform you, the reader, so that you can make a good decision as to how important you feel an Infrared inspection is to you. Nobody can decide that for you. While the author personally feels that thermal imaging is a highly valuable technique, that is in part because he had a very bad experience on a home purchased without it. Your experience could be different- hopefully it is. It is entirely possible to look at a home through Infrared, and find nothing additional that could not be observed without it. Does that make it worthless? Not in the author’s opinion- but again, that is up to you. One thing to consider, though, is this: while an inspector may charge a little extra to include Infrared imaging with your home inspection, to come back later and do just a thermal imaging inspection would be almost like doing another entire home inspection all over, and the cost to do so would be reflective of that fact. If you think you might want to have it done later, it will almost certainly be significantly cheaper to add it to your regular home inspection instead.
How Much Does An Infrared Home Inspection Cost?
The cost of an Infrared home inspection will depend a lot on how much time will be required to complete the work. There are two general factors at play: how big is the house, and how much of it do you want the inspector to look at? Most inspectors have a sliding scale relative to the size of the job. Do you want a thermal imaging home inspection from top to bottom, or is there a certain thing in particular that is of concern? You could certainly limit the scope of the inspection to just the attic, for example, if that is all you want. If you are already getting a regular home inspection, though, and you are considering adding on an Infrared inspection as well, the additional cost will typically be quite little. Your inspector simply scans everywhere he looks twice- one by eye, one by infrared camera. Anything discovered will likely lead to additional digging, as well as more information on the report, so you shouldn’t expect it to be free. A rough rule of thumb might be approximately 25-40 percent of the price of the regular home inspection if the infrared inspection is done at the same time as the regular inspection. Done separately, at a different time, an infrared home inspection would likely cost just as much as the regular inspection. You can save some money by doing it all at the same time.
Can I Infrared Inspect My Own Home?
By now, you probably already know the answer to this question. Infrared cameras are very expensive, easily five times the cost of a professional home inspection. Extended education and training are required to know how to optimize the camera’s function, and most importantly, how to interpret what is being seen. It would be neither cost-effective to DIY this part of an inspection, nor would the layperson’s conclusions likely be accurate. There simply is no substitute for having an experienced home inspector, who knows his or her equipment and has a good knowledge of building science, do a thermal imaging inspection of your home.
In conclusion, thermal imaging / infrared thermography is a valuable tool to the home inspector, giving insight into the otherwise invisible. Since home inspections are by definition “a visible only, non-invasive inspection”, an infrared camera is a great way to see more than we could otherwise. There are many positives to including this service in your next home inspection, and few if any downsides. I hope you have found this article informative. If you have any questions, feel free to contact me, and I will do my best to answer any other questions you may have.
About the author:
John Behling is a Certified Property Inspector and Certified Infrared Thermographer. He is the lead Home Inspector at Deepli. His passion for thermal imaging comes from a very personal, very costly experience which also became the driving cause of his desire to inspect homes for other people, to help them avoid similar experiences. When he is not looking for water in other people's homes, he can often be found playing in it. He is an avid kayaker and canoeist, and also enjoys fishing, diving, and sailing.
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