Muscling-in on mould

Researchers are testing the feasibility of using radar technology to detect mould behind gypsum wallboard. A common problem, hidden mould can cause serious structural damage and health problems before homeowners discover it.

“Mould is a common problem, especially in humid, southern climates, but people are often not aware of it because it’s occurring behind a painted or wallpapered wall,” said Georgia Tech Research Institute (GTRI) research scientist Victor DeJesus. “Then it’s too late when they realise it. The wallboard must be replaced.”

In addition to degrading structures, mould can emit smelly and potentially harmful compounds into the air, DeJesus added.

Researchers are conducting experiments on damp, mould-infested wallboard panels. Initially, they are using a signal processing algorithm and high-sensitivity, laboratory-size radar system recently developed by GTRI principal research scientist Gene Greneker and senior research scientist Otto Rausch.

They will determine the feasibility of using millimetre-wave, extremely high-resolution radar to detect mould in these panels based on unique characteristics of the mould backscatter signature, extracted by signal processing techniques. Humidity control expert Lew Harriman of Mason-Grant Consulting will also investigate the possibility that X-ray and gamma ray technologies might work. And later, the researchers will examine the effectiveness of these techniques in detecting mould in other indoor building materials, including ceiling tiles typically used in commercial structures.

Ultimately, the researchers hope to produce a small, handheld prototype unit to lay the technical foundation for a commercial product that contractors could purchase for about $1,000 to $2,000 and easily learn to use. They would then test that prototype in actual houses.

Radar expert Greneker envisions a system that would map mould behind a wall. If dampness is indicated by the radar-based device, then a contractor could know more precisely where to probe for damage, he explained.

In an initial experiment that began in January 2004, researchers used a small panel of wallboard, which is very porous, soaked in water and injected with non-toxic fungal spores. In one month’s time, those spores germinated as the wallboard was kept in a high-humidity environment. Mould thrives in damp wallboard because of its paper-based encasing, DeJesus explained.

Researchers then used the radar system to scan the wallboard panel, and they were encouraged by the early results. Now, they are tweaking the algorithm to enable the radar system to discriminate between the mould backscatter signature and nails, boards and wiring that would be found in and behind wallboard, Greneker said. They must also find ways to reduce the system’s cost, while retaining its sensitivity, he added.

This experiment and a larger-scale one that began this spring simulate what might happen to wallboard dampened by a home’s leaking pipe or roof, or from condensation formed by a HVAC system, or even from high-humidity conditions, DeJesus said.

If left unattended, mould can destroy structures and cause serious health problems. The researchers cite a well-known case in which a jury awarded $32 million in damages to plaintiffs in Texas who sued over a neurological condition and asthma their doctors attributed to mould in the home they purchased.