Upward Fire Spread Rate Over Real-Scale EPS ETICS Façades

The expanded polystyrene (EPS) façade has been widely used to save building energy, but it has also caused many severe facade fire accidents worldwide. Especially for aged buildings, the naturally weathered exterior surface layer can further increase the facade fire risk and the fire spread rate (FSR). In this work, a series of real-scale EPS External Thermal Insulation Composite System (ETICS) façades are tested via the JIS A 1310 standard. The EPS thickness varies from 100 to 300 mm, density changes from 15 kg/m³ to 30 kg/m³, and heat release rate (HRR) of window spilled flame ranges from 600 kW to 1100 kW. Tests showed that the surface cement layer was quickly damaged by a spilled flame that provided negligible fire resistance for the internal flammable EPS panel. The measured upward FSR increases with the rising of HRR and with the decreasing EPS thickness like the thermally thin material. An empirical correlation of instantaneous upward FRS is proposed, FSR = 0.22Φ + 3.45 [cm/min], where Φ is a modified fire propagation index derived from the experimental temperature distribution. In addition, a simple prediction method for FSR is proposed for the façade fire and verified by the experimental data. This work provides a useful method to quantify the upward façade fire propagation, which also helps evaluate the fire risk and hazard of EPS ETICS façade prior to the costly large-scale tests and installation.