In this study, externally venting flames have been examined during two series of full scale flashover fires. The purpose of the work is to investigate the likelihood of
external fire spread from a burn room window with standard glass, when the external facade is non-combustible. The effects on externally venting flames of internal
ventilation conditions, burning rate, burn room size and wind have been studied in detail. Secondary fires and glass breakage have been examined.. Repeatable experimental data and reliable information on externally venting flames have been generated for numerical model validation and performance based design code development.