A few years ago it seemed like something out of science fiction, but now roofing contractors around the country are routinely using cameras that detect infrared (IR) radiation to conduct roof inspections and pinpoint roof leaks.
To get an overview of the benefits of today’s IR technology, Roofing Contractor spoke with Ron Lucier of FLIR Systems Inc. (www.goinfrared.com), which designs, manufactures and markets infrared imaging systems worldwide for a variety of thermography and imaging applications. Lucier is the Regional Thermography Course Manager at FLIR’s Infrared Training Center (ITC) in North Billerica, Mass., and he teaches courses on IR thermogrpahy at the main center and all over the country.
According to Lucier, thermal or infrared energy is light that is not visible because its wavelength is too long to be detected by the human eye. It is the part of the electromagnetic spectrum that is perceived as heat. Thermography, or thermal imaging, refers to the process of recording the emission of thermal or infrared radiation by employing the use of a thermal imaging device or infrared camera.
An infrared camera detects infrared energy and converts it into an electronic signal, which is then processed to produce a thermal image on a video monitor and perform temperature calculations. “Infrared cameras use sensors called bolometers,” said Lucier. “They look at one part of the spectrum we can’t see, infrared, and convert the information into a picture we can see.”
A common misconception is that people looking at an image think they are seeing temperature readings, noted Lucier, but they’re really seeing a representation of the thermal radiation on the surface.
“In roofing, there are many potential false indications, so training is the key,” he said. “To get the maximum out of the technology, you really have to understand the science.”
The roof course at ITC is a two-day course, and participants actually inspect an EPDM roof at the plant as part of the training. They also examine images from actual roof inspections depicting different types of problems.
With an infrared camera, roofing contractors can convey their expertise to building owners and document roof conditions, noted Lucier. “Once we add this to the contractor’s expertise, we have a very powerful weapon,” he said.
For a roofing contractor, the most obvious benefit of an IR camera is its ability to detect moisture a roof system.
“When water gets caught in a roofing system, we count on the sun to help us detect it,” said Lucier. “It all depends on the concept of heat capacity, also known as specific heat. Water heats up more slowly than most substances and holds heat longer, he noted. “The sun heats up the roof, but the water heats more slowly that the dry roofing material,” he said. “The water also cools off slower than the roof, so we can check it at night. That’s where we get our classic thermal patterns.”
There are many ways contractors can benefit by adding an infrared camera to their arsenal of tools, according to Lucier. “The three most obvious ones are to maintain quality control, to find leaks, and to find areas of wet insulation.”
1. Quality control. “Foremost is quality control,” he said. “The contractor can go up on a roof right after the roofing job has been completed to ensure that no water has gotten into the roof system during construction. Contractors can also check for bad seams to eliminate callbacks.” The completed job can be documented with digital photography, video recording and infrared imagery. “If I were a contractor, I would use a digital video recorder to record the as-left condition of the roof,” he said.
2. Finding leaks. “If a leak has developed, this can help you pinpoint where it’s occurring,” said Lucier. “In a newly installed roof, leaks can be hard to track.” He recounted a case in point - a museum building he was called in to examine. “The interior leak was 106 feet from the outside intrusion point. The water was running along the channels of the deck. Based on the laws of physics, sometimes water isn’t readily absorbed by polyiso. It might be easy to find roof moisture, but it’s often hard to find the source of the leak.”
Infrared cameras can have their limitations as far as leak detection goes, Lucier cautioned. “The IR camera finds moisture, but it doesn’t necessarily find the leak,” he said. “Typically it will be in the general area and the camera will get you pretty close, but experience can help.”
3. Finding wet insulation. Wet insulation is easy to spot with IR technology, and a roof survey can pinpoint the areas that need to be replaced. “As roofing contractors know, wet insulation increases heating and cooling costs and degrades roof materials,” he said.
There are several features to keep in mind when evaluating an infrared camera, according to Lucier. He noted a few, including:
• Size and portability: “Some models come with a holster, and some roofs are only accessible through a roof hatch or ladder, so portability is a key consideration,” said Lucier.
• Resolution: “Most roofing problems are gross,” said Lucier. “For really small leaks, though, high resolution imagery can be key.”
• Size of the display: “The size of the display you’re looking at can make a big difference,” he said.
• Digital capabilities: Some units incorporate a digital camera and video capabilities, said Lucier. “With the FLIR T Series, the IR image and the digital image are aligned. You can rotate the visuals to precisely identify the location of problem areas.” This can eliminate the need to physically mark problem areas, a process that can be problematic with some systems.
Roof Inspections
Lucier recommends that contractors conduct a thorough visual inspection of the roof before breaking out the IR camera. “There are advantages to doing a walkover first, and most of them have to do with safety. You can check for rotting sections of deck, holes or other safety hazards.” As clear visibility is essential, Lucier recommends doing the visual inspection before nightfall. “It allows you to focus on the housekeeping on the actual roof. If you see poor housekeeping, you are likely to see a lot of damage.”
The IR camera can then used after the roof cools down, and most inspections are conducted at night. But not all IR inspections must be conducted in the dark, notes Lucier. “It it’s a sunny day and cools off quickly, you can conduct a roof inspection before sundown,” he noted.
