(UPDATED) Do you recognize the device is in this photo? It’s a camera used for roof thermal imaging.
A trained Sentry Roof technician is using it to locate moisture that may be trapped in a roof that’s scheduled for replacement. By identifying and quantifying any areas of wet insulation underneath the membrane, we can reduce uncertainties related to the project scope for our clients and know the exact amount of materials to have on hand for re-roofing. All without having to cut into the roof.
Wet insulation needs to be replaced because it’s no longer doing its job. It increases the cost of heating and cooling a building, and it also degrades other roofing materials. Dry insulation, on the other hand, can often be reused.
How thermal imaging cameras work
A thermal imaging camera can “see” heat.
All objects have heat (thermal) energy. A thermal imaging camera can detect that energy even though it’s not visible to the human eye. Visible light is only a small part of the electromagnetic spectrum — thermal energy, or infrared radiation (IR), is part of the spectrum that we can’t see. Unless we have special tools, that is. By taking IR readings and converting them into a visual image, or a thermogram, thermal imaging cameras allow us humans to “see” heat, too.
Thermal imaging camera sensors can even detect differences of one-hundredth of one degree. This sensitivity is an important aspect of thermography because it allows for fine-tuned images. Since all objects absorb, reflect and (sometimes) transmit energy at different levels — and different materials give off heat or cold energy at different rates — thermography needs to be properly understood to interpret thermograms correctly.
It takes training to understand how thermography works, how to capture the information, how to interpret the results, and how to use it properly for commercial roofing applications.
Thermography compared to other types of tests
Before thermography, to find moisture underneath the roof’s surface you needed to take a core sample. Core sampling is called a destructive test because it involves cutting into and through the roofing layers until the structural roof deck is reached. Core samples are typically used to identify the materials that are part of a roof assembly, identify the slope of the roof, or diagnose problems with the roof, including wet insulation.
Thermography, on the other hand, is a nondestructive technology that leaves the roof intact. It can be performed in a single day — or night, rather. Since water heats more slowly than other substances, on a sunny day wet insulation will be cooler than the surrounding dry areas. At night, the opposite is true — wet insulation will be warmer than dry insulation. For the most accurate results, it’s better to conduct thermal imaging at night when the sun is not an issue. It’s also best to conduct thermal imaging when it hasn’t rained for a day or two for the most accurate temperature readings and when it’s not windy because air movement can displace heat.
Still, despite highly accurate thermal imaging technology, sometimes your roofing contractor will want to take a core sample to confirm the results of thermography before starting a repair or re-roofing project.
Thermal imaging for roof leak detection
In addition to providing scientific data for roof replacements, thermal imaging cameras can be used to locate roof leaks — even small ones. Finding the source of a roof leak can be tricky so having the ability to detect moisture underneath roof membranes, in ceilings, or behind walls — and to detect leak pathways — can sometimes pinpoint problems faster and more accurately.
If you have a metal roof, thermography can also be used to find hidden corrosion.
Knowing exactly where a roof leak is located or where corrosion has occurred can provide significant cost savings. Why spend money to repair or replace areas of your roof that aren’t really a problem?
Hiring a trained professional
Knowing how to use a thermal imaging camera takes training. Not only do you need to know how to use the technology, but you must also be able to interpret thermograms and explain them to clients. There are several levels of training courses available — choose a roofing contractor or consultant with advanced training in thermography so you have confidence in the results and the decisions you’ll make based on them.