Abstract: An improved door assembly includes a door frame having a door jamb and a door having a fixed portion including a hinged side and a locking side where the hinged side of the door is hinged to the door frame. At least one of the hinged side and the locking side of the door has at least one pivotable door portion configured to pivotably move between a retracted position inside the door and an extended position that extends inside at least one complementary shaped channel within the door jamb of the door frame to interlock the door and the door frame.