Using a Thermal Imaging Camera to Locate Moisture in a Commercial Flat Roof

Thermal imaging cameras can create detailed maps of commercial low-slope roofs, showing where excess moisture is trapped, where the source of a leak may be, or where there is soaked or compromised insulation. Roofing professionals scan the roof, taking images to compile into a composite map, or they take an aerial image of the whole roof. These thermal images narrow the search for water intrusion, without damaging or puncturing the roof, saving time and pinpointing areas for repair.

An infrared professional must wait for just the right conditions to scan the roof. Depending on the climate and current weather conditions, there are two options a thermographer may employ: a hot scan and a cold scan.

For a hot scan, outside temperatures must be above 10 degrees C (50 degrees F) and sunny. Without sufficient heat, or with too much cloud cover, the roof will not absorb enough heat during the day to show clear results on the scan. This heat absorption is called “solar loading.”

Additionally, it is not recommended to scan after a recent rain. If the roof is wet from rain, it will be challenging or impossible to tell if the moisture revealed on the scan is from the rain or from a leak. The same principle holds for dew. If the dew point is reached, and condensation forms on the outside of the roof, it will be hard to tell the dew from internal condensation.

As long as it is a warm, dry day, the scan can be performed in the early evening. As temperatures drop at night, the roof will begin to unload its heat; but the soaked areas will hold their heat longer, so they will appear brighter on the scan. The scan must be performed quickly. Depending on the rate of temperature change, even the wet areas of the roof can quickly lose the heat that the scan detects. Ideally, the scan will be completed before this happens; but, if not, it must be resumed again another night.

In cold climates, achieving these warm and dry conditions may not be possible. Instead, building owners in these areas can perform cold scans when the temperature is 10 degrees C (50 degrees F) or less. Instead of relying on the sun for solar loading, this method relies on the internal heat of the building to warm up the roof. It may be necessary to increase the temperature inside the building for a short period of time to make this difference more dramatic.

No matter your climate, an experienced thermographer can guide you to help choose the ideal conditions.