What is Thermography (Infrared Vision, Night Vision)

Most of us old enough are familiar with the movie Predator (1987), where Aliens use futuristic gadgets including infrared vision to hunt down and kill big game creatures from all over the universe (including humans on Earth). In the movie, the aliens use infrared vision to see through smoke, foilage, walls and the cover of night to hunt down and eliminate their human targets.

In real life, infrared technology has been around for over 50 years and was originally developed for military applications. Infrared thermographic imaging allows for detection of an otherwise invisible spectrum of light radiation, allowing for vision in many scenarios where the naked eye is effectively blind.

In the movie Predator (1987) aliens use infrared imaging as well as other futuristic gadgets to hunt down their prey. It may come as a surprise to some that this futuristic technology (thermographic imaging) is now used in much more mundane applications including construction and manufacturing inspections.

In the last decade the declining cost and increasing availability of infrared thermographic cameras has driven an increased demand for these devices in civilian applications. Aside from medical uses, infrared cameras are growing in popularity as a tool for manufacturing and construction inspections (including SPF foam roofing). Infrared cameras can speed up inspections and make them more thorough since enhanced detection allows inspectors to see flaws which are invisible to the naked eye.

Thermography Background

Around 1800 the royal astronomer Sir William Herschel discovered dark heat radiation. Subsequent discoveries allowed Samuel Pierpont Langley to develop the bolometer in 1880, the first infrared detection camera. Early reports indicated the bolometer could detect a cow at 400 meters at night. The technology effectively detected infrared radiation, beyond the spectrum of visible light and displayed heat differentials with varying colors.

Early advances in thermographic technology applications were driven by research and development for military and security applications. The most obvious value for military use is that heavy military equipment and engines (for example jet propulsion) provide a massive heat source, and due to high inefficiencies these heat sources can easily be detected.

Thermography Looks Beyond the Visible Light Spectrum

A FLIR (Forward Looking Infrared) also known as infrared (thermographic) camera, is a tool that forms an image using infrared radiation. In many ways, a picture is formed, similar to a common camera which creates an image using our visible spectrum of light. However, a thermographic camera can view wavelengths as long as 14,000 nm (14 µm); far beyond that of visible light.

military flir
The heat radiation created by the burst of these heavy artillery cannons is displayed by this thermographic image. Dark Radiation is more abundant around a major heat source, and although it is invisible to the naked eye, a thermographic camera can detect it (as demonstrated by this image).

In contrast, a common camera only detects light in the 450–750 nanometer range. It is important to note that the colors displayed by a thermographic camera are simply a symbolic display of temperature differentials–which are beyond our visible spectrum of light. In other words, the image is a color representation of temperature differentials (the actual ‘colors’ do not exist in our visual spectrum).

Thermographic Applications (Infrared Cameras)

In the late 1950s the US military began to implement thermography in military applications. Some of the early uses included heat seeking missile targeting systems and FLIR (Thermal Forward-Looking Infrared) which were used in applications such as night vision. Two decades later, some medical applications were discovered for thermography.

During the 1970s it was discovered that infrared images could provide early detection of breast cancer. Although the USA has shifted to x-ray and ultrasound mammograms, much of Europe, including France and Germany still use thermography for early detection of breast cancer. At the turn of the century thermographic cameras became more widespread and the cost to purchase these devices began to decline.

Expanding Uses of Thermographic Cameras

Today, infrared cameras are often used in many new applications including scientific research, construction, and facilities management (in additional to medical and military uses). FLIR (Thermal Forward-Looking Infrared) cameras construction applications range from building diagnostics, energy auditing, home inspections, and property management to HVAC, plumbing and restoration.

Even fire fighters have started using thermal imaging to assess fire damage through smoke, fog or many other situations where normal vision is obscured. About a decade ago, no fire departments could reasonably afford thermal imaging. However, mass production has substantially reduced the cost, making infrared cameras a new standard for firefighters, which has saved many lives.

One of the newest areas of infrared technology applications involves uses with construction, such as sprayed polyurethane foam (SPF) roofing and insulation systems.

home flir image
Infrared home inspection is increasing in popularity due to the enhanced detection FLIR imaging provides (which is superior to the an inspection limited to the naked eye).

