We recently worked on a project in Houston, TX that presented a variety of challenges. We worked closely with a roofing company, legal team and engineering firm to assess a roofs condition for a law suite against the roofing company who performed the installation of the new roof system for our client, the property owner, back in 2016. We performed 3 thermal inspections at various times throughout the night. We also performed a physical inspection thoroughly walking the roof and the interior of the building studying where persistent leaks were occurring. The roofing company that was apart of the process performed 1 core sample on the roof identifying moisture is present. Outside of that, no other destructive testing methods were used.
This “case study” will review the suspicions and reason the inspection was requested, review the science of how the materials act and react with different climates and situations, understand the results and date we collected and discuss how we came to the conclusion we did and tell you a little bit about the equipment we used.
Roof Construction & Back Story
The roofs construction included a 60 mil TPO membrane, 1.5″ of ISO boards and a 2″ Gypsum Deck and is roughly 40,000 sq’. As we understand it, the client had paid for a Built Up roof system (like a cadillac) and the roofing company installed the TPO roof (like a Chevrolet) instead. They were to salvage and reuse the Gypsum deck that was not already saturated. The issue here is that they did not receive the roof they were promised and moisture was entrapped in the roof system upon installation rather than it being properly replaced. Anyone with common since knows that trapping moisture in a building only leads to more problems and head aches down the road…
Due to the TPO roofs components and reflective nature, the roof system will cool down much quicker than other types of roofs. This makes them very difficult to inspect. Even at a direct 90 degree angle where you should see the least amount of possible reflection, the roof system can still have reflective tendencies. Cloud cover during the day and at night affect the roofs ability to radiate, surrounding buildings will reflect temperatures off the roof, and even the wind can cause heat from surrounding areas to blow over the roof system causing false thermal anomalies to appear in the images. Capturing images at various times from different altitudes and angles allows us to collect various data to study and determine if what we are seeing is actually moisture. Of course, the only way to know for certain is to perform a moisture test with either a probe or core sample on suspected areas.
Results & Detailed Report
After thorough investigation and review of the various inspection photos and physical findings, we concluded that this roof system (the TPO and 1.5″ ISO Boards) was installed over an already wet Gypsum Deck from the previous roof system or there was a lot of rain during the installation of the new system. Gypsum is very susceptible to moisture as it tends to soak it up like a sponge. There were 2 leaks located from the inside of the building and are directly correlated in location with moisture found within the roof from the IR inspection. We were also unable to find any other punctures, tears or penetrations indicating that the majority of the identified moisture was in the roof prior to installation. Since the roof was fairly new and the ISO boards were not directly in contact with new water getting into the roof system from the surface, we suspect that we were unable to see the majority of the roofs moisture. Insulation helps to keep energy, both hot or cold, from escaping to the outside of the building. If the Gypsum deck is wet but the ISO boards are not, we will not see our typical IR patterns on the outside, making it difficult to identify how much of the Gypsum is saturated. We suspected moisture to be present in about 25.8% of the roof system and verified roughly about 8.44% total from the walk through.
Some of the patterns we identified were very similar in shape to some of the debris on the roof. The debris and low areas that are prone to ponding water indicate deterioration of the insulation within the roof and would be suspect of current or at least past moisture problems either way. If the ISO boards aren’t soaking up the moisture, when the roof system sweats the moisture on the inside, it can become trapped between the ISO boards and the TPO membrane and can cause these thermal patterns. Our other images did not reflect much change in pattern on other days.
To see all the details and study the report to understand our findings, here is a sample based on this particular project: Project Sample Report
We utilized the DJI Matrice 210RTK with the x4s for visible images and zenmuse xt 640R for the thermal scan. The combination of this equipment gives us adequate flight time, the resolution imaging we need to properly inspect and get the detail we need on a roof system, allow us to see visible and thermal images to understand what we are looking at from the outside in comparison to the thermal scan and help us maintain visual awareness of the drones relation to structures and other objects in the area while flying at night.
To learn more about drones and thermal roof inspections, give us a call today at (214) 842-6000!