The Simpson Strong-Drive SDCP Timber-CP screw in 0.315 x 6-1/4" is a heavy-duty structural fastener engineered for cross-laminated timber (CLT) and mass-timber construction, as well as general interior and dry-service applications. Featuring a partially threaded shank and a Type-17 cutting point, this yellow-zinc coated screw pulls structural members together with superb holding power and excellent load capacity - making it a reliable choice for timber framing, engineered wood assemblies, and wood-to-wood fastening. The large flat head with underhead nibs countersinks cleanly and flush with the surface, while the T40 6-Lobe drive delivers high torque transfer without cam-out. Predrilling is typically not required, saving time on the job site.

Key Features

• Partially threaded shank with 3-1/8" thread length - draws structural members tightly together for strong, rigid connections in timber and mass-timber assemblies
• Type-17 cutting point - self-starting design reduces the need for predrilling, speeding up installation across a wide range of wood substrates
• T40 6-Lobe drive - maximizes torque transfer and reduces driver slippage, providing better control and efficiency during installation
• Flat head with underhead nibs (0.575" head diameter) - nibs shear cleanly into the wood surface, allowing the head to sit flush without additional countersinking tools
• Yellow-zinc coating - provides corrosion resistance suitable for interior and dry-service environments, protecting fastener integrity over time
• 0.225" shank diameter at 6-1/4" length - delivers structural shear and withdrawal performance appropriate for heavy timber and multi-ply engineered wood connections

Why This Product

• Designed specifically for cross-laminated timber (CLT) and mass-timber construction - a growing application category that demands fasteners with verified structural performance, not standard wood screws
• The partially threaded design concentrates clamping force between members rather than threading through both, which is critical when fastening multi-ply panels, floor-to-floor connections, or surface splines where joint tightness directly affects structural integrity
• No predrilling is typically required, which reduces setup time and labor costs on timber framing and factory-built or modular construction projects where repetitive fastening cycles add up quickly
• The broad range of available lengths in the SDCP series means this same driver bit and installation method can be used across multiple connection types - from general framing and post frame to structural composite lumber and ledger connections - keeping your workflow consistent

Specifications

• Brand: Simpson Strong-Tie
• Length: 6-1/4 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
• Country of Origin: Taiwan

Available Pack Options

• SDCP22614-R50: 50 Pk - includes (1) T40, 6-lobe drive bit (replacement bit: BIT40T-134-R2)
• SDCP22614: 250 Pk - includes (2) T40, 6-lobe drive bits (replacement bit: BIT40T-134-R2)

Approved Applications

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

Frequently Asked Questions

Do I need to predrill before installing the SDCP Timber-CP screw?

Predrilling is not typically required. The Type-17 cutting point is designed to self-start in wood substrates, including engineered wood and cross-laminated timber, reducing installation steps and saving time on the job site.

What drive bit is needed for this screw?

This screw uses a T40 6-Lobe drive. Using the correct T40 bit is important for achieving proper torque transfer and avoiding cam-out, especially when driving into dense timber or multi-ply engineered wood panels.

Why is this screw only partially threaded, and what difference does that make?

The partial thread design - with a 3-1/8" threaded section on a 6-1/4" screw - means the threads engage only the receiving member while the smooth shank passes through the leading member. This pulls the two pieces tightly together under clamping force, which is critical for structural connections in mass timber, CLT panels, and multi-ply fastening applications.

Is this screw suitable for outdoor or wet-service applications?

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

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