The Simpson Strong-Drive SDCP Timber-CP Screw with T40 6-Lobe drive and Yellow Zinc coating, offered by Simpson, is a structural fastener engineered specifically for cross-laminated timber (CLT) construction, mass timber projects, and general interior applications. Designed as a partially-threaded screw, it draws structural members tightly together with exceptional holding power - making it a reliable choice for timber framers, structural engineers, and contractors working on demanding wood-to-wood connections. The 0.390-inch overall diameter and 9-1/2-inch length provide deep penetration and strong clamping force, while the Yellow Zinc finish delivers corrosion resistance suited to interior structural environments.

Key Features

• Flat Head with Underhead Nibs - enables clean, flush countersinking into timber surfaces for a professional finish without pre-drilling a recess
• T40 6-Lobe Drive Type - provides high torque transfer with reduced cam-out, so installers can drive screws faster and with greater control in dense timber materials
• Type-17 Point - self-drilling tip bores into wood fibers cleanly, reducing splitting risk and eliminating the need for a pilot hole in many timber applications
• Partial Thread Design (3-1/8-inch thread length) - the unthreaded shank pulls members together rather than binding in the near-side piece, creating tight, gap-free connections between structural panels and beams
• 0.275-inch Shank Diameter - a robust shank cross-section delivers high shear and withdrawal capacity suited to structural timber connections
• 0.7-inch Head Diameter - wide bearing surface distributes load across the timber face, reducing the chance of pull-through in panel and plate connections
• Yellow Zinc Coating - provides corrosion resistance for interior structural applications, helping maintain long-term fastener integrity in protected environments
• 9-1/2-inch Length - deep reach allows secure fastening through thick CLT panels, mass timber members, and multi-layer assemblies without supplemental hardware

Why This Product

• Purpose-built for cross-laminated timber and mass timber construction - this screw addresses the specific demands of CLT panel-to-panel and panel-to-beam connections where conventional screws lack the length, shank strength, or thread geometry to perform reliably
• The partial thread design solves a common problem in timber framing: standard fully-threaded screws can hold in the near-side member and prevent joint closure, while this fastener's unthreaded shank allows members to pull together tightly for a rigid, gap-free connection
• The T40 6-Lobe drive combined with the Type-17 self-drilling point reduces installation steps - no pre-drilling required in many applications - saving time on large timber framing projects where hundreds of fasteners may be installed
• The large flat head with nibs countersinks cleanly into timber surfaces, making this screw well-suited for surface splines, lap joints, and ledger connections where a flush fastener head is required for adjacent member fit-up

Specifications

• Brand: Simpson Strong-Tie
• Length: 9-1/2 in.
• Shank Diameter: 0.275 in.
• Overall Diameter: 0.390 in.
• Head Diameter: 0.7 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
• Application: Cross-laminated timber construction, mass timber construction, general interior applications
• Sold As: Pack

Available Pack Options

• SDCP27912-R30: 30 Pk
• SDCP27912: 250 Pk

Approved Applications

• Wall to wall connections
• Floor to floor connections
• Wall to floor connections
• Panel to beam connections
• Panel to wall connections
• Surface splines
• Lap joints
• Ledger connections
• General timber framing

Frequently Asked Questions

Why is a partially-threaded screw recommended for timber-to-timber connections?

A partial thread design allows the unthreaded shank to pass freely through the near-side member while the threads engage only in the far-side member. This pulls the two pieces tightly together rather than binding both sides, resulting in a rigid, gap-free connection - which is why this screw is specifically engineered for cross-laminated timber and mass timber assemblies.

Does this screw require a pilot hole before installation?

The Type-17 self-drilling point is designed to bore into wood fibers without a pilot hole in many timber applications, reducing installation steps and saving time. For very dense timber species or when working near the end grain, a pilot hole may help reduce splitting risk - but in typical CLT and mass timber applications the Type-17 point handles entry on its own.

What is the advantage of the T40 6-Lobe drive over a standard hex or Phillips drive?

The T40 6-Lobe (Torx-style) drive engages the bit across six contact points rather than four or two, which significantly increases torque transfer and reduces cam-out. This matters in structural timber applications where high installation torque is needed to seat the screw fully and pull members together - and where cam-out can damage the drive recess and slow the job down.

What does the Yellow Zinc coating protect against?

The Yellow Zinc finish provides corrosion resistance suited to interior structural environments. It is designed for use in cross-laminated timber construction, mass timber construction, and general interior applications where the fastener will be protected from direct weather exposure but still benefits from a corrosion-resistant coating for long-term performance.

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