West Virginia University Researchers Find Ways to Use Low-Grade Hardwoods in Cross-Laminated Timber

Joseph McNeel, a professor at West Virginia University (WVU) and director of the WVU Appalachian Hardwood Center at the Davis College of Agriculture, Natural Resources, and Design, has been testing the effectiveness of yellow poplar—an abundant West Virginia species—as a source of engineered wood building materials. Yellow poplar grows straight, has small limbs, and processes easily, making it well suited for construction.

Professor McNeel noted that, “Half of the hardwood harvested for sawtimber in West Virginia is considered low-quality lumber because it has too many knots and other defects. It is used for pallets, boxes, railroad ties, and flooring. But you can take those low-quality hardwoods and create something with significant added value.”

Research conducted by McNeel and his colleagues suggests that certain Appalachian hardwoods, like yellow poplar, work well in structural applications. “One reason we liked yellow poplar was because it has been tested extensively in the past for structural applications,” he said.

In the lab, the team has created panels of three, five, and seven layers using a press that can apply 250 pounds of pressure per square inch. The researchers tested the panels’ bending and breaking strength and subjected samples to harsh conditions like water saturation and dehydration. Tests were performed multiple times to see if the glue bonds held and results indicated the panels will perform well in construction.

The next step will be to get yellow poplar accepted as a permittable raw material by the American Panel Association. At that point, CLT manufacturing companies will be able to use yellow poplar CLTs in commercial construction.