Small-scale lab testing is not enough to test fire-retardant-treated wood. Instead, larger, more realistic reaction-to-fire tests show how the materials behave under heavy fire. That is, according to a new white paper published by Woodsafe’s research and development team, which claims that condemning timber for concrete based on insufficient testing would be a step in the wrong direction.
Led by Dr Lazaros Tsantaridis, Limitations of Small-Scale Methods for Testing the Durability of Reaction-to-Fire Performance, addresses the limitations of small-scale testing, particularly the Cone Calorimeter test, in evaluating the performance of fire-retardant-treated wood: “While small-scale tests provide valuable data on material properties, they fail to replicate real-world conditions, often underestimating fire risks.” In addition, “facade systems, for instance, involve complex interactions between components such as insulation, cladding, and air gaps, which small-scale methods cannot capture.”
Dr Tasantaridis, Head of Research at the WRD Fire Impregnated Wood Research Centre, said Cone Calorimeter tests, which use small, flat samples under uniform heat exposure, fail to capture factors like flame spread, material interactions, and dynamic fire conditions like in large-scale scenarios: “The inherent oversimplification in small-scale testing often leads to underestimating or misjudging fire performance of materials and systems, highlighting their inadequacy for ensuring comprehensive fire safety.”
Instead, medium-scale testing like the Single Burning Item (SBI)—now required in updates to EN 16755—where materials are tested in a three-dimensional corner construction—and full-scale fire tests, like SP Fire 105, provide far more balanced risk assessments. “These tests mimic real conditions and provide more reliable results,” the paper said. “It is crucial to understand how different materials and facade systems behave at the beginning of a fire.”
That’s because factors such as cladding, insulation, and air gaps play a crucial role, according to Dr Tasantaridis. “Large-scale tests allow for the analysis of flame spread, heat development, and other critical parameters under the most realistic conditions. These tests not only provide a better understanding of how fire-retardant-treated wood behaves in a fire but also help to strengthen confidence in wood structures as a safe and sustainable building solution.”
- Please Note: Woodsafe is one of Europe’s leading manufacturers of fire-impregnated wood products. To learn more about the testing, click here to download the White Paper.