Infrared or Thermal Imaging Cameras – Finding Moisture Using Infrared Light

Infrared cameras are sometimes called IR or thermal imaging cameras. Prices have dropped considerably in recent months, putting thermal imaging technology within the financial reach of many more cleaning operations.


Because of its advantages, eventually, most everyone in the cleaning and restoration business will be using this technology as frequently as we use moisture meters. So, let’s go over a few things that might help you decide what’s best for you.
The Technology
Infrared radiation is an energy wave that is a little longer than the visible light wave. On the electromagnetic spectrum infrared has a lower frequency than the red part of the visible light, thus the designation infra (below) red. Hollywood has departed from the science of this technology and portrayed it as something that can see through walls and clothing. Thankfully, IR cameras do not see through walls or clothing. If they could, the technology would probably be useless as a building diagnostic tool, since we would not know whether we are looking at the interior wall, exterior wall, or the building next door.
For the purposes of this discussion, we are talking about radiation in a bandwidth with wavelengths of 7 to 15 microns. So, what does the camera “see”? A good guide to remember is that the IR camera “sees” the same surface your eye sees. It is detecting, with few exceptions, only infrared radiation coming off of and from the specific surface your eye is observing. All surfaces we look at emit and reflect infrared radiation.
In some cases infrared radiation transmits through a surface. An example would be thin (1 to 10 mil) plastic, regardless of the color. However, infrared radiation – in the 7 to 15 micron bandwidth – does not transmit through glass. This means an IR camera cannot pick up radiation from objects on the other side of glass.


Learning to use an IR camera is not hard. It is different, though, and requires training in the physics of infrared, principles of thermodynamics, and the mechanics of the camera.
This technology does not directly detect moisture, missing insulation or air leaks. Good cameras are incredibly sensitive to thermal differences. There is a thermal difference where evaporative cooling is taking place and in certain cases when there is missing insulation or air leakage. These conditions can result in expensive problems for the building owner. Many of you are in the business of solving commercial and residential building problems. The faster and more accurately you can solve and document these problems, the more successful you are. That is why IR cameras have turned out to be a highly successful tool for those in the water-damage restoration industry.
Solving the Moisture Problem
The principle that allows us to locate moisture on the interior walls is evaporative cooling. Evaporative cooling can be very slight; there may only be a 1ºF temperature difference from wet to dry. A good IR camera will easily show even that slight temperature difference.
Let’s say a customer calls and is in a panic. They just arrived home from being gone a couple of days. A pipe froze and due to a subsequent leak there is standing water in the family room at a depth of about 1 inch.
Step one is easy: extraction. But we cannot solve the remaining problems until we identify what is wet. The process of finding all areas with moisture issues can be a long and tedious task when using only a moisture meter. The thermal imaging camera quickly and accurately shows all relevant thermal differences. The investigation results in the preliminary determination of the problem. It might be moisture, it might be missing or compromised insulation on a cold day, or it might be air leakage on a cold day. All three of these issues can look the same on the thermal imaging camera when investigating the interior of the building on a cold day. So the IR camera needs to be used in conjunction with the moisture meter to quickly and accurately verify the presence or absence of moisture.
Once the moisture has been located and verified, the process of drying can begin or be modified. As drying proceeds, there is a need to monitor the drying process. There’s no better tool to monitor drying than an IR camera. The areas that are drying and those that are not are easily located; air movers can then be readjusted, and the drying process continues more efficiently.
Customer confidence is valuable and critical to growing a business. The IR camera also allows you to better document the drying process by taking IR images that can be used in your report. And, as the old saying goes, “seeing is believing”. When the customer observes you using the IR camera their confidence level goes up immediately. The kind of documentation that is generated with IR technology is also a good risk management tool. We have seen numerous cases where restorers are accused of having failed to adequately dry a structure or its contents.
With “before” and “after” IR images, showing the progress of the drying project, you can better document that, at the time you left the project, the structure and the contents were dry. Those images can save you a lot of stress, not to mention a lot of money.
What to Look For
Although there are many differences in features from one camera to another, some of the items to pay attention to include detector size; voice-memo recorder capability; number of palettes; level and span adjustments; battery time; method of saving images; weight; drop test ratings and so forth.
One of the most important features is noise equivalent temperature differential (NETD), or temperature sensitivity. The lower the NETD number, the better (e.g., 0.07ºC is more sensitive than 1.0ºC; 1.0ºC is more sensitive than 1.5ºC). This is important because evaporative cooling results in a small temperature differential, especially toward the end of the drying process. The faster the moisture evaporates, the larger the temperature differential (about 4ºF or 5ºF). As the evaporation slows down the temperature differential becomes smaller (about 1ºF or 2ºF) and you’ll need a very sensitive camera to monitor it. The higher the NETD, the grainier your image will appear and can result in missing some very slight thermal differences.
It’s also important that you take time to learn about the software that comes with the camera. It’s best to get a full post analysis software program that enables you to work with the palettes, the level, the span bar, comments, annotations, and reports. Some cameras come with very basic software and you must pay extra for full post analysis software. Be sure to find out exactly what you are getting.
Another expense to take into consideration is training. You can read the user manual but that won’t prevent you from making costly mistakes. I strongly urge you to take a training course in the physics of infrared and the principles of thermodynamics so that you can use the camera responsibly and not get into trouble. If you are in the restoration or remediation business, you don’t need a course in industrial and electrical applications. You need a course in moisture investigations and building envelope investigations.
To be competitive the professional water damage restoration company will need to consider seriously the addition of the IR technology. It may turn out that the most expensive thing you can do is to decide not to use IR.


Adapted and reprinted by permission of the author and ICS Cleaning Specialist magazine.

Jim Holland is the president of RestCon Environmental, a division of Restoration Consultants, Inc. He is a California-EPA registered environmental assessor, an OSHA-authorized instructor, and a nationally recognized consultant, instructor, and author. E-mail Jim at [email protected]