Fire hazard of an architectural feature with double-skin façade is a concern. An identified scenario of having a post-flashover room fire adjacent to the façade was studied experimentally in a rig of 6 m tall. Eight tests of cavity depths including a wide value of 2 m, normal values of 1.5 m and 1 m and a narrow value of 0.5 m under a room flashover fire of 1200 kW were carried out. From the measured air temperature profiles inside the façade cavity, the chance of breaking the interior glass pane above the fire room is therefore very high. Copyright © 2012 John Wiley & Sons, Ltd.