The Simpson Strong-Drive SDCP Timber-CP Screw (0.315 x 7", 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 to deliver superb holding power, this partially threaded timber screw pulls structural members tightly together with excellent load capacity - making it a trusted choice for engineered wood assemblies, multi-ply fastening, post frame construction, and factory-built or modular building projects. The yellow-zinc coating provides corrosion resistance suited for interior and dry-service environments, while the Type-17 point design typically eliminates the need for predrilling, saving time and labor on the job site.

Key Features

• Partial Thread Design (3-1/8" thread length) - draws structural members firmly together by allowing the unthreaded shank to pass freely through the near-side member, maximizing clamping force in timber-to-timber connections.
• Flat Head with Underhead Nibs (0.575" head diameter) - the nibs score the wood surface as the screw seats, allowing the large flat head to countersink cleanly and flush, producing a neat, professional finish without the need for a separate countersink bit.
• T40 6-Lobe Drive - provides a high-torque, low-cam-out interface that keeps the bit firmly engaged under heavy driving loads, reducing stripped drives and improving installation efficiency in dense timber materials.
• Type-17 Point - the self-cutting point bores into wood fibers to start the screw without predrilling in most applications, speeding up workflow and reducing material handling on mass-timber and general framing projects.
• Yellow-Zinc Coated Finish - delivers corrosion resistance appropriate for interior and dry-service applications, helping the fastener maintain its structural integrity over the life of the assembly.
• 0.315" outer diameter x 7" length - the substantial diameter and extended length provide deep thread engagement and strong axial load capacity suited for thick timber members, CLT panels, and structural composite lumber.
• 0.225" shank diameter - the reduced shank diameter relative to the thread OD minimizes wood splitting while the larger thread form maintains excellent withdrawal resistance in engineered and dimensional lumber.

Why This Product

• Engineered specifically for cross-laminated timber and mass-timber construction - this screw addresses the unique fastening demands of CLT panels, structural composite lumber, and multi-ply engineered wood assemblies where standard fasteners may lack sufficient load capacity or cause splitting.
• Predrilling is not typically required - the Type-17 point cuts cleanly into timber without a pilot hole, reducing tool changes and setup time on large-scale timber framing and modular construction projects.
• The partial thread and flat-head-with-nibs combination produces tight, flush connections - ideal for applications such as surface splines, lap joints, panel-to-beam, and ledger connections where both clamping strength and a clean surface appearance are required.
• Backed by Simpson Strong-Tie engineering for structural applications - the broad range of approved uses, from floor-to-floor fastening to general interior timber framing, means a single screw family can address multiple connection types across a project.

Specifications

• Brand: Simpson Strong-Tie
• Length: 7 in.
• Head Diameter: 0.575 in.
• Shank Diameter: 0.225 in.
• Thread Length: 3 1/8 in.
• Drive Type: T40 6-Lobe
• Head Type: Flat Head with Nibs
• 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

• SDCP22700-R50: 50 Pk - includes (1) T40, 6-lobe drive bit (replacement bit: BIT40T-134-R2)
• SDCP22700: 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 point is designed to self-start and cut into wood fibers, allowing the screw to be driven directly into timber and engineered wood members in most applications without a pilot hole.

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

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

What is the purpose of the partial thread design on this screw?

The partial thread - with a 3-1/8" threaded section on a 7" screw - is specifically designed to pull structural members together. The unthreaded shank passes freely through the near-side member while the threads bite into the far member, creating a strong clamping action that draws the two pieces tight. This is essential for CLT panel connections, lap joints, surface splines, and similar structural timber assemblies.

What tool bit is needed to drive this screw?

This screw uses a T40 6-Lobe (Torx-style) drive. A T40 driver bit is required for installation. The 6-lobe interface is designed to handle the high torque needed when driving large-diameter structural screws into dense timber and engineered wood materials while minimizing cam-out.

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