Thermal Imaging: Maximize Your Investigation
Thermal imaging cameras can help maximize the potential for identifying conditions that may be of interest to those engaged in restoration and remediation. Readers of R&R are familiar with the use of thermal imaging cameras to search for and document moisture, as the camera helps speed up the investigation while providing guidance for positioning a moisture meter to confirm areas of moisture. However, there are a number of other ways that your thermal imaging camera can be used.
When properly constructed and maintained, buildings shouldn’t accumulate moisture. But sometimes something as simple as an area of missing insulation or air infiltration through an opening can result in a space with a temperature below the dew point. By calculating the dew point temperature, and searching for areas where the temperature is below the dew point, areas of condensation can quickly be identified.
When condensation moisture remains inside a building cavity or wall for more than a few days, mold can begin to grow. As a rule of thumb, a 20°F drop in temperature results in the doubling of relative humidity. It is not uncommon for exterior walls with surfaces to experience these types of temperature differences. That means a relative humidity of 50% in the indoor air can result in condensation when it comes in contact with one of these cold surfaces. Missing insulation can result in serious moisture condensation problems, but even if insulation is in place “leaky” walls will often permit air flow to “air wash” through the insulation.
Air washing reduces the effectiveness of insulation but can also result in damage from moisture condensing in the insulation. Air washing can be diagnosed using thermal imaging, in combination with a negative pressure in the building, when temperature differences between the inside and outside are at least 20°F. If a strong wind is blowing outside, nature can provide the necessary pressure, but restoration contractors with thermal imaging cameras and air filtration devices (AFDs) for performing remediation are in a perfect position to perform these types of diagnostics even if the wind isn’t blowing. Of course, anytime negative pressure is used in a building, care needs to be taken to prevent the risk of carbon monoxide poisoning or flame rollout from combustion appliances due to back drafting.
Another common condition that is able to be diagnosed using a thermal imaging camera is ice damming. Ice dams form when heat escaping from the structure warms an area thereby causing snow on the roof to melt. If the liquid water encounters a cold area (such as the roof overhang) where it refreezes, then a dam of ice can form. Additional water is trapped behind this dam and backs up on the roof soaking under the shingles and sheathing, allowing it to enter into the building. Thermal imaging cameras can be used to locate hot spots on a roof when it is cold outside, but when there isn’t any snow buildup on the roof. These are the areas where ice dams are likely to form. The hot spot represents an area where snow is likely to melt and refreeze into an ice dam. Looking for cold spots on the inside ceiling may not only indicate an area of missing insulation likely to result in an ice dam, but may also give way to an area where condensation moisture forms as well.
Sometimes, animals will get into an attic and build a nest or tunnel through the insulation. This causes damage to the insulation, but this also increases the likelihood of moisture damage as described above. The tunnels and compacted areas made by the invading animals are frequently visible by examining the ceiling with a thermal imaging camera. The undamaged areas tend to have a fairly even temperature, while the areas of the damage may even show evidence of the path the animal is traveling as it goes through the attic. This may even provide clues as to the way it is getting in and out of the attic. Of course, as with moisture detection, the thermal imaging camera only provides evidence of anomalies. Additional investigation is required to see what has actually occurred.
As with moisture investigations using thermal imaging, the diagnostic capabilities of the operator require training and experience. Without an appropriate understanding of how to use these tools properly, there is great potential for them to be misused. Every beginner thermographer should have training so they know how to use the camera. This basic understanding can then be used to observe a wide variety of building anomalies. While in many cases these anomalies turn out to be no problem, they often provide vital clues to preexisting conditions and even information toward preventing future problems.