The Simpson Strong-Drive SDCF TIMBER-CF Screw (0.315 in. diameter x 10-1/4 in. length) is a heavy-duty structural fastener engineered specifically for cross-laminated timber construction, mass timber assemblies, and general interior applications. Featuring a yellow-zinc coated, fully-threaded design with a proprietary unique point, this screw delivers fast starts and excellent withdrawal resistance - making it a reliable choice for demanding structural wood connections where performance cannot be compromised. The large flat head with underhead nibs countersinks cleanly into timber surfaces, resulting in a flush, professional finish without the need for additional prep work.

Key Features

• 0.315 in. shank and fully-threaded construction - delivers uncompromised structural strength and excellent withdrawal resistance throughout the full thread length of 9-3/4 in., maximizing holding power in mass timber and cross-laminated timber applications
• Yellow-zinc coating - provides corrosion protection suitable for interior and dry service environments, keeping the fastener performing reliably over the long term
• Flat head with underhead nibs - the 0.590 in. head diameter combined with the nibs allows for clean, controlled countersinking into timber surfaces without pre-drilling a recess, saving installation time
• T40 6-Lobe drive type - offers high torque transfer and reduced cam-out compared to traditional drive styles, giving installers better control and efficiency when driving into dense timber
• Proprietary unique point design - enables fast starts and self-penetration into wood, reducing the need for pre-drilling and speeding up workflow on mass timber job sites
• 10-1/4 in. overall length - sized to penetrate deeply into thick timber members, making this fastener well-suited for structural connections in CLT panels and heavy timber framing

Why This Product

• Designed from the ground up for cross-laminated timber and mass timber construction - a specialized fastener category that demands precise dimensional tolerances and high withdrawal resistance, both of which this screw is purpose-built to deliver
• The fully-threaded 9-3/4 in. thread length along a 10-1/4 in. screw body maximizes engagement in timber members, translating directly to stronger, more secure connections in structural framing and panel assemblies
• The self-starting proprietary point combined with the T40 6-Lobe drive reduces installation steps - no pilot hole required - which can meaningfully reduce labor time on large-scale mass timber projects
• Clean countersinking from the flat head with nibs results in flush installations without surface damage, making this screw a practical choice for exposed interior timber applications where finished appearance matters

Specifications

• Brand: Simpson Strong-Tie
• Coating: Yellow-Zinc Coated
• Finish: Yellow-Zinc Coated
• Length (in.): 10-1/4
• Shank Diameter (in.): 0.230
• Head Diameter (in.): 0.590
• Thread Length (in.): 9-3/4
• Head Type: Flat Head with Nibs
• Drive Type: T40 6-Lobe
• Country of Origin: Austria

Available Pack Options

• SDCF221014-R50: 50 Pk - includes one T40, 6-lobe driver bit (replacement bit: BIT40T-134-R2)
• SDCF221014: 250 Pk - includes two T40, 6-lobe driver bits (replacement bit: BIT40T-134-R2)

Approved Applications

• Cross-laminated timber (CLT) construction
• Mass timber construction
• General interior structural applications
• Interior and dry service environments only

Frequently Asked Questions

Is this screw suitable for outdoor or wet environments?

No. The Strong-Drive SDCF TIMBER-CF screw is designed for interior and dry applications only. It should not be used in exterior, wet, or high-humidity environments where moisture exposure is a concern.

Does this screw require pre-drilling before installation?

The proprietary unique point on this screw is designed to provide fast starts and self-penetration into wood, which means pre-drilling is generally not required for standard interior timber applications. This feature helps speed up installation in cross-laminated timber and mass timber assemblies.

What drive tool or bit is needed to install this screw?

This screw uses a T40 6-Lobe drive, so a T40 6-Lobe driver bit is required. The 6-Lobe drive geometry provides high torque transfer and minimizes cam-out, making it well suited for driving into dense timber members.

What makes this screw specifically designed for mass timber and CLT construction?

The 0.315 in. diameter structural body, 9-3/4 in. fully-threaded length, and large flat head with underhead nibs are all features tailored to cross-laminated timber and mass timber applications. The full thread engagement maximizes withdrawal resistance in thick timber members, while the flat head with nibs countersinks cleanly for flush, strong connections.