Expanded polystyrene insulated panel is a building material that is manufactured by adhering light gauge sheet metal to both sides of a core of expanded polystyrene. This report examines how the combustible core of expanded polystyrene insulated panel behaves when exposed to a radiant heat source at elevated temperatures. A number of fires in commercial/industrial buildings constructed from this product, mainly in Europe, have highlighted concerns about its performance and safety. A series of experiments were conducted which simulated the situation of a flue passing through a roof or ceiling in a building that was constructed from expanded polystyrene insulated panel. Specimens of the product were placed immediately adjacent to a stainless steel flue with surface temperatures ranging from 600-900°C approximately. The behaviour of the expanded polystyrene core of the insulated panel was monitored. The primary conclusion of the project was that, although the expanded polystyrene core of the specimens ignited for the higher flue temperatures, there was no evidence of the combustion spreading through the core. In all cases, the flaming died out after the core had shrunk far enough away from the flue.