Thermal imaging is a non-invasive inspection process that detects temperature variances in building components. In home inspections, one of the biggest areas of thermal concern is insulation. Thermal images can reveal missing insulation and “cold spots” where heat isn’t being maintained—problems which can lead to energy loss and increased energy costs.
In a typical thermal image of a house with proper attic insulation levels, you’ll see a continuous line or pattern along the edges of all rooflines, walls, windows, doors and other surfaces. This indicates even temperatures across these surfaces. If there’s no line running across these areas, it means there are isolated pockets of higher or lower temperatures that need to be evaluated further for possible cause before moving on.
During home inspections, thermal imaging cameras are used to find issues like the following:
- Missing insulation in walls, attics and crawlspaces.
- Blistering or bubbling of paint on rafters, chimneys and exposed foundation.
- Insulated pipes exposed to outside air temperature.
- Cold spots where heat isn’t being maintained.
- Issues with the home’s HVAC system that may be causing a problem with a specific room or area of the house.
Levels of radon gas that need further evaluation before moving forward with a purchase—radon is often associated with missing basement insulation and higher exterior temperatures around the foundation.
Excess moisture in basements from water seepage or chronic ground water problems.
Common areas where rodents, bats and birds gain access to the building structure.
Active leaks in rooflines, attics and around chimneys that allow air infiltration into the home’s attic or ceiling cavity.
Cold spots where heat isn’t being maintained (often due to poor insulation levels).
Improperly working forced-air heating systems that need repair or replacement before moving forward with a purchase—the HVAC system may not be blowing cold air into just one room or area of the house, but rather not at all in certain parts of it.
Excessive moisture from plumbing leaks inside walls and ceilings, possibly caused by a broken pipe or other problem in a nearby area.
Insulation problems can lead to a number of problems. For example, moisture can enter a wall cavity if insulation levels are too low and condensation forms on the inside walls as a result. This may lead to mold growth and wood rot from constant exposure to high humidity levels.
Inspectors use thermal imaging cameras not only for identifying issues like these, but also during the energy compliance portion of home inspections as well as insurance-related claims investigations.
The benefits of using thermal imaging in home inspections
Thermal imaging cameras show temperature variances that aren’t visible to the human eye. They reveal thermal inconsistencies or issues that may be difficult for a home inspector to see with the naked eye, and they’re helpful in identifying problems like:
Cold spots where heat isn’t being maintained
- Missing insulation
- HVAC system concerns (including those related to safety)
- Moisture problems inside walls and ceilings
- Building envelope leaks (such as those around chimneys or rooflines)
- Excessive moisture coming from plumbing fixtures such as sinks and toilets (indicating a possible problem with the plumbing vent piping system)
Excessively high outdoor temperatures around exterior foundation vents, which can indicate hidden moisture problems. This is typically seen in areas around the home where moisture problems are hidden, especially if the building materials used to construct the basement or crawlspace floor allow for air circulation between them and the soil below.
While thermal imaging cameras can’t diagnose an issue, they do show things that should be evaluated further during a home inspection. Understanding what’s normal versus what isn’t can help provide additional information about an area of concern, which may indicate how serious it is and whether it needs immediate attention before moving forward with a purchase.
Additionally, insurance companies often request use of thermal imaging cameras when investigating claims related to water damage (or other issues). They’re used not only to identify problem areas, but also to show potential sources of involved in causing a claim—such as taking pictures of cold spots in insulation that indicate missing or insufficient levels.
How to read a thermal image
Thermal imaging cameras show not only the thermal characteristics of what’s being viewed, but also reveal its potential energy efficiency concerns. Understanding how to read one can help you identify problems with your home more easily and quickly than using the naked eye alone.
For example, an HVAC system that isn’t properly working will cause hot spots over each heat exchanger (typically the outdoor unit) that indicate lack of airflow—which typically indicates a blower motor or capacitor issue. Cold spots near these units can mean improperly insulated areas around them, which means higher utility bills as the homeowner tries to make up for this loss of efficiency by running their heating system longer or at higher settings.
Tracking cold spots throughout a house during wintertime (when exposure to colder temperatures is most common) can help a home inspector identify problem areas that require additional insulation. In some cases, this can be as simple as adding a thick layer of fiberglass batts under a raised wood floor or in the wall cavities of older homes with less-than-ideal insulation levels. Homeowners looking to reduce their energy costs may benefit from inspecting these areas and determining whether they need more insulation installed after reviewing the results of thermal imaging photos taken at various times throughout the year.
Many HVAC system problems can be detected by home inspectors using thermal imaging cameras—especially those related to inadequate airflow or lack thereof. For example, if you have cold spots near an outdoor unit with its fan running, it’s probably not working properly and may require you to call a technician for service.
Other areas of concern that can’t be seen with the naked eye include:
- Moisture problems around windows and other building envelope elements (indicating potential for energy efficiency issues)
Missing insulation (which could cause hot and cold spots, depending on whether there’s adequate coverage). While the U.S. Department of Energy says about 30 percent of homes have insufficient insulation, unfortunately it can be difficult to determine this without using a thermal imaging camera or other diagnostic tools such as gas measurements, air leakage tests or professional inspections. Cold spots caused by improper work during construction —such as closing up rooflines without adding wall insulation—can lead to increased cooling costs during summer months, as well as drafts from outside.
Inadequate attic insulation levels (which can cause ice dams during winter months, depending on whether there’s a vapor barrier installed). And while moisture around chimneys isn’t abnormal when it’s cold outside and warm inside, significant amounts of condensation—or “sweating” bricks—can indicate that this area isn’t properly vented or insulated. As a result, you may need to add a chimney blanket to reduce heat loss through this aperture in the roofline.
Additional top cover insulation is important in many areas of North America because typical building materials aren’t energy efficient enough to reduce your heating bills during the winter months below average local temperature ranges. In colder climates where homes are heated year-round, home inspectors may also find that poorly insulated walls or ceilings contribute to hot spots. This can be due to insufficient vapor barriers in exterior wall cavities or because the insulation itself is air-permeable, which allows warm humidity inside your home to escape outside through these openings.
While not every cold spot you see during a thermal imaging inspection indicates an HVAC problem, it does become more likely as you document these issues throughout various parts of your home. At this point, focusing on these areas can help you prioritize repairs and add insulation where it’s most efficient—instead of wasting money sealing off drafts from rooms that don’t need them. In addition to inspections before placing a property on the market for sale , thermal imaging cameras have increasingly been used during home inspections in an effort to help buyers understand what they’re getting into.
Depending on the severity of problems you find, it may also be possible to add insulation or repair some HVAC systems yourself (rather than paying a professional).