Infrared (IR) Thermography and the Home Inspection

Infrared (IR) cameras can be used to find anomalies that may otherwise remain hidden in walls, floors and ceilings. Infrared energy is heat energy. Since all objects are above absolute zero (-273° C), they emit heat energy to varying degrees, even ice cubes! A properly trained infrared thermographer can interpret an infrared image and determine if roof or plumbing leaks exist, if there is missing insulation in a wall, if an electrical component is reaching critical temperature levels, or if no major issues exist at all. The purpose of most thermography work, as performed by home inspectors, relates to looking for anomalies. An anomaly is a situation that is otherwise not to be expected under normal conditions.

Heat is energy and is continually moving to an object or surface with less heat. Once two nearby objects are at the exact same temperature, there will be no further heat transfer between these two objects. Also, there is no such thing as 'cold'. Cold is really a relative term meaning simply a lower amount of heat energy compared to a warmer object. For infrared technology to work properly, objects must be at different temperatures. If you were to walk into a room where everything was the same temperature, IR technology wouldn't be of much use. Luckily, in homes and other buildings there are various components such as walls, ceilings, plumbing, electrical wiring, heating/cooling equipment, insulation, etc. Each of these systems and components relate with heat energy in some way and how well these systems deal with heat energy is where infrared technology comes in.

Side-by-side images (visual vs infrared) showing a coffee cup.
Notice the coffee cup is half-full of hot water.

Moisture within a building can damage building components and can lead to rot and/or mold. Quick moisture detection is key to minimizing potential damage and repair costs. An IR camera can see the heat transfer characteristics common with moisture and helps show what is wet or damp and what is dry. The IR camera does not actually "see" the moisture but does detect the cooling effect of moisture evaporation.

How does Thermography work?

Thermography is defined as obtaining and analyzing thermal information using a non-contact thermal imaging device. An infrared camera does not measure temperature. Instead, it measures heat energy. Infrared technology doesn't see through walls and isn't X-ray vision nor night vision, but instead allows the user to examine the heat transfer characteristics of the objects around us. Thermal imaging can work in complete visual darkness since the visual light spectrum (what we can see with our eyes) and infrared spectrum are in different wavelengths (approx. 0.4 to 0.75 micrometers for visual energy vs. 1 to 1000 micrometers for infrared energy). The type of IR cameras that most thermographers use measure IR energy in the 8~12 micrometer "long-wave" wavelength range.

Using an infrared camera, warmer objects are typically lighter in color (red, orange, yellow, or white). Cooler objects are typically darker in color (blue, purple). To an untrained eye, a bunch of odd patterns, shapes, and colors on the infrared camera's screen can easily be confusing or misdiagnosed. Issues such as cold air entry may look similar to missing insulation or the issue may be completed missed. To the properly trained infrared thermographer, however, these anomalies can be properly identified. Once a potential issue is found, it is wise to confirm the issue with other tools (such as a moisture meter if signs of water/moisture are apparent).

These are side-by-side images (visual vs infrared) of an electrical outlet in an older home.
Notice the cool air coming in at base of outlet cover plate. Sealing the outlet against air infiltration is an inexpensive and cost saving exercise to prevent heat loss.

If properly done, a thermal image can also be "thermally tuned" to highlight the issue(s) of concern within the image and to maximize thermal contrast in the image or to 'filter' out heat transfer above or below a set temperature.

Some Infrared Thermography Applications within a home inspection:

Missing or displaced insulation - seeing heat transfer into or out of a building can help determine if there is missing or displaced insulation in walls or ceilings.

These are side-by-side images (visual vs infrared) of a wall/ceiling junction in a home.
The above IR image indicates missing insulation. The temperature in the attic of home is WARM compared to the cooler house interior.

Roof Leaks - evaporation occurs when a building material gets wet which creates a cooling effect that can be seen with an IR camera.

These are side-by-side images (visual vs infrared) of an active roof leak within interior of home.
The above photos show a small roof leak that has changed the surface temperature of the ceiling - no visual indication was found.
This small roof leak happened to coincide with an area of roof with damaged composition shingles.

Overheated Electrical Components- when electrical components (wires, circuit breakers, switches, etc.) are energized with electrical energy, they heat up. This is to be expected, however if components heat up well beyond their design criteria, this may indicate a faulty component or a loose connection; either situation may also lead to a fire in some circumstances.

The above IR image illustrates the heat energy given off of by energized wiring (visual vs infrared).
This is a normal occurrence when wiring is energized (powered), however a properly trained IR thermographer can analyze what is considered normal
versus what may be considered excessive heating of wiring or a thermal gradient.

Pete Sutch, owner/inspector of WIN Home Inspection Olympia, is a Certified Level 3 Infrared Thermographer and an ASHI Certified Inspector. He can be reached at: (360) 709-0221 or psutch@wini.com