ABSTRACT

Engineered timber buildings require a holistic fire safety strategy that integrates the interaction between the fire-involved structure and the compartment fire dynamics. However, significant research gaps persist, limiting the implementation of a truly holistic design approach. One critical gap is the ignition of an exposed timber ceiling, which can lead to rapid fire spread and abrupt changes in compartment fire conditions, directly impacting the evacuation time. This study investigates the effect of forced convective flow on the ignition delay time of timber under different incident heat fluxes and flow velocities. Tests were conducted in both a normal horizontal (face-up) onentation, and a horizontal inverted (face-down) onentation, representative of an exposed timber ceiling. Results indicate that flow velocity may influence the ignition delay time, particularly in the inverted orientation, which may have implications for predicting the ignition delay time of a mass timber ceiling. Additionally, findings suggest that forced flow may influence whether ignition occurs, introducing stochastic behaviour which is observed under the test conditions used. This study highlights the need for a refined methodology to better charactense ignition behaviour across different mass timber compartment fire scenarios. This improved understanding will support the development of holistic performance-based design for mass timber buildings.