When water intrudes into a roofing system, it can be difficult to trace its source. Water can move both vertically and horizontally within a building, and the multiple layers of building materials on a commercial roof can complicate leak detection.
Professional roofers use thermal imaging (infrared imaging) to quickly trace the path of water and determine where roof leaks start. In this article, we’re going to take a detailed look at how infrared imaging is used to determine the source of roof leaks, particularly in commercial buildings.
What is infrared imaging?
When an object is heated, it emits infrared radiation, which can be measured with a thermal camera. The camera measures heat, allowing it to see through walls, insulation, and structural elements. The brighter the image, the more heat there is in an area. Thermal cameras produce black-and-white images, but software adds color, making them easier to interpret.
How does infrared imaging determine the source of roof leaks?
When there’s a roof leak, moisture gets under the roofing material, dampening the roof layers, including the insulation. Wet insulation and other materials absorb more heat during the day and release it more slowly at night than dry materials. When a thermal image is taken early in the evening, after temperatures have cooled, wet areas will be clearly visible.
The varying colors in an infrared image show the temperature differences between building materials. Some roof components, such as HVAC equipment, roof drains, and other reflective materials, will appear warmer in every image. A professional can identify these heat sources in advance, ensuring the image is interpreted correctly.
Roofers use these images to trace the path of moisture through the roof and into the building interior. These findings are then confirmed using a nonpenetrating moisture meter that detects moisture without damaging the membrane. A thermal scan helps building owners identify where a leak starts, how much it has affected the roof and interior, and where the roof assembly remains intact.
When can a thermal scan be performed?
The conditions must be just right to perform a thermal scan correctly and determine the source of a roof leak. In colder climates, such as Wisconsin, we often use a cold-scan method that relies on the building’s interior heat to warm the roof and its components. The interior temperature is briefly raised to ensure the roof is warm enough and that roofing components can absorb as much heat as possible.
When outside temperatures are warmer (above 50 degrees F) and there is plenty of sun, a hot scan can be performed. This type of scan relies on external heat to warm the roof and its components. The scan is performed in the early evening, as the outside temperature begins to drop.
A scan cannot be performed after it rains, as it makes it difficult to distinguish moisture in the image from rain or a roof leak. Also, temperatures must be above the dew point to avoid condensation on the roof.
Commercial roofing systems compatible with thermal scanning
Not all commercial roofing systems can be evaluated with a thermal scan to identify the source of a roof leak. Certain materials make it very difficult to determine the location of a leak.
Overall, built-up roofing and heat-welded membrane roofing systems (such as TPO and PVC) are ideal for thermal imaging. However, the following are considered incompatible with moisture scanning:
- Concrete decks
- Green roofs
- Roofs with lots of ballast or rock
- Metal roofs
- Foam glass and closed-cell foam insulation
- White or light-colored roofs
- Foil-faced insulation
- Roofs that are insulated under the roof deck
If your roof assembly contains these materials, alternative moisture-testing methods are available.
Benefits of using infrared imaging when searching for roof leaks
- It’s a non-destructive test that doesn’t damage the roof, structure, or insulation
- It provides early leak detection, before other signs of a leak develop, preventing additional damage
- It’s relatively inexpensive when compared to other leak detection methods, which may involve cutting into the roof assembly
- It saves time and can be done quickly
- Pinpointing the exact location of a leak, it allows for more accurate repair pricing
- It helps restore energy efficiency by locating wet insulation, which isn’t as effective as dry insulation
Even if you don’t have a current leak, it’s recommended that you get your roof scanned at least once a year. This will help you identify moisture issues before they impact building performance and cause widespread damage. It is also beneficial to get your roof thermal scanned after a storm. Some roof warranties and property insurance policies may also require you to perform thermal scans more frequently.
If you need help diagnosing a roof leak or want to schedule a preventive thermal scan, contact us today.