The Simpson Strong-Drive SDCF TIMBER-CF Screw (0.315 x 6-1/4") is a heavy-duty structural fastener engineered specifically for cross-laminated timber construction, mass timber assemblies, and general interior wood connections. Featuring a fully-threaded, yellow-zinc coated shank and a proprietary point geometry, this screw delivers fast starts, exceptional withdrawal resistance, and the structural integrity required for demanding timber-frame applications. Whether you are reinforcing beams, securing butt joists, or fastening wall-to-wall assemblies in mass timber projects, this screw provides the holding power and precision fit that professional builders rely on.

Key Features

• 0.315" Diameter Structural Shank - provides robust load-bearing capacity for demanding cross-laminated timber and mass timber applications where shear and withdrawal forces are significant.
• Flat Head with Underhead Nibs - the nibs bite into the wood surface as the head is driven, allowing for clean, flush countersinking without the need for pre-drilling a countersink recess.
• Fully Threaded at 5-7/8" Thread Length - maximizes thread engagement throughout the fastener's depth, delivering excellent withdrawal resistance across the full connection.
• Proprietary Unique Point - enables fast starts and reduces splitting in dense timber materials, saving time and improving accuracy during installation.
• T40 6-Lobe Drive - delivers high torque transfer with reduced cam-out, allowing the installer to drive these structural screws efficiently with a compatible T40 bit.
• Yellow-Zinc Coated Finish - protects the fastener during handling, storage, and installation in interior and dry-environment applications.
• 6-1/4" Overall Length - provides sufficient penetration depth for structural wood-to-wood connections in beam reinforcement, support beam fastening, and mass timber joinery.

Why This Product

• Designed from the ground up for cross-laminated timber (CLT) and mass timber construction - the 0.315" diameter shank and fully threaded body are sized to meet the structural demands of modern engineered wood systems where connection integrity is critical.
• The flat head with underhead nibs eliminates extra prep steps - the head countersinks cleanly on its own, reducing labor time and producing a professional flush finish in exposed or concealed timber connections.
• The proprietary point geometry provides fast starts in dense laminated timber, reducing installer effort and the risk of screw wander or material splitting during high-volume fastening operations.
• Versatile across a range of interior structural tasks - beam reinforcement, wall-to-wall fastening, support beam connections, and butt joist fastening - making this screw a reliable go-to for general interior mass timber work.

Specifications

• Brand: Simpson Strong-Tie
• Diameter: 0.315 in.
• Length: 6-1/4 in.
• Shank Diameter: 0.230 in.
• Head Diameter: 0.590 in.
• Thread Length: 5-7/8 in.
• Head Type: Flat Head with Nibs
• Drive Type: T40 6-Lobe
• Coating: Yellow-Zinc Coated
• Finish: Yellow-Zinc Coated
• Country of Origin: Austria

Available Pack Options

• SDCF22614-R50: 50 Pk - includes one T40, 6-lobe driver bit (replacement bit: BIT40T-134-R2)
• SDCF22614: 250 Pk - includes two T40, 6-lobe driver bits (replacement bit: BIT40T-134-R2)

Approved Applications

• Beam Reinforcement
• Fastening Wall-to-Wall
• Fastening Support Beams
• Fastening Butt Joists
• Mass Timber / Cross-Laminated Timber

Frequently Asked Questions

What drive bit is required for the SDCF TIMBER-CF screw?

This screw uses a T40 6-Lobe drive. A compatible T40 6-lobe driver bit is required for installation. The 6-lobe drive geometry allows high torque transfer and reduces cam-out, which is especially important when driving 0.315"-diameter structural screws into dense timber materials.

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

No. The Strong-Drive SDCF TIMBER-CF screw with yellow-zinc coating is designed for interior and dry applications only. It is not rated for exterior, wet-service, or pressure-treated lumber environments. For projects requiring outdoor or high-moisture performance, a different fastener with appropriate corrosion-resistant coating should be selected.

Does this screw require pre-drilling before installation?

The SDCF TIMBER-CF screw features a proprietary unique point designed to provide fast starts without pre-drilling in most timber applications. The flat head with underhead nibs also enables clean countersinking on its own, so a separate countersink operation is typically not required.

What types of timber construction is this screw designed for?

This structural fastener is specifically designed for cross-laminated timber (CLT) construction, mass timber construction, and general interior wood applications. Common uses include beam reinforcement, wall-to-wall fastening, support beam connections, and butt joist fastening where a strong, reliable structural connection is needed.