Abstract: A uni-directional slack adjuster is incorporated into a hold-down tension rod or strap, such as a hold-down anchor bolt for bolting a shear wall on one floor to a shear wall or foundation wall below, when a wood floor joist assembly is in between. The slack adjuster eliminates bolt slack so that in the event of an earthquake or hurricane, the sill plate is positively anchored with no vertical bolt play, eliminating much of the cosmetic damage that is often done to the wallboard and other finished surfaces due to distortion of the wallboard framing as the sill rises abruptly until it reaches the end of travel on the hold-down bolts. The slack adjuster comprises a link in the tensioner and non-reversibly either expands or contracts axially depending on the particular embodiment.