The Simpson Strong-Drive SDWH TIMBER-HEX Stainless Steel Screw is a structural hex-head fastener engineered as a direct replacement for traditional lag screws in demanding wood-framing applications. Built from Type 316 stainless steel, this 0.185" diameter by 4" long screw delivers exceptional corrosion resistance in harsh outdoor environments, coastal exposures, and chemically treated lumber - without the time-consuming predrilling that lag screws typically require. Designed to meet 2018 and 2021 IRC and IBC code requirements, this fastener gives builders and contractors a code-compliant, high-strength solution that installs faster and more reliably than conventional hardware.

Key Features

• Type 316 stainless steel material and finish - provides superior resistance to corrosion, saltwater exposure, and harsh outdoor conditions, making it ideal for coastal builds, wet environments, and pressure-treated lumber applications where standard fasteners would degrade prematurely.
• No predrilling required in most applications - the sharp point and box thread design allow direct installation into wood framing, significantly reducing labor time and tool requirements compared to traditional lag screw installation.
• Unique "box" thread design with raised-ridge technology - reduces driving torque during installation, meaning less strain on the installer and the driving tool while achieving secure structural engagement.
• 5/16 in. hex drive with hex washer head (0.455 in. head diameter) - the large bearing area of the hex washer head distributes load across the fastening surface, improving pull-through resistance and connection integrity.
• Sharp point tip - starts cleanly without wandering, enabling precise placement and faster entry into framing lumber with no pilot hole needed.
• 2-3/8 in. thread length - engineered to deliver strong thread engagement in the receiving member for reliable, code-compliant structural connections.
• Meets 2018 and 2021 IRC and IBC code requirements - gives contractors and inspectors confidence that the fastener satisfies current building code standards for common wood-framing applications, simplifying the inspection and approval process.
• Driver bit included - ready to use right out of the package, reducing the need to source additional tooling before beginning work.

Why This Product

• Eliminates predrilling on most installations - traditional lag screws demand pilot holes, adding steps and time to every connection. This screw's sharp point and box thread geometry drive directly into structural lumber, cutting installation time and streamlining workflow on framing jobs.
• Type 316 stainless steel stands up where other fasteners fail - Grade 316 alloy offers a higher level of corrosion protection than standard stainless options, making this screw the appropriate choice for exterior decking, dock framing, ledger boards, and any application exposed to moisture, salt air, or treated wood chemicals.
• Engineered for lag-screw replacement with structural confidence - this fastener is specifically designed and code-listed to substitute for lag screws in several common framing connections under 2018 and 2021 IRC and IBC requirements, so you get a modern structural solution without sacrificing code compliance.
• Hex washer head provides a large bearing surface - the 0.455 in. head diameter spreads clamping force effectively, reducing the risk of head pull-through and improving the overall integrity of wood-to-wood structural connections such as ledger applications.

Specifications

• Brand: Simpson Strong-Tie
• Material: Type 316 Stainless Steel
• Finish: Type 316 Stainless Steel
• Length: 4 in.
• Shank Diameter: 0.185 in.
• Head Type: Hex Washer Head
• Head Diameter: 0.455 in.
• Drive Type: 5/16 in. Hex
• Thread Type: Box Threads
• Thread Length: 2 3/8 in.
• Point Type: Sharp Point
• Country of Origin: Taiwan

Available Pack Options

• SDWH19400SS-R20: 20 Pk - includes (1) driver bit
• SDWH19400SS-R100: 100 Pk - includes (1) driver bit

Frequently Asked Questions

Do I need to predrill before installing this screw?

No predrilling is necessary in most applications. The sharp point and box thread design allow this structural screw to drive directly into wood framing lumber, saving time and eliminating an extra step compared to traditional lag screw installation.

Why is Type 316 stainless steel important for this type of fastener?

Type 316 stainless steel offers a high level of corrosion resistance, making it well suited for exterior structural connections, ledger board applications, coastal environments, and installations involving pressure-treated lumber or other materials that can accelerate corrosion in lesser-grade fasteners.

Is this screw approved for use in code-required structural applications?

Yes. This fastener meets 2018 and 2021 IRC and IBC code requirements for several common wood-framing applications, making it suitable for use on projects subject to building inspections and standard residential or commercial framing codes.

What drive tool does this screw require?

This screw uses a 5/16 in. hex drive. A driver bit is included with the product so you can begin installation without sourcing additional tooling. A standard hex-drive impact driver or drill is recommended for structural installations.

Note: Product dimensions and/or thread length may differ from picture.