The Simpson Strong-Drive SDCP Timber-CP Screw is a heavy-duty structural fastener engineered for cross-laminated timber (CLT) and mass-timber construction, as well as general interior framing applications. Yellow-zinc coated for a clean, corrosion-resistant finish in dry-service environments, this 0.315-inch diameter, 11-inch partially threaded screw delivers superb holding power when pulling structural members together. The Type-17 point bites cleanly into dense wood fibers, typically without the need for predrilling, making it a practical and efficient choice for timber framers, modular construction crews, and structural wood joiners working with engineered lumber, structural composite lumber, and multi-ply assemblies.

Key Features

• Yellow-zinc coating - provides a corrosion-resistant finish suited for interior and dry-service structural applications, keeping fasteners looking clean and performing reliably over time.
• Flat head with underhead nibs (0.575 in. head diameter) - the nibs score the wood surface during installation, allowing the head to countersink flush and clean without surface tear-out or raised edges.
• T40 6-Lobe drive type - delivers high torque transfer with reduced cam-out risk, giving installers better control and efficiency when driving large structural screws into timber and engineered wood.
• Type-17 point - the aggressive self-drilling tip removes material as it drives, allowing the screw to penetrate dense CLT, LVL, and structural composite lumber in most cases without predrilling, saving time on the job.
• Partial thread design with 3-1/8 in. thread length - the unthreaded shank allows the screw to pull two structural members tightly together as the thread engages only the receiving member, creating a strong mechanical connection and excellent load capacity.
• 0.225 in. shank diameter with 0.315 in. overall diameter - the robust cross-section supports the high withdrawal and shear loads typical in mass-timber and CLT panel connections.
• 11-inch length - provides deep penetration into thick timber members, lap joints, ledger connections, and multi-ply engineered wood assemblies where shorter fasteners cannot reach full structural engagement.
• No predrilling typically required - reduces labor steps and tool requirements on site, speeding up installation across high-volume framing applications.

Why This Product

• Designed specifically for cross-laminated timber (CLT) and mass-timber construction - a fastener type purpose-built for the unique demands of modern engineered wood structures, where pulling force and flush seating matter most.
• The partial thread configuration actively clamps structural members together rather than simply penetrating them, making this screw a reliable choice for wood-to-wood connections, panel-to-beam joints, and floor-to-floor assemblies where tight contact is structurally critical.
• Available in a broad range of lengths from Simpson, so builders and framers working across diverse timber dimensions can select the right penetration depth for each specific joint or connection without over-specifying hardware.
• Suited for general interior and dry-service applications beyond mass timber - from post-frame and modular construction to structural composite lumber fastening - making it a versatile structural screw that handles multiple connection types on a single job site.

Specifications

• Brand: Simpson Strong-Tie
• Length: 11 in.
• Shank Diameter: 0.225 in.
• Head Diameter: 0.575 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
• Country of Origin: Taiwan

Available Pack Options

• SDCP221100-R50: 50 Pk - includes (1) T40, 6-lobe drive bit (replacement bit: BIT40T-134-R2)
• SDCP221100: 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

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

Predrilling is not typically required. The Type-17 point is designed to penetrate dense wood materials including CLT, structural composite lumber, and engineered wood without a pilot hole in most applications, reducing labor and setup time on site.

Why is this screw only partially threaded?

The partial thread design - with a 3-1/8 in. thread length on an 11 in. fastener - is intentional for structural pull-together connections. The unthreaded shank allows the screw to slide freely through the first member while the thread engages only the receiving member, pulling the two structural pieces tightly together with excellent clamping force and load capacity.

What drive bit does the SDCP Timber-CP screw require?

This screw requires a T40 6-Lobe (Torx-style) driver bit. The 6-lobe drive geometry allows high torque to be applied during installation with minimal cam-out, which is important when driving large-diameter structural screws into thick timber members.

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

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

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