Key Features

Predeflected Body The body is predeflected during manufacturing, which helps virtually eliminate deflection under load from material stretch. That matters when you need a tighter, more predictable holdown connection in shearwall and braced-wall work. Screws Included This Simpson Strong-Tie holdown comes with the required Strong-Drive SDS heavy-duty connector screws and crescent washer. You are not chasing down separate fasteners or guessing what hardware the connector was engineered around. Cleaner Post Connection By using SDS screws instead of stud bolts through the post, the connection installs easier and avoids countersinking bolts at openings. That can save time and preserves more net section in the wood member compared to bolted setups.

Overview

The Simpson Strong-Tie HDU4-SDS2.5 holdown is a galvanized steel holdown designed for wood-to-wood lateral load connections in shearwalls, braced-wall panels, and other high-wind construction details. This is a holdown designed for resisting uplift and tension forces in wood framing. Model Number: HDU4-SDS2.5. If you are tying a wood post or stud assembly back to the foundation and want a connector built around screw installation instead of field-assembled bolt hardware through the post, this is the setup.

For this specific HDU4-SDS2.5 version, Simpson Strong-Tie builds the connector from 14-gauge steel with a Zinc Galvanized, G90 finish. The connector measures 3 inches wide and 10-15/16 inches high, with a 3-1/4 inch base width. It installs with a 5/8 inch anchor bolt and includes (10) 1/4 inch x 2-1/2 inch Strong-Drive SDS Heavy-Duty Connector screws plus (1) crescent washer. That included hardware is a real advantage because the connection is being installed with the fasteners Simpson intended, not a substitute pulled from a mixed hardware bin.

The big selling point on the HDU line is the predeflected seat. In practical terms, that means the body is formed to reduce connector movement caused by material stretch once the load comes on. On a wall line where movement control matters, less connection deflection helps the assembly behave more like the engineer intended. This is one of those details that may not look dramatic on the shelf, but it matters when the load path is doing real work.

Another reason pros like this style of holdown is the switch from post bolts to SDS connector screws along the member. Simpson specifically notes that the screws install easily, reduce fastener slip, and provide a greater net section area of the post compared to bolts. In plain language, you are not drilling large through-holes in the wood member the way you would with a traditional bolted holdown. That can simplify installation and avoid some of the layout headaches around openings and tight framing conditions.

The HDU4-SDS2.5 is also built for jobsite practicality. Simpson states there are no stud bolts to countersink at openings, which is a small detail until you are working around finished wall conditions, narrow framing spaces, or retrofit situations. The product also requires no additional washer beyond what is included. Simpson recommends installing the SDS screws with a low-speed, high-torque drill equipped with a 3/8 inch hex-head driver, which tells you this connector is meant to go in with standard, accessible tools rather than a specialty setup.

In the Simpson lineup, the HDU series is explicitly intended for shearwalls and braced-wall panels, plus other lateral applications, and the web data lists high-wind construction as a primary application. The galvanized finish makes this standard HDU4-SDS2.5 appropriate where a zinc-coated connector is specified. If you need added corrosion protection, Simpson also offers related HDG versions in the broader HDU family, but this exact SKU is the standard G90 galvanized model.

Who should buy it? This connector makes the most sense for builders, framers, remodelers, and code-driven residential contractors working from engineered plans that call for an HDU4-size holdown. It is also a good fit for serious DIYers doing permitted structural work, provided the project documents specifically call for this connector and fastener pattern. Bottom line: if your plan set calls for a Simpson Strong-Tie HDU4-SDS2.5 holdown, this one gives you the correct screw-based configuration, the included hardware, and the reduced-deflection design that makes the HDU series worth using.

Faster Structural Tie-Down Installation

This holdown is built to make a structural connection easier to install without giving up the hardware the design depends on. Using SDS connector screws helps speed installation compared to traditional post-bolt layouts and cuts down on field guesswork.

• Designed for shearwalls, braced-wall panels, and other lateral applications
• Installs with a 5/8 inch anchor bolt and included 1/4 inch x 2-1/2 inch SDS screws

Reduced Movement Under Load

The predeflected body is the feature that separates this connector from basic formed holdowns. It is there to help limit deflection caused by material stretch, which is exactly what you want in a tension connection that is expected to stay tight and predictable.

• Predeflected seat virtually eliminates deflection under load
• No additional washer required for the HDU installation

Designed Around the Right Fasteners

Simpson supplies the connector with the SDS screws and crescent washer because the connection values depend on the correct hardware. That is a better setup than piecing together a structural connection from substitute screws or generic bolts.

• Includes the specified Strong-Drive SDS heavy-duty connector screws
• Uses screw installation to avoid stud bolts that need countersinking at openings

What’s in the Box

• (1) Simpson Strong-Tie HDU4-SDS2.5 holdown
• (10) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws
• (1) crescent washer

Anchor bolt is required for installation. This model installs with a 5/8 in. anchor bolt.

Key Specifications

Compatibility

Framing Material Designed for wood-to-wood connections. Fastener System Engineered to use Strong-Drive SDS Heavy-Duty Connector screws. The required screws are included with this holdown. Anchor Requirement Installs with a 5/8 in. anchor bolt.

Built For

High-Wind Construction Shearwalls Braced-Wall Panels Residential Framing Structural Retrofit General Contracting Carpentry Remodeling

Pro Tip

Use a low-speed, high-torque drill with a 3/8 inch hex-head driver for the included SDS screws. It gives you better control seating the screws fully in the connector without fighting the tool.

Warranty & Support

No warranty is listed for this product in the provided product data.

Tool Nut’s Take

Tool Nut’s Take

Simpson Strong-Tie HDU4-SDS2.5 Holdown Done the Right Way

If your plans call for an HDU4, this is the version you want because it gives you the correct screw package, reduced-deflection design, and a cleaner install than old-school bolted holdowns.

• Who it’s for: Framers, builders, remodelers, and engineers working on shearwall or braced-wall details in wood construction.
• Why it stands out: The predeflected body and included SDS connector screws make this more jobsite-friendly and more predictable under load than a basic formed connector with substitute hardware.
• Worth knowing: This is a structural connector, not a general-purpose bracket. Buy it because your plans or load path call for this exact holdown and install it with the specified 5/8 inch anchor bolt.

Common Questions

• What is this connector used for? It is used in shearwalls, braced-wall panels, and other lateral load applications where a wood member needs a holdown connection to resist uplift and tension forces.
• Does it use nails or screws? This model uses Strong-Drive SDS Heavy-Duty Connector screws, and the included quantity for this SKU is ten 1/4 in. x 2-1/2 in. screws.
• What anchor bolt size does it require? The provided product data states installation with a 5/8 in. anchor bolt.
• What finish does this version have? The HDU4-SDS2.5 uses a Zinc Galvanized, G90 finish.