Cost of Thermographic Cameras and Infrared Inspections

Through infrared technology, formerly invisible problems can now be detected quickly by non-obtrusive means at a reasonable cost. Currently Infrared cameras are available starting around $2,500 and up. However, the types of cameras used for building inspections may often cost $10,000 or more. Based on price, quality factors such as display size, weight and infrared detection methods vary. Cooled infrared detectors are usually heavier and more expensive.

Un-Cooled vs Cooled Thermographic Cameras

Some benefits of cooled infrared cameras are the highest image quality available as well as a the use of higher F-number lenses (making high performance focal lenses both cheaper and more compact for cooled detectors). Un-cooled infrared cameras are smaller, and more lightweight and often more convenient to use for inspection purposes. Either type of infrared camera provides a powerful diagnostic tool for detecting many types of potential building envelope problems.

Infrared Imaging Provides Enhanced Construction Inspections

Effectively, an infrared camera can detect problems via non-obtrusive means, which are completely invisible to the naked eye. Some examples of issues which a FLIR camera may detect are walls missing insulation, as well as air leaks around doors and windows. Some recent camera models are even capable of making raw R-Value estimates of surfaces.

A traditional building inspection relies primarily on visual clues to problems under the surface which sometimes allowing buildings with construction problems to pass with a good bill of health (due to lack of obvious issues). An extremely thorough inspection often requires destructive means to determine the problem. On the other hand, many of these problems can be detected through infrared thermography.

Facilities managers for example, can see problems with machinery or engines long before heavy vibrations, overheating or complete meltdown occur. Preventative maintenance can be scheduled instead of costly repairs. Most third party infrared camera building inspections cost somewhere between $350 and $500 depending on locale, equipment used, and the square footage of the area to be inspected.

missing insulation flir
Infrared cameras allow for a superior inspection. For example, the infrared image on the left clearly shows missing insulation (left image). A normal inspection, limited to the naked eye, (image on the right), detects no flaw(s).

Infraspection Institute: Infrared Thermography Certifications

In North America, the Infraspection Institute certifies a few varying levels of thermographers. For example, level one only takes a day or two of schooling, while level 2 only takes about four days of instruction. Both certification levels require months or years of field experience in conjunction with passing tests. Presently, there are about 1,000 certified thermographers around the world, indicating not that these people know everything there is to know, but that they have passed an exam and they do know a certain amount. There are also some self-certifications available to companies. However, the quality of this type of certification may be suspect since they are provided by the same company offering the inspection.

What Thermographic Imaging Can Detect

Often the best candidates for insulation inspections are buildings with excessive heating or cooling bills, 15 years or more of age, or obvious drafts. Some examples of issues which thermographic cameras can detect are:

  • Air Infiltration
  • Moisture Infiltration
  • Exfiltration
  • Plumbing Leaks
  • Major Temperature Differentials
  • Missing Insulation
  • Leak Detection
  • Electrical Issues

An infrared camera inspection can detect any of these problems without the destructive means of a traditional inspection, and as already mentioned, infrared thermography can also find these issues without any surface clues (which a traditional inspection relies on).

Infrared Cameras in Roofing Applications

Thermographic imaging can quickly reveal any weaknesses on an SPF foam roof. An inspection with a FLIR camera can reveal problems with insulation, air leakage, moisture (mold), electrical, heating and cooling problems, as well construction defects. Generally, a roof owner must rely on a visual inspection for obvious surface problems, as well as an internal leak inspection to determine where and what problems are. Usually, the entire roof ends up being replaced since neither the owner or the roofer can pinpoint the problem areas. Thermographic camera imaging provides an alternative that doesn’t just show where leaks are; it shows exactly where moisture has built up. This is especially helpful with flat and BUR (built up roofs) roofing.

Thermographic Imaging Detects Moisture and Leaks

Generally, a leak can be located by indentifying areas where insulation has absorbed moisture. Preventative repairs can prevent future disaster since moisture can spread throughout a roof over the course of just 1-2 years, resulting in an entire roof which must be replaced. In the case of a large building, this can mean the difference between a $500 repair and a $100,000 roof replacement.

Thermography for Estimating Future Roof Life

Thermographic cameras are also useful for estimating how much life a roof has left. In the USA, the average roof lifespan is a mere 8 years. This lifespan can be extended by pinpointing problems and correcting them with early preventative repairs, instead of simply reacting with a full roof replacement, after a disaster. The costs of roof replacement with traditional bur roofing continue to rise along with the cost of oil (since tar or asphalt is an oil based product). Schools, business, and government entities have already started realizing that old patterns of behavior cannot be maintained without substantial increased costs.

