Pictured below are some examples of conditions that a thermal scan could reveal.
The first two are of a wall space missing insulation above the windows. When outdoor & indoor temperatures have enough of a difference then this type of deficiency really shows up. You can also see where the corners that are colder than the main areas of the walls also stand out in their color difference. Commonly corners will have insulation missing and possibly some air infiltration.
Thermal images can be presented in different color palettes and my preferred is called Lava. (White hot to yellow, orange, red in the middle, then from violet cooling off through shades of blue to the coldest at black.)
After a new home builder discovered the bathtub/shower valve had the hot & cold water reversed, the plumber did some repairs. The drywall was patched and they were finished. But wait! The thermal imager scan reveals temperature anomalies in carpeting and drywall. In the closet adjacent to the tub, these materials were wet days after the repairs and if left unattended for any longer there would have been more water & issues developing in major and far reaching ways! Mold, mildew, wood rot, and perfect conditions for wood destroying insects.
The leaky plumbing fixed, walls repaired again, carpet dry and house was healthy when new homeowners move in!
These pictures show; #1 Wet drywall in a closet coming from a bathtub on the other side of the wall. #2 Front door with air leaking through due to poor weather stripping. #3 HVAC ductwork at the plenum connection is not properly sealed. #4 Ceiling contains moisture due to condensation leaking from the attic evaporator unit above the chandelier.
What is Infrared Thermography and how do I use it?
Some people think a thermal imager uses radiation and may be dangerous, when in fact it actually detects radiation and is just as safe as a digital camera. Visible light is radiation that our eyes can detect. UV radiation is shorter in wavelength than visible light, and infrared radiation is longer in wavelength. The imager is measuring the amount of infrared radiation emitted from surfaces and that amount of radiation is directly related to temperature.
We are all familiar with temperature gun thermometers now, well those collect the same information but only one pixel vs 76,800 with my camera. In essence the image produced is the collection of 76,800 temperatures within the camera's field of view & a Thermal Sensitivity/NETD of <45 mK. My camera also takes a digital picture that can be blended with the thermal data to better show the relevance of the temperature differences.
This isn't just a point and shoot device, there are conditions and variables that have to be accounted for. By definition, Infrared thermography is the process of acquisition and analysis of thermal information from non-contact thermal imaging devices. The process of acquiring the information must be done correctly and with a device that is capable of producing quality images that carry enough information that it can be analyzed. If not done correctly then the results are simply colorful pictures that can be easily misinterpreted.
Once the imager's settings are correct for the conditions of the inspection and all the variables of the environment are taken into consideration, the information can then be collected. The images will go through qualitative and/or quantitative analysis depending on what was inspected. In other words, time at the computer tuning the images to better understand the patterns, differences in temperatures, and how they relate to the real world - good or bad.
What can be found with an IR Scan?
In general my goal is to distinguish and identify thermal patterns due to; moisture, insulation deficiencies, air leakage, structural defects, and poor workmanship.
HVAC - I typically use the thermal imager during a routine inspection to evaluate the HVAC performance, which consists of the return and supply registers looking for the proper difference in temperatures. Additional scanning can be done to reveal more about the HVAC such as the conditioned air leaking into an attic wasting energy and creating condensation issues, improperly installed connections are usually the cause.
MOISTURE - It's common knowledge that water being where it doesn't belong can cause significant damage incurring costly repairs. There are many ways that moisture can enter a home or develop within and go unnoticed for long periods of time. Thermal scans help to reveal problems in early stages so the proper repairs can be made before more damage can occur.
AIR LEAKAGE - Conditioned air leaving or exterior air entering can be uncomfortable and costly. Conditions can be induced by creating pressure or depressurizing the building to highlight the areas in need of proper sealing.
MISSING INSULATION - Fallen, missing or settled insulation allow convection and radiation heat transfer within the walls. The implications of insulation issues are similar to air leakage regarding energy loss and the comfort of the interior.
EXTERIOR WALLS - Stucco and brick are permeable so moisture will get into and behind these materials. If these wall systems were not installed correctly they may still look good on the outside but under the surface there can be extensive damages done.
ROOF MOISTURE - It's not a matter of will a roof leak, it's a matter of when. Gutters and flashings are common points of failure, even brand new roofs will leak if not properly installed. Low slope roofs will retain heat where moisture is under the surface.
PLUMBING LEAKS - Drains are not under water pressure and if the pipes leak it can be slow and long term = hidden and destructive. Galvanized pipes are a good example and even supply lines can have slow pinhole leaks that are not obvious at first.
FLOOD DAMAGE - From plumbing leaks to natural disasters the water damage can be extensive. Using thermography to help see how far the repairs need to go is useful so the remediation can begin faster.
ELECTRICAL ANOMALIES - Outlets and breakers in use will appear in an IR scan, the trick is knowing what is right and what isn't. Overheating components in an electrical system can be signs of greater issues that an electrician should evaluate further.
RADIANT FLOORS - Thermal images can help evaluate for proper installation, leaking hydronic systems or failing electric coils.
TANK LEVELS - Accurately determine how much water, propane or other fluids are inside of a container.
Outdoor and indoor temperature difference of 18 degrees or more is ideal for purposes of most interior wall/ceiling scans. Heat flowing from hot to cold through building materials, walls, and surfaces is easier to see with greater differences. Choosing the right day and utilizing the home HVAC system will yield the best results.
Rain can be helpful if there are moisture intrusion issues with the building envelope but it would prevent an exterior inspection until surfaces were allowed to dry enough.
High winds, air pressure, angles of the sun, time of day, shadows from other buildings or trees all play a part when determining the right conditions for the particular type of inspection to be performed.