As bio-based insulation products become more widely used in buildings, a better understanding of their smoldering fire behavior is required. Smoldering is a slow, low-temperature combustion process influenced by material composition, density, porosity, and other physical characteristics. In this study, although all tested bio-based insulation materials were susceptible to smoldering, significant differences were observed in smoldering propagation rates, internal temperature development, peak temperatures reached, gas production, and post-test mass loss. Some materials exhibited slow sub-surface smoldering with moderate internal temperature rise, while others showed faster propagation and higher thermal and gas emission levels. These findings demonstrate that smoldering performance cannot be generalized and must be assessed through material-specific fire parameters to improve fire safety.

These findings provide qualitative insight into smoldering mechanisms in bio-based insulation materials and highlight the need for material-specific fire safety assessment.