December, 2017
Inspection News and Views from the American Society of Home Inspectors

Chasing Water With Thermal Imaging, Part 2


As I stated in Part 1 of this article (in the November issue of the Reporter), chasing water is what I do for a living. I’ve found thermal imaging to be an excellent tool that complements any leak-detection strategy. With the understanding that water always chooses the “path of least resistance,” we use thermal imaging to help explain the often-mysterious origins of water leaks, which may be far from the physical evidence of damage.

Thermal imaging technology has allowed me to expand my home inspection business by mapping water-related pathways with a completely noninvasive technique. Thermal imaging provides immediate visual results that can reveal the actual sources of leaks. This article details some of the ways that my company has helped clients solve “mystery leaks”, and gives you a sense of how you might use infrared technology as a way to expand and market your business.

The Path of Least Resistance
As a review, people tend to choose the path that requires the least number of steps or the fewest obstacles to achieve a goal. Computer navigation systems offer the shortest distance between points A and B, or provide a route with the least amount of traffic. As defined by, “the path of least resistance describes the physical or metaphorical pathway that provides the least resistance to forward motion by a given object or entity, among a set of alternative paths. The concept is often used to describe why an object or entity takes a given path.”

Water, of course, is known to follow the path of least resistance. Unlike human beings, water doesn’t care how long it takes to get to its final destination, as long as it travels along the easiest route. This fact is often what confuses people when it comes to understanding where a water leak originates because they commonly assume that the leak must be near the area of visible damage. Having been in the building inspection business for more than 20 years, the number of times I’ve encountered people frustrated with “mystery leaks” is huge—it’s such a common problem that, as a keyword search on the Internet, it yields nearly 10 million results.

Here are some examples from my inspection experiences:

Case 1: Infrared Testing in a Large Building
Leaks come in all sizes. For one case, we were hired by the manager of a large commercial building to solve a mystery leak. The manager retained our services in an effort to see if thermal imaging could help give a clue. Once on site, we systematically used spray racks to simulate rainfall to try to identify the source.

Leaks were occurring at three brand-new buildings at this facility. The client had complained to the builder about many leaks, noted at windows.

The builder was frustrated with the leaks coming in and had cut many holes in the walls in an effort to find the leak (left photo). Through our efforts, we were able to duplicate the leak and, as seen in the photo on right, the leakage was coming in just under the window flashing.

As we discussed in Part 1 of this article series, water often has to travel before it shows up. In this case, we needed to locate the source of entry. Thermal imaging of the building exterior helped us quickly identify an anomaly that captured our attention. On closer look, we confirmed that these anomalies were consistent with the cracks in the stucco.

As you can see in the photo above, the stucco finish was nonabsorbent (that is, it had an acrylic finish). These cracks were actually a break that allowed the point of entry. This collective of water and evaporative cooling is what we identified with the thermal view. The finish of the stucco did not allow entry (except at a crack); it also did not allow the water to escape. Water simply took the path of least resistance and bypassed the window flashing, causing water to enter the building. Case 1, solved!

Case 2: Thought to Be a Planter, Found to Be a Gutter

My company was retained after a client experienced a failed attempt to identify the true source of a leak. As seen in the thermal image above, the moisture is still there.

The living room of this large custom home showed a leak at the ceiling. Directly above this leak, a decorative planter had been placed, as you can see in the center image. The right image is the view from the outside, which is just opposite of the earlier image of the man taking a moisture reading. The contractor completely removed and re-waterproofed the planter, believing that the stain was a direct result of the planter. They repaired all the ceilings of the living room and the adjacent room, only to find out that the next time it rained, the leak was still there.

Thermal imaging of the walls showed us that the water extended above the planter (top-left image, blue arrow, at the adjacent bedroom above the round window).

Destructive testing helped confirm the thermal imaging results, which showed drenched insulation above the location of the planter. Notice the worker wringing out water from insulation taken from wall.

We took our water testing efforts to the roof. While on the roof and focusing our efforts on the upper areas, we identified what appeared to be a new gutter system installation. After the contractor was questioned about this, we were able to determine that the gutters had been installed just weeks before the initial water condition first showed itself.

How did we solve this mystery? We found that the water flowed from the roof, hit the splash block at the gutter, passed back to a supporting nail at the gutter, and then exited around a nail that entered the structure at the soffit. Case 2, solved.

Marketing Those Tools in Your Bag
To make you fully aware of the importance of advancing this technology, I must admit that, although my brain is my primary tool, my infrared camera often is my primary marketing tool. It has frequently been the reason that my company gets the amount of work that we do. I have had jobs for which my brain really did all the work, but the client raved about…the thermal imaging tool instead! Of course, I am the one who is known to have this “magic tool,” so that raving is what has led me to more referrals.

Case 3: A Leaky Shower, a Moisture Meter and a Pet Dog

The client complained that the shower leaked; however, they had not used the shower in over a year. Thermal imaging did not easily identify the condition; however, using moisture meters confirmed the elevated level of moisture at the corner of the wall (not closer to the shower as we would normally suspect).

For this case, we finally had to use another meter—our nose! What we found to be the source was not what the owner expected. Notice the arrow on left (dog bed) and notice the culprit on right (guilty!). Case 3, solved.

With the title of this article series, “Chasing Water with Thermal Imaging,” we felt it was appropriate to explain what people actually hire us to do. Many times, as described in the case studies, you can see clearly that thermal imaging is what helped us chase down the source. If you are a building professional in search of an excellent tool—not only for your bag, but to help with your marketing—an infrared camera is an excellent investment.

I often mentor new and existing thermographers so they can build their companies to be the sort that they would like to operate. Keep in mind that any business starts with what you like to do and what your talents are. If you are a home inspector, a contractor or a water remediation contractor, becoming a thermographer can be a great way to expand your business. Think of it this way: You can truly diversify your home inspection business by expanding into the forensics aspect of the stains that you are reporting on.

Peter Hopkins has operated a successful home inspection company since 1996 ( and has performed more than 7,000 property inspections. The company expanded into infrared in 2005, with the opening of SoCal Infrared (, and has found success in many areas of diversification, but specifically in the ability to diagnose moisture conditions identified during property inspections. He is the co-founder of United Infrared (, a national network of contract thermographers that includes application-specific training and business coaching in a multitude of applications related to infrared technology and other vision technologies like sewer cameras. Peter is a Level III Certified Thermographer, ASHI Certified Inspector, ICC Code Certified Building Inspector, Certified HERS Energy Rater, and trained in Equine Thermography and licensed with the California Horse Racing Board as an Assistant to Veterinarian. Peter lives in Southern California with his wife and two children. Contact Peter at 888-722-6447, email,