What thermal imaging leak detection can and can't find
An infrared camera measures the surface temperature of whatever it's pointed at and displays it as an image. It shows the effect a leak has on the surface in front of it. The water itself, and the inside of the wall, stay invisible to it.
It works well for:
- Hot water lines under a slab. Leaking hot water heats the concrete, and the floor above shows a warm patch that's brightest near the leak.
- Wet drywall and plaster. Damp material cools as water evaporates from it, so a wet area reads cooler than the dry wall around it.
- Tracing hot pipe routes. Running hot water for a few minutes makes the line show through a floor or wall, which tells us where the pipe is.
- Showing how far water has spread across a ceiling or down a wall, including areas with no visible stain yet.
It doesn't work well for:
- Cold water leaks under concrete. There's little temperature difference to see.
- Deep or well-insulated pipes.
- Leaks behind tile over thick mortar, cabinets, or mirrors. Shiny and reflective surfaces give false readings.
- Buried yard lines and pool plumbing. Those are found by listening and pressure testing.
When to use infrared leak detection
Thermal imaging is most useful when you have a symptom but no clear location. Typical situations:
- A floor that feels warm in one area, or a pet that keeps lying on the same patch of tile.
- A water heater that runs far more than it used to.
- A stain on a ceiling or wall, and you want to know how big the wet area really is.
- A musty smell in a room with no visible damage.
- A wall that feels cool or slightly damp to the touch.
- A recent leak that was repaired, and you want to check that the area is drying.
How a thermal imaging leak inspection is done
- Meter test first. Before scanning, we check whether the property is losing water at all. A thermal image means much more when we know a pressurized line is leaking.
- Set up the conditions. Thermal imaging needs a temperature difference. For a suspected hot line leak, hot water is run or the system is left pressurized. For damp walls, the room is kept at a steady indoor temperature.
- Scan the surfaces. Floors, walls, and ceilings in the suspect area are scanned slowly from several angles to rule out reflections.
- Read the pattern. A leak has a characteristic shape. A hot slab leak is a rounded bloom with a hot center. A pipe is a straight line. Wet drywall has an irregular edge that follows gravity. Framing, ducts, and sun on a wall all have patterns of their own that need to be ruled out.
- Confirm with a second method. A cool patch on a wall is checked with a moisture meter. A warm bloom on a floor is checked by listening on the slab and by pressure testing the hot side. We don't mark a leak on a thermal image alone.
- Mark and explain. You see the images, and we mark the location and tell you what was confirmed and how.
Thermal imaging is one tool among several. On most jobs it's combined with acoustic listening and pressure testing as part of our wider leak detection in Tucson.
How Tucson heat affects thermal imaging accuracy
Thermal imaging depends on contrast, and for much of the year Tucson removes it. Summer highs run around 100 degrees.
A west-facing wall in the afternoon is hot all the way through, an attic is far hotter than the rooms below, and a slab near a sunny patio door is warm with no leak anywhere. Tucson's incoming "cold" water is also warm in summer, so a cold line shows even less than usual.
In practice this means 3 things for a scan here:
- Time of day matters. Exterior walls and ceilings under a hot roof read best in the early morning, before the sun loads them with heat.
- Air conditioning helps. A house that has been cooled steadily for several hours gives clean contrast against a hot water leak or a damp wall.
- Sun patches get ruled out. A warm area by a window or sliding door is checked again after it has been shaded.
If someone scans your sun-heated wall at 4 in the afternoon in July and declares a leak from the image alone, be skeptical. Ask what else confirmed it.
What affects the cost of thermal imaging leak detection
- Area to be scanned. One bathroom wall is a short job. Every floor in a large house isn't.
- Whether imaging alone answers the question. If the scan points clearly to a spot and a second test confirms it, the job is quick. If the leak is on the cold side or under thick flooring, other methods take over.
- Floor and wall coverings. Tile and bare concrete show heat well. Thick carpet, rugs, wood floors, and cabinets hide it.
- Access. Furniture against walls and stored items on closet floors have to be moved for a clear view.
- Preparation. A house that's already at a steady cool temperature can be scanned right away.
When a leak can't wait for a thermal scan
Thermal imaging is a diagnostic step. It comes after the water is off. If water is coming through a ceiling, running out from under a wall, or spreading across a floor, shut off the main water valve first.
If a ceiling is sagging, keep clear of it. If water is near outlets or light fixtures, turn off the breaker for that area.
Then call. Once the water is off and the situation is safe, a scan shows how far the water has travelled, which is useful for whoever dries and repairs the area.
How to prepare for a thermal imaging visit
- Run the air conditioning or heating normally for several hours beforehand so indoor temperature is steady.
- Leave the water heater on and the water supply on, unless water is causing damage.
- Close blinds on sunny windows in the area to be scanned.
- Move furniture and rugs away from the suspect wall or floor if you can.
- Don't run a fan or heater on a damp spot right before the visit. It changes the surface temperature.
After the leak is located, the repair is done by the plumber or contractor you choose. Leak Detective doesn't make repairs.
A follow-up scan 1 to 2 weeks after the repair can show whether the area is drying. For hot-side leaks specifically, see hot water pipe leak detection.
Thermal imaging leak detection questions
Can a thermal camera see a leak inside a wall?
Not directly. It shows the temperature of the wall surface.
Wet drywall usually reads cooler, and a hot pipe reads warmer. Those patterns show where to look, and a moisture meter or pressure test confirms whether there's a leak.
Can thermal imaging find a slab leak?
It often finds hot water slab leaks, because the leaking water warms the floor above. Cold water slab leaks rarely show, and those are located by acoustic listening or tracer gas instead.
Is thermal imaging accurate in a Tucson summer?
It can be, with the right conditions. Sun-heated walls and hot attics reduce contrast, so scans are best done in the morning or in a house that has been cooled steadily. Any finding is confirmed with a second method.
Does a thermal scan damage anything?
No. The camera only takes images. Nothing is cut, drilled, or sprayed.
Is a cold spot on the thermal image always moisture?
No. Missing insulation, an air leak, an AC duct, or a metal stud can all read cooler. That's why a cool area is checked with a moisture meter before it's called a leak.