The mutual positioning of longitudinal building components includes two clamps routed towards each other about an axis of rotation. Each of the two clamps comprises two limbs defining an opening located therebetween. The opening is selectively narrowed or expanded by elastic deformation of the clamps such that a longitudinal building component which is introduced into the opening of the clamp is prefixed. The two clamps are provided with a bore which is coaxial to the axis of rotation and penetrates the limbs of the clamps. The two clamps are borne on a shaft and blocking means are provided to selectively block the rotatability of the two clamps about the axis of rotation and press the limbs of each clamp against the longitudinal building component inserted into the opening of the clamp. One of the two clamps is S-shaped such that it defines two diametrically opposite clamp openings.