It’s essential to gauge the weather when deciding when to conduct an inspection. “If it’s overcast, or there won’t be a large temperature drop at night, you might have to wait,” he said.
ASTM 1153 details the guidelines for inspections, stated Lucier, and contractors should familiarize themselves with its contents. He offered some tips for contactors conducting IR roof inspections.
“Start as high up as you can,” he recommends. “Use an elevator shaft, a penthouse, or a neighboring building if you can.”
Proceed section by section, using best safety practices. “Inspections should involve at least three people, with one person solely dedicated to making sure the other two follow proper safety precautions,” he said.
With ballasted roofs, care is essential, as the images can be tricky. “Once you see some hot spots, check to make sure that you don’t just have a big pile of rocks,” he said. “It’s an urban legend that you cannot inspect heavily ballasted roofs with infrared. You can. I have the video to prove it.”
In cases where the thermographer thinks there is water in the system, other technologies can help document the conditions. Spot checks with a capacitance meter, penetrating moisture probe, or core cuts can help determine the extent of the damage. “It’s nice to confirm with other sources if you can,” he said.
Of course, there’s always the option of taking to the sky to get the perfect overall view. Aerial inspections have their benefits and their limitations, noted Lucier. “You have to have a high-resolution camera,” he said. “It’s great to get a broad overview, but it’s always helpful to be up on the roof. If you have the opportunity, a walkover and an aerial inspection can work very well together.”
ASTM 1153 doesn’t address walking under the roof during the day, but this type of inspection can also provide helpful information, according to Lucier. “The same physics that mean water can be hot at night mean water can be cool during the day. In areas where there are no shadows, you can pinpoint water during the day.”
Follow ASTM and OSHA guidelines and use proper fall protection, urged Lucier. “We teach, ‘Always walk forwards; never walk back wards,’” he said. The third member of the crew should be solely dedicated to safety and on the lookout for problems, and everyone should have the necessary safety training. “If you don’t understand the OSHA standards, you shouldn’t be on the roof,” he said. “We go over the regulations in our training.”
IR thermography can be used in residential as well as commercial applications, noted Lucier. “It does work on fiberglass and asphalt shingles as well,” he said. “The market is expanding.”
Understanding physics and the keeping track of the weather are the keys to setting up inspections, said Lucier. “You have to use the environmental conditions to make your decisions,” he said. “Once you understand the science of IR thermography, the applications get easier. That’s when the thermographer can really get a chance to shine.”
Sidebar: Ongoing Education on Infrared Cameras
FLIR Systems Inc. provides training courses at the company’s Infrared Training Center (ITC) in North Billerica, Mass., and at venues across the country, including the InfraMation infrared applications conference. Roofing Contractor sat in on a roofing applications clinic conducted by Tom Coffey, a thermography course instructor at the ITC.Coffey began with a word of caution for IR consultants who are not experts on roof systems. “One of the most powerful applications of this technology is detecting moisture, but remember, you’re not a leak detector. If you take your camera and have proper training, you can find indications of roof moisture. The actual leak may be very difficult to locate. Do not over-represent yourself - you are not a leak locater.”
Coffey walked attendees through various types of low-slope and steep slope roof systems and pointed out potential difficulties in performing various types of IR inspections, including walkover, walk-under and flyover methods. “The tendency is to think all roofs are clean of equipment and easy to inspect,” he said. “Unfortunately, that is rarely the case.” Conduits, pipes, exhaust vents, HVAC equipment and drains can limit the area that can be inspected, noted Coffey, who urged that all housekeeping problems be documented with photographs. Inspections cannot be conducted while ponded water is present, but any standing water should be documented with photos, he suggested.
The type of insulation is important, said Coffey, who showed attendees a series of images from actual inspections to illustrate typical problems. “Insulation that has a high ability to absorb water - closed cell - will stay wet for a very long time,” he said. “Insulation that drains freely may yield a thermal indication for only a few hours after precipitation. Sometimes you have to get here pretty quickly.”
He also walked attendees through ASTM C1153, the recommended standard for commercial roofing inspections with an infrared camera. It can be purchased online at www.astm.org. The standard outlines equipment parameters, roof types, and environmental conditions. “The standard is an excellent source of general requirements,” said Coffey. “However, C1153 states that inspections can be conducted starting one hour after sunset. This is not always correct. The best images may not be obtained for three or four hours after sunset. Check the roof for early indications starting one hour after sunset.”
Safety procedures cannot be emphasized enough, according to Coffey. He recommends a minimum of two people on the roof, preferably three or more, and only after the underside of the roof has been inspected for structural integrity. “Avoid stepping on blisters that are common on built-up and gravel roofs,” he advised. “Have a cell phone or radio available in case of emergency, and notify the police that you are inspecting the roof at night.”
He urged all contractors to be aware of all OSHA regulations, including 29 CFR 1926.501, which sets forth requirements for employers to provide fall protection systems.
“If you have an accident, you will meet an OSHA inspector,” he said.
For more information, visitwww.goinfrared.com.
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