While invasive testing methods are sometimes necessary to determine the source and extent of moisture problems in buildings, there is a whole range of tools available to aid initial diagnosis. Electronic moisture meters, surface thermometers, hygrometers and data loggers all have their part to play. For experts like Brick Tie Preservation in Yorkshire (UK), these are the standard tools of the trade. The company also has its own laboratory for saltpetre analysis and gravimetric testing of masonry samples. With such a well-equipped facility, why did the company choose to add thermography to its arsenal?
The answer to this question lies in the ability to instantly "step back" and integrate features and defects that have an influence on the moisture problem; these details can be seen immediately on a thermal image, which reveals variations in heat transfer and retention. Bryan Hindle, CEO of Brick Tie Preservation, likens his thermographic camera to a time machine, enabling him to learn about the history of a building.
He had been interested in thermography for some time and, after seeking advice from other professionals in his field, decided to enrol on a course run by Thermographic Consultancy Limited (TCL) in Swindon to find out more about the technology.
"While there's nothing rocket science about building thermography, it does require a good understanding of how it works and what affects the equipment and results," explains Bryan Hindle. "I think a Level 1 qualification in thermography is perfect for anyone starting out in this field. In fact, I wouldn't use an IR camera in my work without this training."
The next step was to choose the most suitable thermographic camera. Following his training, Bryan realized that an entry-level model would be a pittance for his company. While a simple model is sufficient for solving simple problems, it doesn't offer the performance or rich functionality required to detect the complex problems revealed by subtle temperature variations.
Thanks to the guidance of TCL expert Stuart Holland, himself a Level III thermographer, Bryan Hindle finally opted for the Flir T420bx, equipped with a wide-angle lens, as his company operates largely inside buildings.
"Flir makes quality products and has a good network of professional trainers. That's what I like in a manufacturer. It's responsible and proactive," confirms Bryan Hindle. "I looked at other brands, but this model offers the ideal combination of functionality, sensitivity and resolution. Having used inexpensive pistol-type models, I find the ergonomics of the pivoting lens and handle much more comfortable."
"Good sensitivity is a particularly important criterion, because I can't rely on high temperature differentials and I have no choice of working conditions," he adds. "Preparation is of little use if, for example, the doors and windows of a building are wide open when I arrive. In that case, working conditions are far from ideal."
Limiting destructive testing
Although thermography cannot directly diagnose situations such as rising damp, it does help Bryan Hindle to refine his judgment of a problem. He feels it adds value to his diagnosis. This is important, because many damp problems are influenced by work carried out in the past, which is often hidden behind plaster or other finishes. The owner or tenant may not even be aware of them.
"Thermography helps me to make fully informed decisions about whether or not tedious, destructive testing is necessary. I can get this information on site, and usually with immediate results," says Bryan. "Thanks to this technology, I was recently able to show an inspector that a house didn't need damp-proofing or extensive work, as it was simply a condensation problem."
In this particular case, Bryan Hindle used his Flir T420bx in combination with his Flir MR77 moisture meter. Both devices are equipped with Meterlink, a function that incorporates the moisture meter's measurements into the thermal image.
"I was able to give my customers an image showing dew points with relative humidity superimposed on a color isotherm taken on site, so they could see the result of live moisture meter measurements," continues Bryan Hindle. "It's a particularly valuable communication tool, and frankly, I wouldn't dream of buying a camera without it. I hate reports that confuse customers. That's why providing the IR image with a clear explanation of what's going on works so well."
Knowledge acquisition
Not only is the Flir T420bx from Brick Tie Preservation an important diagnostic aid, it also enables the company to acquire scientific knowledge. For example, it has recently been used to better understand how saltpetre affects the thermal characteristics of masonry, as well as how stale air, common in winter, contributes to increased humidity.
In this particular project, Bryan Hindle used Flir Systems' patented multispectral imaging technology, MSX, to visually represent thermal effects. MSX intercepts visual data from the integrated digital camera and radiometric data from the thermal camera. Internal software analyzes the image and superimposes its key elements in the form of a high-contrast "skeleton" of the thermal image.
"Thanks to MSX technology, the edges of the passages, the bedding and the passage/wall junction appear clearly on the image. I also used Fl'or Systems' excellent tools to materialize some of the measurement plots to highlight the temperature gradients, as well as the apparent maximum and minimum temperatures on each of them," explains Bryan Hindle.
A multitude of applications
For Brick Tie Preservation, the main benefits of thermography lie in its ability to reveal missing or faulty insulation, as well as locations at risk of condensation. It can also identify thermal bridges such as blocked cavities. In older buildings, it also helps to find concealed timber framing and half-timbering, blocked openings and leaks.
Recently, the flexibility of this camera enabled Bryan Hindle to find a leak in a central heating system comprising a hundred meters of piping under the first floor screed.
"Thanks to my thermographic camera, I spotted the anomaly in just a few minutes. When the heating was turned back on, the customer and I saw the spot grow and then cool when cold water was circulated," adds Bryan Hindle. "All this was detected without having to move furniture, carpets or carpet pad. The customer was delighted that the problem was spotted without having to rip anything out."
"I've done without thermography for years, but that wouldn't be the case today," he concludes.
Learn more: www.flir.fr