Fred Turner, Consulting Structural Engineer for many years with the California Seismic Safety Commission summarizes the hazards
in these
single rooms, perched on top of concrete or steel supports: «i) If unattached
classrooms move relative to their stair systems (which can be structurally separated from the
classroom) doors that
open outward can be prevented from
opening by creation of an offset, gap or obstruction that forms between the
classrooms and the stairs during the earthquake, potentially obstructing egress.