Q: Why use a sUAV for infrared thermal roof inspections?
A: Infrared thermal imaging has been the standard for inspecting flat roofs for years. The typical method, as laid out in ASTM C1153 – 10(2015), describes a 2 to 3-man crew physically walking the roof after sundown with a hand held thermal camera. Using the thermal camera, they search for “hot spots” where the moisture under the roofing material has kept the roof from cooling as fast as the areas of the roof where it is dry. The theory behind the method is sound, but there are several limitations related to the way the data is collected and displayed. First and foremost is safety. Because the inspections have to take place after sunset, the roof is often dark. Compound that with the fact that the camera operator is concentrating on capturing images, and it is easy to see how any air conditioning, electrical conduit, vent pipes, or plumbing could become tripping hazards. The answer has been to take an extra assistant or two up on the roof with them to make sure they don’t trip or fall off the roof. This does make the process safer, but it is still inherently dangerous, and the added labor will increase costs. Secondly, the point of view (POV) from a low resolution thermal camera on a 1,000,000 + sqft roof will give a very limited window of the roof in its entirety. For that reason, it is almost impossible to tell from the photos exactly where or how big the suspected leaking area is. To combat that, the inspection team will usually use spray paint to mark and catalog the area. Again, this works as an okay solution, but it leaves you with a limited ability to see a larger view of the roof to determine the actual size of the leaking area, or the percentage of the roof that has water intrusion. This is a very important data point to know when trying to make an intelligent decision as whether or not to repair or replace a damaged roof! Another issue presents itself when you dig a little further into infrared thermal imaging theory. Without getting too complicated, the best location to measure the temperature of a surface is at a direct 90-degree angle. When walking on a roof holding a camera forward facing, an inspector is lucky to be at a 45-degree angle, and can easily be at up to a 30-degree angle. When you are trying to measure temperature changes that can be only a few degrees F, this is not ideal.
By contrast, thermal imaging equipped sUAVs negate almost all of these limitations. Flying directly over the building offers many improvements over traditional methods. The cameras are able to capture data at a 90-degree angle to the roof, giving much more consistent and accurate data across the image. Being high above the building also allows the operator to capture a much larger field of view (FOV), giving a better overall view of the entire area, making it easier to visualize and estimate the total area of the roof’s leaks. Once a suspect area is located, the sUAV can be flown closer to the building to get higher detailed images of the possible leak. GPS data can also be added to further help locate the leaking area on very large structures. Aerial thermal imaging can make the job of inspecting larger roofs many times quicker than traditional methods. An obvious benefit of the increased inspection speed is being able to offer more reasonable pricing because of reduced labor costs. A less obvious benefit is that even the largest roofs can be scanned in one evening in that optimal window of time following sunset but before the wet sections of the roof have been allowed to cool to ambient temperatures. The longer the roof has to cool, the more difficult it becomes to detect small variations in temperature.
Q: Great, so why should we choose Aerial Revolution LLC for our Infrared Thermal Roof Inspections?
A: The team here at Aerial Revolution feels that we offer a few added benefits, that set our thermal roof inspections apart from other companies. First off is the equipment. We use some of the highest resolution, highest sensitivity fully radiometric thermal cameras in the industry. Our systems are professionally calibrated using one of the highest quality laboratories in the country, using over 1 million dollars’ worth of specialized equipment that is able to calibrate from -60 degrees Celsius, all the way to 3000 degrees Celsius. All accurate to within 0.001 degrees! We are able to have our equipment calibrated specifically for the application of roof inspections, even further increasing their sensitivity in the needed range. Our systems also offer the ability to manually control all aspects of the thermal camera. This is important because it allows us the ability focus in on the temperature range of the areas of the roof where we are looking for moisture. If left on fully automatic, which is typically the only available method for most sUAV mounted thermal cameras, the image can be knocked out of the very narrow proper range because of hot spots in the FOV like hot air conditioner condensers, warm electrical panels, or hot vents. By manually setting the image, slight temperature variations can be seen much more clearly. We also try to only capture thermal images AFTER the sun has set and the dry areas of the roof have had time to start cooling. This begs the question; why wouldn’t everyone wait till dark to start imaging a roof?! The reason is that unless you have the proper waivers from the FAA, it is illegal to fly a drone commercially after dark. Having a properly equipped drone along with a FAR 107.29 Daylight Operation Waiver from the FAA, we are allowed to legally and safely fly our drones after sunset. Having ultra-high end equipment, and the knowledge of how to operate it, we feel we have set ourselves apart from the competition, giving our customers the highest quality data in the industry.