The Simpson Strong-Drive SDWH Timber-Hex Hot-Dip Galvanized Screw is a heavy-duty 0.276 in. diameter structural fastener engineered for demanding marine and coastal environments. Featuring a Class C hot-dip galvanized coating, this 12-inch timber screw delivers exceptional corrosion resistance in saltwater-exposed settings such as structural pilings, piers, docks, and boardwalks - offering a reliable, cost-effective alternative to traditional bolt, washer, and nut assemblies. The large hex washer head, serrated threads, and SawTooth point work together to pull structural wood members tight with no predrilling required, making installation faster and more straightforward on any pile connection job.

Key Features

• Hot-Dip Galvanized, Class C coating - provides heavy corrosion protection purpose-built for marine, coastal, and salt-air environments where standard coatings fall short
• 0.276 in. shank diameter with 12 in. length - delivers deep penetration and strong holding power in thick structural timber and pile connections
• SawTooth point - drives directly into wood without predrilling, saving time and eliminating the need for separate drill bits on the job site
• Large Hex Washer Head (0.930 in. diameter) - oversized integral washer distributes load evenly across the wood surface, eliminating the need to purchase and install separate washers
• 3/8 in. hex drive - compatible with standard impact drivers and low-speed corded drills for single-side installation, speeding up the overall workflow
• Serrated threads with 5 TPI and 3 in. thread length - aggressive thread geometry bites into timber securely, locking the connection even under dynamic load conditions like wave action and foot traffic
• Single-side installation required - no need to access both sides of the connection, which is a major advantage when working over water on docks and piers
• No separate hardware required - replaces costly bolt, washer, and nut assemblies, lowering total installed cost on pile and dock projects

Why This Product

• Designed specifically for structural pilings, piers, docks, and boardwalks - the Class C hot-dip galvanized coating stands up to the harsh, moisture-rich conditions these applications demand where lighter coatings would corrode prematurely
• Eliminates the need for predrilling, auger bits, separate washers, nuts, or bolts - reducing the number of components on the job and cutting installation time significantly compared to traditional fastening methods
• Single-side installation means the fastener can be driven from one face only, making it practical in tight or over-water locations where accessing both sides of a timber joint is impractical or impossible
• The large 0.930 in. diameter integral washer head and serrated thread design work together to create a secure, load-bearing wood-to-wood connection that holds up under the structural demands of pile and dock construction

Specifications

• Brand: Simpson Strong-Tie
• Shank Diameter (in.): 0.276
• Length (in.): 12
• 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

• SDWH271200G-RP1: 1 Ea
• SDWH271200GR30: 30 Pk - includes (1) driver bit
• SDWH271200GMB: 150 Pk - includes (2) driver bits

Approved Applications

• Structural pilings, piers, docks, and boardwalks in marine and coastal environments
• Structural wood-to-wood connections including pile connections and ledger connections
• Engineered wood structural applications requiring heavy-duty corrosion-resistant fasteners
• Replacement for 3/4 in. and 5/8 in. HDG bolt, washer, and nut assemblies in applicable pile connections

Install With

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

Frequently Asked Questions

Do I need to predrill before driving this screw into structural timber?

No predrilling is required. The SawTooth point is engineered to drive directly into structural wood, including piling material, without a pilot hole - eliminating the need for expensive auger drill bits and saving significant time on the job.

What type of drive tool is recommended for this screw?

The screw uses a 3/8 in. hex drive. For best results, Simpson recommends using a minimum of a 1/2 in. low-speed corded drill to ensure proper installation torque through the full 12 in. length.

Why is the Class C hot-dip galvanized coating specified for this screw?

Class C hot-dip galvanization provides a thick, metallurgically bonded zinc coating that is specifically suited for marine, coastal, and salt-air environments - applications where thinner galvanized or zinc-plated coatings would corrode rapidly and fail to provide long-term structural integrity in pile, pier, and dock connections.

Does this screw require a separate washer for structural installation?

No. The large hex washer head has an integral 0.930 in. diameter bearing surface that replaces a separate washer, distributing the load directly across the wood surface. This eliminates the need to source and install individual washers and reduces hardware cost on structural pile and dock projects.