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HD Holdown

HD

On This Page

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.

Key Features

  • 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

Material

  • See table

Finish

  • Simpson Strong-Tie gray paint; HDG available

Installation

  • 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 12.1.3.2)
  • 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

Related Literature

Product Information Table

Fastener Production Information and Stuff & Things
Model No. Base/Seat Thickness (in.) Ga. HB (in.) SB (in.) W (in.) H (in.) B (in.) CL (in.) SO (in.) Coating/Material Packaging Qty.
HD12 3/8 3 7 4 3 1/2 20 5/16 4 1/4 2 1/8 3 5/8 Simpson Strong-Tie Gray Paint 1
HD19 3/8 3 7 4 3 1/2 24 1/2 4 1/4 2 1/8 3 5/8 Simpson Strong-Tie Gray Paint 1

Load Tables

    These products are available with additional corrosion protection. Additional products on this page may also be available with this option, check with Simpson Strong-Tie for details.

HDB/HD Holdowns Load Table
  1. 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.
  2. 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.
  3. HD19 with 1 1/4" anchor rod requires No.1 post (or better) to achieve published loads.

Code Reports & Compliance

Drawings

PDF DWG DXF RFA IFC SAT