The Simpson Strong-Drive SDWS TIMBER Screw in Type 316 Stainless Steel (0.275" shank diameter x 5" length) is a heavy-duty structural wood fastener engineered by Simpson as a high-strength, easy-to-install alternative to traditional lag screws and through-bolting. Built from severe-corrosion-resistant Type 316 Stainless Steel, this screw is purpose-built for demanding outdoor, coastal, and marine environments where exposure to saltwater, salt air, and moisture would quickly compromise standard fasteners. Whether you are a professional contractor framing a dock or a DIYer restoring a boardwalk, this timber screw delivers the structural integrity and corrosion resistance the job demands - and it is code listed under IAPMO UES ER-192, meeting 2018 and 2021 IRC and IBC code requirements for several common wood framing and engineered-wood applications.

Key Features

• Type 316 Stainless Steel material - provides severe corrosion resistance in saltwater, coastal salt-air, and chemically aggressive environments where standard zinc-plated or even Type 304 stainless fasteners may degrade over time.
• 0.275" heavy-duty shank diameter - delivers high shear and withdrawal strength comparable to traditional lag screws and through-bolts, making it suitable for structural wood-to-wood connections without the need for pre-drilling bolt holes.
• 5" length with 3" thread engagement - provides deep, secure thread bite into the receiving member, maximizing holding power in heavy timber and engineered-wood assemblies.
• SawTooth point - self-starting tip cuts through wood fibers cleanly, reducing installation effort and virtually eliminating the need for pre-drilling in most applications.
• Washer head (0.650" head diameter) - the wide bearing surface distributes load across the wood face, reducing surface crushing and providing a clean, professional finish.
• T50 6-Lobe drive - delivers high torque transfer with reduced cam-out compared to hex or square drives, allowing faster, more confident installation with a standard T50 bit.
• Code listed under IAPMO UES ER-192 - meets 2018 and 2021 IRC and IBC requirements for several common wood framing and engineered-wood applications, giving contractors and inspectors the documentation they need on the job.
• 5 TPI (threads per inch) thread pitch - aggressive thread profile optimized for structural timber, maximizing withdrawal resistance in both solid lumber and engineered-wood products.

Why This Product

• Built specifically for coastal and marine construction - Type 316 Stainless Steel is the recognized standard material for fasteners in pier, dock, boardwalk, and wharf applications where continuous salt-air or direct saltwater exposure would corrode lesser materials, causing structural failure over time.
• Eliminates the complexity of traditional through-bolting - the SDWS TIMBER screw installs with a T50 driver bit and no through-hole layout or bolt hardware, drastically reducing installation time and labor cost compared to conventional lag screw or through-bolt methods.
• Engineered for mass timber and cross-laminated timber (CLT) connections - the SawTooth point and structural shank diameter make this screw a reliable fastener for modern mass timber framing assemblies where code-compliant, corrosion-resistant connections are required.
• Suitable for both professional and DIY applications - with its self-starting point, standard 6-lobe drive, and code-listed performance data, this screw reduces the technical barrier for structural timber connections on projects ranging from commercial piers to residential dock and boardwalk restorations.

Specifications

• Brand: Simpson Strong-Tie
• Material: Type 316 Stainless Steel
• Finish: Type 316 Stainless Steel
• Length (in.): 5
• Shank Diameter (in.): 0.275
• Thread Length (in.): 3
• TPI: 5
• Head Diameter (in.): 0.650
• Head Type: Washer Head
• Drive Type: T50 6-Lobe
• Point Type: SawTooth Point
• Code Listing: IAPMO UES ER-192
• Code Compliance: Meets 2018 and 2021 IRC and IBC requirements for several common wood framing and engineered-wood applications

Available Pack Options

• SDWS27500SS-RC10: 10 Pk - includes one 6-lobe, T-50 driver bit
• SDWS27500SS-R30: 30 Pk - includes one 6-lobe, T-50 driver bit
• SDWS27500SS: 300 Pk - includes two 6-lobe, T-50 driver bits

Approved Applications

• Fastening Wood-to-Wood
• Corrosive Environments
• Marine Construction
• Pier Restoration
• Dock and Boardwalk
• Mass Timber / Cross-Laminated Timber
• Coastal / Salt Air Environments

Frequently Asked Questions

Does this screw require pre-drilling before installation?

In most structural timber applications, pre-drilling is not required thanks to the SawTooth point, which self-starts and cuts through wood fibers to allow direct installation. This significantly speeds up the installation process compared to traditional lag screws that typically require pilot holes.

Why is Type 316 Stainless Steel specified for marine and coastal fastener applications?

Type 316 Stainless Steel contains molybdenum, which provides a higher level of corrosion resistance than Type 304 stainless, making it the material of choice for environments with direct saltwater contact, salt-air exposure, and other chemically aggressive conditions - such as docks, piers, boardwalks, and wharves.

What drive tool is needed to install this screw?

This screw uses a T50 6-Lobe (Torx-style) drive, which requires a T50 driver bit. The 6-lobe interface provides high torque transfer with minimal cam-out, allowing the structural shank to be driven fully into heavy timber without stripping the drive recess.

Is this screw code approved for structural framing applications?

Yes. The Strong-Drive SDWS TIMBER screw is code listed under IAPMO UES ER-192 and meets the 2018 and 2021 IRC and IBC code requirements for several common wood framing and engineered-wood applications, providing the code compliance documentation contractors and building inspectors require on permitted structural projects.

Note: Product dimensions and/or thread length may differ from picture. Please see the specifications above for exact dimensions.