Abstract: A rock anchor assembly comprising a tensioning element adapted to be inserted into a bore hole and to be clamped therein, the outer end of which projecting from said bore hole being adapted to be tensioned against a rock wall by means of an anchor plate, the inner end of said tensioning element inserted into the bore hole being provided with a spreading jacket clinging into said bore hole and being adapted for tensioning with the inner end of the tensioning element by means of a spreading wedge upon turning a clamp nut, and wherein said clamp nut is screwed on a threaded tensioning jacket being adapted for tensioning with the outer end of said tensioning element with the aid of tensioning wedge means upon turning the clamp nut. A method of installing said rock anchor in a wall is also provided.