Thermal Technology for Roofing Applications

We The thermal technology of the pioneering infrared was recently discussed and how roofers can use it to offer inspection services. John Anderson, product manager for security solutions for FLIR systems, shared his knowledge here:

Roofing Technologies (RT): Let’s start with the basics. What is thermal imaging and how does it work?

John Anderson (JA): Normal human vision is limited to a very narrow, “visible” band of the entire electromagnetic spectrum. The infrared spectrum, also called thermal energy, has a longer wavelength than visible light. A thermal imager is essentially a thermal sensor capable of detecting tiny temperature differences in both hot and cold temperatures. Thermal imaging cameras allow anyone to see thermal energy (heat), which essentially gives the user superhuman eyesight. With thermal imaging, the part of the spectrum that we perceive is dramatically expanded so that we can “see” heat even without light.

Everything in the known universe emits, reflects or absorbs thermal radiation. A thermal imaging camera converts the “thermal data” it measures into visible images. Thermotechnology not only sees in the dark and detects invisible heat sources, but also helps the user see through fog and smoke. The image generated is known as a thermogram and is analyzed through the process of thermography.

RT: How can this technology be used by roofers?

YES: Thermal imaging is a popular non-destructive inspection technique used in construction. When a flat roof leaks, damage usually goes unnoticed as water seeps in and soaks the coverings and insulation over time. Rotting often develops, which can weaken the roof structure and later lead to expensive repairs. Given the difficulty of finding a water leak with the naked eye, thermal imaging cameras can help roofers locate water ingress, find moisture below the surface, and document drought with accuracy and safety. Because thermal imaging is much faster than visual inspection, inspectors can focus on the entire roof, not just the areas at risk. It also enables inspection at night and in the shadow area as no visible light is required.

RT: What are the limitations of pioneering infrared? How can you get the most accurate results?

YES: There are a number of factors that can affect the performance of thermal imagers and ultimately the outcome of an inspection:

• While a thermal imager can quickly identify potential moisture problems, it is recommended that you also use a moisture meter to confirm / verify the problem.
• Thermal cameras come in different resolutions, so different cameras have different limitations. With a lower resolution camera, the operator must get very close to a potential problem area in order to locate a problem, while a higher resolution camera provides more detail and clarity during an inspection. However, higher resolution cameras generally cost more than lower resolution cameras. Therefore, the operator has to consider which resolution is best for his needs, depending on when, where and how he wants to use the device.
• The heat values ​​can be influenced by internal heat sources or differences in the insulation thickness.
• The best time to scan a roof, often referred to as a “thermal window”, is when the roof is either warming up or cooling down, usually early in the morning and then just after sunset. Ideally, most roof inspections are carried out shortly after sunset during a cool down period to avoid shade and sun reflection problems on the roof during the day.

In addition, the best time to perform thermal imaging roof inspections is when there is a high contrast between the air temperature outside and inside the building. This makes it easier to spot potential anomalies. It’s also best to avoid inspections on windy days, as the associated wind and pressure changes can make it difficult to pinpoint problems. Meanwhile, overly sunny, warm days can create solar radiation effects on the roof that can mask problem areas.

RT: What types of infrared thermal products are best for roofers just starting out with this technology?

YES: While hand-held cameras have been used by roofers for years to locate water penetration, find moisture below the surface, and document drought, the job is time consuming and physical for roofers of all skill levels. Of the many types of handheld thermal imaging cameras, we recommend rugged devices that can handle the possible ingress of moisture and dust, as well as drips on hard surfaces. Additionally, contractors should use a thermal imaging camera with radiometric capabilities that will allow them to capture the temperature of every pixel in the scene so that the operator can better pinpoint specific problem areas for further inspection or repairs.

Many roof inspectors are now using unmanned aerial drones that are equipped with both thermal and visual cameras, as they can easily fly over large areas and provide a thorough view of the entire roof in just a few minutes. Range or dangerous areas. The inspectors may still have to go up on the roof and use traditional testing methods to further assess the problem. However, the total time compared to a thermal hand inspection alone is significantly reduced and potentially much safer because the drone pilot can safely keep his feet on the ground.

