New microwave radar technology could detect hidden moisture in walls

Moisture trapped within the walls of a home can cause major problems.

It creates the perfect conditions for mold to grow, damages building materials, reduces energy efficiency and can even harm human health by worsening air quality.

The key to preventing these problems is to detect moisture early before it causes major damage.

Now researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) have developed a microwave radar system that can find and measure moisture in walls without having to remove drywall or paneling.

This non-invasive method makes it quicker and easier to identify moisture problems before they worsen.

The team’s work was recently published in IEEE Xplore and presented at the 2024 IEEE Radar Conference.

Microwave radar emits signals that reflect off materials and return to the radar system.

These reflections can reveal details about the materials, such as their moisture content. In contrast to visible light, microwaves can penetrate deeper and are therefore ideal for looking inside walls.

Most homes are built from wood frames and wet wood is a breeding ground for mold. The researchers focused on detecting moisture in Oriented Strand Board (OSB)a common material used in wall construction.

By analyzing how the radar signals bounce off the wood and other layers in the wall, the system can measure moisture levels and even detect which parts of the wall are wet.

The ORNL team began testing small pieces of OSB. They dried the wood in a kiln, conditioned it to a specific moisture content, and then used radar to measure the moisture content. The results were consistent with readings from traditional portable moisture meters, with a difference of less than 3%.

Next, the researchers added a layer of drywall in front of the wood to see if the radar could still detect moisture. The radar successfully measured the moisture in the wood through the drywall, proving that it works under real-world conditions.

The team then developed a small, portable version of the microwave radar system for practical use. This version can scan walls, roofs and even foundations to find hidden moisture. Using frequencies between 10 and 15 gigahertz, the system is lightweight, easy to set up and adaptable for public use.

The researchers plan to expand their testing to complete wall assemblies using different materials such as brick and vinyl siding. Their goal is to make the system affordable and widely available so homeowners and inspectors can use it to detect moisture problems early.

This technology can address small moisture problems before they cause major damage, saving homeowners time, money and stress. It could also help homebuyers identify hidden problems during inspections, providing peace of mind for their investment.

“We have developed a system that is portable, easy to use and designed specifically for residential homes,” said Philip Boudreaux of ORNL. “There is still a lot of work to be done, but this technology has the potential to make a big difference in detecting and preventing moisture damage.”

With promising results so far, this innovative radar system could soon become a valuable tool for keeping homes safe, dry and energy efficient.

Source: Oak Ridge National Laboratory.