The HD is designed to create high allowable loads for both vertical and horizontal applications in wood construction. This holdown is installed with bolts into posts or columns. The HD can be installed back to back when eccentricity is an issue.
High-capacity low-deflection holdown
Self-jigging, ensuring the code-required minimum of seven bolt diameters from the end of the post when installed flush with the sill plate
May be raised and installed off the sill plate
Simpson Strong-Tie gray paint; HDG available
See General Notes for Holdowns and Tension Ties
Bolt holes shall be a minimum of 1/32" to a maximum of 1/16" larger than the bolt diameter (per 2015/2018 NDS, section 184.108.40.206)
Stud bolts should be snugly tightened with standard-cut washers between the wood and nut (BPs are required in the City and County of Los Angeles)
Standard-cut washer is required under the anchor nut for HD12 with 1" anchor and HD19 with 1 1/8" anchors
To achieve published loads, machine bolts shall be installed with the nut on the opposite side of the holdown. If this orientation is reversed, the Designer shall reduce the allowable loads shown per NDS requirements when bolt threads are in the shear plane.
All references to bolts are for structural quality through bolts (not lag screw or carriage bolts) equal to or better than ASTM A307, Grade A.
HD19 with 1 1/4" anchor rod requires No.1 post (or better) to achieve published loads.