RT: What training or regulations are required to operate these devices?

YES: Laws and regulations governing who can make recommendations for roof damage vary from state to state. When using a drone equipped with a thermal imaging camera, operators should be familiar with local requirements and always work with a licensed professional to ensure the scans have real, actionable value. In addition, there is a national standard that defines the methodology by which thermographers using handheld cameras to inspect roofs should be used. ASTM c1153-10 (2015) Standard Practice for Locating Wet Insulation in Roof Systems with Infrared Imaging also applies to drone operators.

FLIR also works with the Infrared Training Center (ITC) to offer certification courses that teach best practices and techniques. It is important that roofers understand how the camera “sees” different roofing materials and learn techniques to know when, for example, a “cool” point in the scene is just cool air or water under the roofing membrane. It is important to know how each layer in the roof system affects the thermal patterns. The user needs to understand the assembly of the roof so that he can understand whether what he is seeing is a problem or just part of the structure.

RT: What is the lifespan of a typical thermal device if it is used and cared for properly?

YES: There are several factors that affect the life of a thermal imaging camera. For roof applications, a robust camera is required that can cope with the environmental influences present on a roof such as high heat or bitter cold as well as drops on hard surfaces or from one floor to the next.

Many thermal imaging cameras are equipped with a rechargeable lithium-ion battery. Therefore, cameramen must ensure that the device and its batteries are not exposed to excessive heat (e.g. on the dashboard of a truck in mid or summer) or left out in freezing temperatures – all factors that can significantly affect the performance of the battery and thus the service life of the camera. A roof inspection device can last for many years if properly cared for.

RT: What software is needed and how can contractors access the information collected by the camera?

YES: No software is required to use a device, but it is a recommended add-on for editing images and generating comprehensive inspection reports. Users have several options for software: there are free versions that provide basic image manipulation and rapid reporting, and paid versions that offer advanced measurement and image analysis, as well as editing and custom reporting.

Depending on the software, operators can adjust colors, apply spot meters, isolate specific points within a scene for further review, or edit an image in post-processing to better interpret a scene to be included in a review report. For extensive roof inspections, FLIR offers a paid software option that allows customers to batch edit large numbers of images, saving a lot of time.

Thermal image of the building with the metal roof half installed

RT: What variables on the forward-looking infrared devices themselves should contractors be aware of?

YES: For roof applications, there is a national standard that defines the methodology by which thermographs using handheld cameras to inspect roofs should be used (ASTM c1153-10 (2015)).

As for the device itself, there are some good rules of thumb that roofers should keep in mind when considering a portable thermal imaging camera. These include:

• A radiometric thermal imaging camera, ie the camera can detect and measure the temperature of every pixel in the field of view of the respective camera
• A camera rated IP65 or higher – a camera that is dustproof and works in rain or snow
• A camera that can be used to take and record both photos and videos for post-processing or review, and a camera that offers additional software features such as multiple spot temperature gauges, including the ability to adjust temperature gain within a range
• One with an ergonomic pistol trigger that makes it easy to operate a camera with one hand, compared to a touchscreen device that often requires two hands to operate. Sometimes these can be difficult or impossible to use with heavy gloves.

Via FLIR systems

FLIR Systems was founded in Tigard, Oregon in 1978 to drive the development of high-performance, low-cost infrared (thermal) imaging systems. However, the company’s history goes back further to the 1950s when Agema of Sweden (later bought by FLIR in 1998) developed the first commercial thermal imaging cameras, mainly for inspecting energy infrastructure. These first thermal imaging cameras were so big and heavy that they were mounted on the back of a car or truck.

Today, FLIR offers a diversified portfolio that covers a range of government and defense, industrial and commercial applications. With major advances in the size, weight, performance, and cost of thermal imaging cameras, FLIR thermal imaging cameras can be used in cell phones to large gimbals in military or search and rescue aircraft. More information is available at www.flir.com. RT

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