The Inside Outside Guys: Leak Detection – Where is That Water Coming From?

By Ken Calverley and Chuck Breidenstein

DETROIT, September 2, 2021 ~ Decades ago, the Inside Guy was called by a real estate broker to check on a home being prepped for a buyer.

It seems there was a periodic leak that showed up as stains on the ceiling drywall. The broker needed a solution and the Inside Guy thought he could provide it. After six months and three “fixes,” the problem still was not solved so the Guy turned to a then- new technology called infrared scanning.

Within a week the thermal imaging technician had been on the site and was able to trace the source of the intrusion – a missing piece of counter-flashing on the east side of a large masonry chimney.

Water only came in when a storm came out of the east, then it followed some attic framing to a point above the living room 25 feet away! We often see builders spraying water against siding and windows and homeowners dapping gallons of tar on roofs to pinpoint leaks that can’t be found.

Tracing leaks has become an avocation for many of our listeners this summer as we have had numerous large rain events. The issue described above is typical in many buildings where the actual source of a leak is far removed from where the water “shows up” in the finished area.

The Guys have had countless emails from frustrated listeners who have hired first a roofer, then a siding professional, then a gutter guy, etc. to “cure” a leak with no success.

The Guys always say if the only tool you have is a hammer, then everything looks like a nail. The same thinking applies with many “specialists” you might hire. Their expertise and range of thought is often limited to what they do every day.

Our advice to most of these homeowners is to call an infrared specialist. Once you find the actual source of the water, you can take steps to solve it.

Infrared scanning is known by many names, including thermography and thermal imaging. As the names suggest, it detects and measures differentials in heat signatures produced by various materials in varying environments.

If you place your hand on a table for a few seconds and remove it, an infrared camera viewing the table will clearly display the heat signature left by your hand. Point the camera at a fluorescent light fixture and you will “see” inside the fixture housing where the magnetic ballast is using copper coils to control the current to the bulb.

The thousands of potential applications for thermography include veterinary medicine — Did you know a cow with “hot” hooves is sick? Or dentistry, where dentin shows a different heat signature than enamel, and even ecology, where thermal scans in Australia were used to “see” which houses were most susceptible to infestation by malaria-carrying mosquitoes.

In the building industry, thermal imaging is used to conduct energy audits and roof inspections, provide moisture detection, scan electrical systems for faults and even to scan structural masonry walls for defects.

Keep in mind, this technology takes experience to understand and apply. An infrared scan of a roof leak taken at night might appear to contradict the same location scan taken in the heat of the day.

You can also do some detective work of your own when evidence of a leak occurs. Did we have a rain event? Was it wind driven from a specific direction? Is the water stain on a ceiling below a bathroom or kitchen where a leaky pipe might be the culprit? Are blocked gutters or downspouts depositing water right at the foundation line or causing water to back up into the wall frame at the roof line?

Rather than a rust colored stain on that ceiling drywall, you may note indents where fasteners where used. These often indicate swelling of the drywall or plaster due to water.

Regardless of how or where a water intrusion manifests in the building, know that the best first step is to locate the source.

As always, you can find professionals for thermal imaging and for repairs to the structure at

For more housing advice, listen to the “Inside Outside Guys every Saturday and Sunday on News / Talk 760 WJR from 10 a.m. to noon or contact us at