Simpson Strong-Drive SDCP Timber-CP Screw, 0.315 x 9-1/2 in., T40 Drive, Yellow-Zinc Coated is a heavy-duty structural fastener engineered specifically for cross-laminated timber (CLT) and mass-timber construction, as well as general interior wood framing applications. Designed by Simpson Strong-Tie, this partially threaded screw delivers superb holding power and excellent load capacity, drawing structural members tightly together for dependable wood-to-wood connections. The yellow-zinc coating provides corrosion resistance suited to interior and dry-service environments, while the flat head with underhead nibs enables clean, flush countersinking without surface damage. Whether you are working on engineered wood assemblies, post-frame structures, or factory-built construction, this timber screw delivers the structural performance and installation efficiency that demanding projects require.

Key Features

• Partial threading (3-1/8 in. thread length on a 9-1/2 in. shank) - pulls structural members tightly together so connections are drawn closed with consistent clamping force, reducing gaps at the joint.
• Flat head with underhead nibs (0.575 in. head diameter) - the nibs seat the head cleanly into the wood surface, allowing flush countersinking without pre-chiseling or additional prep work.
• Type-17 cutting point - bores through timber fibers cleanly during installation, which means predrilling is not typically required, saving setup time on structural framing projects.
• T40 6-Lobe drive - provides a high-torque, cam-out-resistant engagement so installers can drive long screws through thick timber members with less slippage and fewer stripped drives.
• Yellow-zinc coating - offers corrosion resistance appropriate for interior and dry-service applications, protecting the fastener and maintaining holding strength over the life of the assembly.
• 0.315 in. major diameter / 0.225 in. shank diameter - the robust shank cross-section supports high structural loads in timber framing, engineered wood, and mass-timber connections.
• Designed for CLT and mass-timber construction - engineered to meet the performance demands of modern mass-timber building methods, including cross-laminated timber panels, structural composite lumber, and multi-ply engineered wood assemblies.

Why This Product

• Mass-timber and CLT projects demand fasteners that can handle thick cross-sections and high structural loads - this screw is purpose-built for those applications, covering panel-to-beam, panel-to-wall, and surface spline connections in a single fastener format.
• The Type-17 point eliminates the time-consuming predrilling step that other large-diameter screws typically require, keeping timber framing and general wood construction workflows moving efficiently.
• With a 9-1/2 in. length and partial threading, this fastener reaches deep into multi-ply or laminated assemblies while the threaded section concentrates clamping force exactly where the joint needs it most.
• The T40 6-Lobe drive system reduces cam-out risk during high-torque driving into dense timber, giving installers confident, consistent seating of the large flat head flush with the wood surface every time.

Specifications

• Brand: Simpson Strong-Tie
• Length: 9-1/2 in.
• Shank Diameter: 0.225 in.
• Head Diameter: 0.575 in.
• Thread Length: 3-1/8 in.
• Head Type: Flat Head with Nibs
• Drive Type: T40 6-Lobe
• Point Type: Type-17 Point
• Finish: Yellow-Zinc Coated
• Coating: Yellow-Zinc Coated
• Service Condition: Interior and dry-service applications
• Country of Origin: Taiwan

Available Pack Options

• SDCP22912-R50: 50 Pk - includes (1) T40, 6-lobe drive bit (replacement bit: BIT40T-134-R2)
• SDCP22912: 250 Pk - includes (2) T40, 6-lobe drive bits (replacement bit: BIT40T-134-R2)

Approved Applications

• Mass Timber / Cross-Laminated Timber (CLT)
• Engineered Wood
• Engineered Wood - Multi-Ply Fastening
• Structural Composite Lumber
• Fastening Wood-to-Wood
• Fastening Floor-to-Floor
• Timber Framing
• General Framing
• Framing - Wood
• Post Frame
• Factory-Built/Modular Construction
• Wood / Residential Construction

Frequently Asked Questions

Does this screw require predrilling before installation?

Predrilling is not typically required. The Type-17 cutting point is designed to bore into timber and engineered wood cleanly during driving, making it practical for cross-laminated timber, structural composite lumber, and general wood framing without the additional predrilling step.

Is this screw suitable for outdoor or pressure-treated lumber applications?

No. The yellow-zinc coating on this screw is rated for interior and dry-service applications only. It is not intended for outdoor, exposed, or pressure-treated lumber environments where a higher corrosion-resistant coating would be required.

What is the difference between the shank diameter and the listed screw size?

This screw has a major (thread) diameter of 0.315 in. and an unthreaded shank diameter of 0.225 in. The larger major diameter at the threads provides strong holding power in the wood, while the reduced shank allows the fastener to pull members together effectively - which is the key advantage of a partially threaded structural screw.

What drive bit is needed to install this screw?

This screw uses a T40 6-Lobe drive, which requires a T40 Torx-compatible bit. The 6-lobe interface is designed to support the high torque needed to drive a 9-1/2 in. structural screw into dense timber and engineered wood assemblies while minimizing cam-out.

Note: Product dimensions and/or thread length may differ from picture. Please see item description for specifications.