A building structure includes a framework of: (a) metal studs having walls that define an interior channel; (b) a cellular backing material extending lengthwise within the interior channel of at least a portion of the metal studs; (c) a thermally insulating layer extending over multiple metal studs; (d) fasteners extending through the thermally insulating layer, through a wall of a metal stud and into the cellular backing material within the interior channel of the metal stud; and (e) a cladding attached to the framework of metal studs by means of the fasteners.