Simpson HDU8-SDS2.5 16-5/8 in. Galvanized Predeflected Holdown with Strong-Drive SDS Screws is a structural holdown connector engineered by Simpson for demanding lateral load applications in wood-frame construction, including shearwalls and braced-wall panels. The predeflected body is manufactured to virtually eliminate deflection under load due to material stretch, delivering a more consistent and reliable connection from installation through long-term service. Paired with included Strong-Drive SDS Heavy-Duty Connector screws and a crescent washer, this holdown is ready to install right out of the package with no supplemental fastener sourcing required.

Key Features

• Predeflected body - virtually eliminates deflection due to material stretch under load, so the holdown maintains holding strength more consistently once installed and engaged
• Strong-Drive SDS Heavy-Duty Connector screws included - ensures the correct fasteners are always used, removes the guesswork from the job site, and keeps installations code-consistent
• SDS screws install easily and reduce fastener slip - faster installation compared to traditional bolted connections, with improved connection performance through reduced slip at the fastener interface
• SDS screws provide a greater net section area of the post compared to bolts - more of the post's structural cross-section is preserved, supporting a stronger overall connection
• No stud bolts to countersink at openings - simplifies installation at wall openings and reduces labor time on the job site
• 10-gauge steel construction - delivers the material thickness and rigidity required for high-demand structural holdown applications
• Zinc Galvanized G90 coating - provides enhanced corrosion resistance, making this holdown suitable for use in environments where moisture exposure is a concern

Why This Product

• Built-in deflection control from the factory - because the holdown body is predeflected during manufacturing, buyers get a connector that performs more predictably under load without relying on field adjustments to compensate for material stretch
• Complete fastener kit included - the package contains (20) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws and (1) crescent washer, so contractors have everything needed to complete the connection without sourcing additional hardware separately
• Screw-based installation over bolts means less post material removed - the SDS screws preserve a greater net section area of the post compared to bolts, which translates to a stronger, more intact structural member at the connection point
• Simpson engineering and quality standards - designed, tested, and manufactured to meet the performance and quality expectations that structural wood-frame contractors rely on for holdown applications in lateral force-resisting systems

Specifications

• Model Number: HDU8-SDS2.5
• Height: 16-5/8 in.
• Gauge: 10
• Coating/Finish: Zinc Galvanized, G90
• Install With: Install with 7/8 in. anchor bolt and 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws (included)
• Country of Origin: United States

What's Included

Each pack contains (1) HDU8-SDS2.5 Predeflected Holdown, (20) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws and (1) crescent washer.

Downloads and Resources

• View Specifications

Frequently Asked Questions

What does "predeflected" mean and why does it matter?

The HDU8-SDS2.5 is pre-deflected during the manufacturing process, which virtually eliminates deflection under load due to material stretch. This means the holdown maintains its holding strength more consistently once installed and loaded, resulting in a more reliable and stable connection.

Why does this holdown use SDS screws instead of bolts?

The 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws install easily, reduce fastener slip, and provide a greater net section area of the post compared to bolts. This improves both the ease of installation and the overall strength of the connection.

Are the fasteners included with this holdown?

Yes. The package includes (20) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws and (1) crescent washer, ensuring that the proper fasteners are always used with the holdown.

What material and corrosion protection does the HDU8-SDS2.5 have?

The HDU8-SDS2.5 is made from 10-gauge steel and features a Zinc Galvanized (G90) coating, which provides extra corrosion resistance for long-term durability in demanding construction environments.

Note: Product dimensions and/or screw or bolt holes may differ from picture. Please see item description for specifications.