The Simpson Strong-Drive SDWH Timber-Hex Hot-Dip Galvanized Screw is a heavy-duty structural fastener engineered for demanding marine, coastal, and outdoor timber applications. With a 0.276 in. shank diameter and 4 in. length, this large hex washer head screw delivers reliable wood-to-wood connections in environments where corrosion resistance is critical - including structural pilings, piers, docks, and boardwalks. The Hot-Dip Galvanized, Class C coating provides a thick, durable zinc barrier suited for saltwater exposure and harsh outdoor conditions, making it a go-to choice for pile connections and coastal construction where long-term fastener integrity is non-negotiable.

Key Features

• Hot-Dip Galvanized, Class C coating - provides a heavy zinc layer designed to resist corrosion in marine, coastal, and wet outdoor environments where standard coatings would fail prematurely
• 0.276 in. shank diameter with serrated threads - the serrated thread profile bites aggressively into timber, creating a strong mechanical grip that resists pull-out forces in structural pile and dock connections
• SawTooth point - self-drilling tip starts fast and eliminates the need for predrilling, saving significant labor time on every installation
• Large Hex Washer Head (0.930 in. head diameter) - the oversized integral washer head distributes load across a wider bearing area, removing the need for separate washers and simplifying your hardware requirements
• 3/8 in. hex drive - compatible with standard impact drivers and low-speed drills for fast, one-sided installation without the complexity of bolt and nut assemblies
• 3 in. thread length at 5 TPI - coarse thread pitch drives efficiently through dense structural timber and engineered wood, reducing installation effort while maintaining holding strength
• Single-side installation, no predrilling required - eliminates the time and cost of through-bolting setups, reducing installed cost compared to traditional HDG bolt, washer, and nut assemblies

Why This Product

• Eliminates costly bolt hardware - replaces traditional HDG bolt, washer, and nut assemblies with a single screw installed from one side, reducing both material costs and labor time on pile, pier, and dock projects
• Purpose-built for marine and coastal construction - the Hot-Dip Galvanized, Class C finish is specifically suited for saltwater-adjacent environments including structural pilings, boardwalks, and dock framing where corrosion is an ongoing concern
• No specialty drill bits required - the SawTooth self-drilling point means crews can start driving immediately without investing in auger bits or predrilling steps, keeping job sites moving efficiently
• Trusted Simpson Strong-Drive engineering - designed to meet the demands of structural wood-to-wood and engineered wood connections, delivering consistent performance in heavy-duty load-bearing applications

Specifications

• Brand: Simpson Strong-Tie
• Shank Diameter (in.): 0.276
• Length (in.): 4
• Head Type: Large Hex Washer Head
• Head Diameter (in.): 0.930
• Drive Type: 3/8 in. Hex
• Thread Type: Serrated Threads
• Thread Length (in.): 3
• TPI: 5
• Point Type: SawTooth Point
• Coating: Hot-Dip Galvanized, Class C
• Country of Origin: Taiwan

Available Pack Options

• SDWH27400G-RP1: 1 Ea
• SDWH27400GR30: 30 Pk - includes (1) driver bit
• SDWH27400GMB: 150 Pk - includes (2) driver bits
• SDWH27400G: 350 Pk - includes (2) driver bits

Approved Applications

• Structural pilings, piers, and dock framing
• Boardwalk construction
• Structural wood-to-wood connections
• Engineered wood connections
• Ledger connections
• Pile connections
• Marine and coastal construction environments

Install With

• For best results, use a minimum of 1/2 in. low-speed corded drill to install

Frequently Asked Questions

Does this screw require predrilling before installation?

No. The SawTooth point is a self-drilling tip that allows the screw to start and drive directly into structural timber without predrilling, saving labor time and eliminating the need for auger drill bits on pile and dock installations.

What coating does this screw have, and is it suitable for saltwater environments?

This screw features a Hot-Dip Galvanized, Class C coating, which provides a heavy-duty zinc layer specifically designed for use in marine, coastal, and other harsh outdoor environments including structural pilings, piers, and docks.

Can this screw replace traditional bolt, washer, and nut assemblies in pile connections?

Yes. The large integral hex washer head (0.930 in. diameter) eliminates the need for separate washers, and the single-side installation method removes the requirement for through-bolts and nuts - reducing installed cost and installation time compared to traditional HDG bolt assemblies.

What tool is recommended to drive this screw?

For best results, use a minimum of a 1/2 in. low-speed corded drill. The screw uses a 3/8 in. hex drive, which is compatible with standard hex-drive bits on corded drills and impact drivers that meet the recommended torque requirements for structural timber driving.