AbstractA study was conducted of the smoke and flow field in a corridor subject to a room fire. The study was conducted using a scale model of roughly 0.35 m in height. The effect of corridor‐exit doorway width was recorded while the room doorway and fire‐room temperature were maintained constant. Smoke was generated from cotton wads soaked with titanium tetrachloride which produces white particles of titanium dioxide. By this means, the smoke layer resulting from the room fire and the corridor flow characteristics were visualized. The results show the lowering interface of the corridor smoke layer with decreasing corridor‐exit door width. Also a four‐layer horizontal counter‐current flow pattern was displayed and shown to result from a restriction (e.g. soffit) at the corridor exit. The mixing of the incoming cold flow and exiting hot flow at the corridor exit was observed to be shedding vortices swept into the cold floor jet. Results based on velocity measurements and smoke observations are presented for the corridor smoke layer height and doorway neutral‐plane heights. The limitations of current predictive models are demonstrated for layer‐heights and flow rates for the room and corrido