The Simpson 20-5/16 in. Bolted Hold Down Anchor HD12 is a heavy-duty structural connector from Simpson Strong-Tie, engineered to generate high allowable loads in both vertical and horizontal wood construction applications. Built from 3-gauge steel with a 3/8 in. steel base, this bolted holdown installs directly into posts or columns and can be mounted back to back when eccentricity is a concern, giving structural professionals a dependable solution for demanding shear wall and post-base tie-down assemblies.

Key Features

• High-capacity, low-deflection holdown design - delivers strong, stable load transfer while minimizing movement under load, keeping structural connections tight and code-compliant over time.
• Self-jigging construction - automatically positions the connector to meet the code-required minimum of seven bolt diameters from the end of the post when installed flush with the sill plate, reducing layout errors and speeding up installation.
• Flexible mounting options - may be raised and installed off the sill plate, allowing the connector to accommodate varying framing conditions and field adjustments without compromising performance.
• Back-to-back installation capability - two HD12 units can be paired when eccentricity is an issue, enabling balanced load transfer in applications where force alignment is a structural requirement.
• 3-gauge steel body with 3/8 in. steel base - the heavy-gauge construction provides the rigidity and strength needed for high-load post and column tie-down applications in wood-framed structures.
• Simpson Strong-Tie gray paint finish - provides a durable protective coating suited for interior structural use, maintaining connector integrity throughout the service life of the assembly.

Why This Product

• Built for high-load structural demands - the HD12 is specifically designed to create high allowable loads in both vertical and horizontal applications, making it a reliable choice for shear walls, post tie-downs, and column anchoring in wood construction.
• Simplifies code compliance on the job site - the self-jigging feature takes the guesswork out of bolt placement by automatically maintaining the code-required minimum spacing from the post end, reducing the risk of costly installation errors.
• Adaptable to real-world framing conditions - the ability to install the HD12 flush with or raised off the sill plate means contractors can work around existing framing variables without needing a different connector or custom solution.
• Engineered by a trusted name in structural connectors - backed by Simpson Strong-Tie design standards and manufactured in the United States, the HD12 brings proven engineering to critical structural connections in residential and commercial wood framing.

Specifications

• MPN: HD12
• Gauge: 3
• Base/Seat Thickness: 3/8 in. steel
• SB: 4 in.
• Coating/Finish: Simpson Strong-Tie Gray Paint
• Install With: Install with 1 in. or 1-1/8 in. anchor bolt and (4) 1 in. stud machine bolts
• Hole Bottom: 7 in.
• Width: 3-1/2 in.
• Height: 20-5/16 in.
• Seat Depth: 4-1/4 in.
• Centerline: 2-1/8 in.
• Screw Offset: 3-5/8 in.
• Country of Origin: United States

Frequently Asked Questions

How is the Simpson HD12 holdown installed?

The HD12 is installed with bolts into posts or columns. It requires 1 in. or 1-1/8 in. anchor bolt and (4) 1 in. stud machine bolts for proper installation.

Can the HD12 be installed off the sill plate?

Yes. The HD12 may be raised and installed off the sill plate, providing flexibility to accommodate various framing conditions on the job site.

What does "self-jigging" mean for the HD12?

The self-jigging design ensures the code-required minimum of seven bolt diameters from the end of the post is automatically achieved when the holdown is installed flush with the sill plate, simplifying installation and helping maintain code compliance.

Can two HD12 holdowns be used together when eccentricity is a concern?

Yes. The HD12 can be installed back to back when eccentricity is an issue, allowing for balanced load transfer in applications where alignment of forces is a structural concern.