The Simpson HHDQ14-SDS2.5 Heavy Holdown is engineered by Simpson for extra-high load structural applications where reliable performance and efficient installation are equally critical. Built from 7-gauge steel and standing 18 3/4 in. tall, this heavy holdown installs directly on the sill plate and is specifically suited for back-to-back applications where eccentricity is a concern. Every unit ships complete with Strong-Drive SDS Heavy-Duty Connector screws and a heavy-hex anchor nut, so the correct fasteners are always on hand and installation can move forward without delay.

Key Features

• Strong-Drive SDS Heavy-Duty Connector screws included - proper fasteners ship with every holdown, eliminating the risk of mismatched hardware on the job site and helping crews work faster with confidence.
• Screws may be installed flush or raised off the mudsill without a reduction in load value - gives installers real flexibility in tight or variable framing conditions without sacrificing structural performance.
• No stud bolts to countersink at openings - simplifies the installation process, reduces labor steps, and keeps work moving at rough framing.
• 7-gauge steel construction with 1/2 in. plate washer - provides the heavy-duty strength and rigidity required for demanding, extra-high load connections in wood-frame construction.
• Simpson Strong-Tie gray paint finish - delivers a durable, consistent coating that helps protect the connector during handling and installation.
• Designed for back-to-back applications - sill plate mounting and symmetrical geometry address eccentricity concerns where paired holdowns are required.

Why This Product

• Everything needed for installation is included - the Strong-Drive SDS screws and heavy-hex anchor nut ship with the holdown, reducing trips to the supply house and keeping your project on schedule.
• Screw installation flexibility without load penalties - because screws can go in flush or raised off the mudsill with no reduction in load value, crews spend less time adjusting and more time building.
• Engineered for the most demanding holdown applications - the HHDQ is purpose-built for extra-high loads where standard holdowns fall short, and the SDS screws reduce fastener slip while providing a greater net section than bolts.
• Versatile sill plate mounting suits complex framing layouts - direct sill plate installation and suitability for back-to-back use make this holdown a practical solution for multi-story, shear wall, and high-uplift framing scenarios.

Specifications

• Model Number: HHDQ14-SDS2.5
• Height: 18-3/4 in.
• Material: 7-gauge steel
• Finish / Coating: Simpson Strong-Tie gray paint
• Install With: (1) 1 in. anchor bolt, (1) heavy-hex anchor nut and (30) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws (screws and heavy-hex anchor nut included)
• Width: 3 in.
• Seat Depth: 3-1/2 in.
• Centerline: 1-1/2 in.
• Screw Offset: 7/8 in.
• Country of Origin: United States

What's Included

Each pack contains (1) HHDQ14-SDS2.5 Heavy Holdown, (30) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws and (1) heavy-hex anchor nut.

Downloads and Resources

• View Specifications

Frequently Asked Questions

What type of loads is the HHDQ14-SDS2.5 designed to handle?

The HHDQ is designed for extra-high loads, making it suitable for demanding structural connections where conventional holdowns may be insufficient.

Do the Strong-Drive SDS screws need to be installed flush with the mudsill?

No. Screws may be installed either flush or raised off the mudsill without a reduction in load value, providing greater installation flexibility on the job site.

Is the HHDQ14-SDS2.5 suitable for back-to-back installations?

Yes. The HHDQ installs directly on the sill plate and is suitable for back-to-back applications where eccentricity is a concern.

What fasteners and hardware are required to install the HHDQ14-SDS2.5?

Installation requires (1) 1 in. anchor bolt, (1) heavy-hex anchor nut, and (30) 1/4 in. x 2-1/2 in. Strong-Drive SDS Heavy-Duty Connector screws. The screws and heavy-hex anchor nut are included with the holdown; the anchor bolt is not included.