Thermographic Inspections are Becoming the New Roof Inspection Standard

This has also led to an increase in the popularity of SPF Polyurethane Foam Roofing, and other flat or low slope roofing alternatives (to traditional BUR and EPDM roofing). The new modus operandi which many institutions are adopting is to accurately identify roof problems with infrared, then make targeted repairs, extending the roof life as much as 10 or 20 years. The old way of tearing things apart and guessing is quickly becoming history.

For example, The Army Corps Of Engineers now scans army roofs with infrared every few years, indentifying potential problems years before they result in leaks, preventing disaster and extending the life of their roofs.

Improved Thermographic Technology Further Increases Usability

The latest equipment is also more accurate and can even show degrees or exact temperatures of any given surface. Another benefit to keep in mind, is that infrared scanning of roofs is non-destructive and does not interrupt work schedules or disturb building occupants. Generally, the cost of an infrared inspection ranges from $1,000 to $5,000. Normally, the cost of an infrared roof inspection breaks down to just 1 to 7 cents per square foot.

An infrared roof inspection is substantially more cost effective and environmentally friendly than completely replacing a rooftop at $3 to $12 per square foot (consider the oil used in asphalt, or the landfill waste which is created by tearing off an old roof). Also, keep in mind that old roofs often contain hazardous materials such as asbestos–where less removed is better.

If you have trouble finding a local certified thermographer, there are some resources and directories out there. For example, The “Directory of Infrared Thermographers” can help building owners find certified local thermographers.

Infrared and Polyurethane Foam Roofing and Insulation (SPF)

Presently, the use of infrared thermography is not widespread in the foam roofing and foam insulation industry. However, we have reason to believe this will soon change and that industry standards will develop specifically for inspecting both foam roofing and SPF insulation with FLIR type cameras. There is great potential in the area of infrared camera inspection and many benefits such as moisture detection and air infiltration are just a few of many.

Infrared cameras could even provide a valuable pre-inspection tool, to determine whether an underlying roof substrate is fit to remain on a building, or whether it must be torn off before a polyurethane foam roof may be installed. Infrared camera inspections could also verify the quality of completed projects including polyurethane foam roofs or SPF insulation. This could help preemptively correct any installation problems which would normally be invisible to the naked eye.

The Future of SPF Roofing and Thermography

While the SPF industry does not have any current standards requiring thermographic inspections, we do expect this to change in the future. As the prices and quality of infrared cameras continue to improve, we expect both the prevalence and use of these devices to continue to help building owners find new ways to cut maintenance costs and make more targeted corrections to construction problems.


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– Infrared thermography in the quality assurance of manufacturing systems. By: Meola, C.; Giorleo, G.; Nele, L.; Squillace, A.; Carlomagno, G. M.. Nondestructive Testing & Evaluation, Jun2002, Vol. 18 Issue 2, p83-90, 8p
– INFRARED THERMOGRAPHY AND GROUND PENETRATING RADAR FOR AIRPORT PAVEMENTS ASSESSMENT. By: Moropoulou, A.; Avdelidis, N.P.; Koui, M.; Aggelopoulos, A.; Karmisb, P.. Nondestructive Testing & Evaluation, Mar2002, Vol. 18 Issue 1, p37, 6p
– Use of an infrared camera for nondestructive quality inspection of fiber-optic components. By: Zaitsev, O.; Kalinushkin, V.; Lobachev, V.; Yuryev, V.. Instruments & Experimental Techniques, Nov2008, Vol. 51 Issue 6, p898-901, 4p, 2 diagrams, 3 bw
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4 thoughts on “Infrared Cameras: Roofing and SPF Applications”

  1. Hey, predator was a great movie. It’s a good thing you mentioned that. Seriously, it is funny that a military technology has been adapted for home use. What will they think of next?

  2. It’s almost amusing that military technology like infrared has become something to improve the living standard of the general public–by making home inspections & repairs more effective. If facilities managers can lower the cost of running manufacturing or inspecting manufactured items (with infrared) these savings will eventually get passed on to the public. While I’m not a fan of excessive military spending, I think it’s great that war technology can actually be something everyday civilians can benefit from-in a non-war related setting.

  3. I have a customer looking for something to spray on the roof of his church and when it rains they can go into the loft and use a uv light to detect the dye leaking thru the roof somewhere, but it cant stain the roof, walls or ground

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