The Simpson Strong-Tie SDCFC TIMBER-CFC Screw is a heavy-duty structural fastener engineered for cross-laminated timber and mass timber construction, where thick, large-format structural members demand reliable, long-reaching fastening performance. Measuring 39-3/8 in. in length with a 0.390 in. overall diameter, this screw is built for interior structural connections including beam reinforcement, wall-to-wall and floor-to-floor connections, butt joints, and splitting prevention. The yellow zinc coating is formulated exclusively for dry, interior environments, making it a purpose-built solution for demanding timber assembly work where dimensional precision and joint integrity are critical.

Key Features

• Engineered for CLT and Mass Timber Applications - Designed specifically for cross-laminated timber and mass timber construction, this screw provides the structural holding power required when fastening large-format members that standard fasteners cannot adequately address.
• Extended 39-3/8 in. Length with 38 in. Thread Length - The long thread engagement spans deeply into thick timber assemblies, maximizing withdrawal resistance and joint strength across the full connection depth.
• T50 6-Lobe Drive System - The Torx-style drive geometry delivers superior bit engagement and dramatically reduces cam-out during installation, which is especially critical when driving a fastener of this length through dense timber materials.
• Cylinder Head Profile - The cylinder head sits flush and stable against the timber surface, providing a clean bearing surface without requiring a countersink and simplifying installation in structural panel and beam applications.
• Yellow Zinc Coating for Interior Use - Formulated exclusively for dry, interior environments, the yellow zinc finish provides consistent, reliable performance in protected structural applications without the added cost of exterior-rated coatings where they are not needed.
• Versatile Interior Structural Applications - Approved for use in beam reinforcement, support beam connections, butt joints, splitting prevention, and both wall-to-wall and floor-to-floor connections, covering a wide range of mass timber assembly needs with a single fastener specification.

Why This Product

• Purpose-Built for Modern Mass Timber Construction - As CLT and mass timber building methods continue to grow in use, having a fastener specifically rated and designed for these applications means structural connections meet the performance demands these assemblies require, without compromise.
• Exceptional Reach Through Thick Members - The 39-3/8 in. overall length and 38 in. thread length allow this screw to bridge connection points that shorter fasteners simply cannot reach, making it a practical solution for deep timber-to-timber joints and multi-layer panel assemblies.
• Reduced Installation Frustration at Scale - The T50 6-lobe drive system minimizes cam-out and driver slippage, which translates to faster, cleaner installation and less tool wear when driving long structural screws through dense CLT panels or glulam beams.
• Consistent Performance in Dry Structural Environments - The yellow zinc coating is matched to interior, dry-use conditions, ensuring the fastener performs as intended throughout the life of the structure without overspecifying for conditions that do not apply.

Specifications

• Specification: Value
• Model Number: SDCFC273938
• Length: 39-3/8"
• Shank Diameter: 0.29 in.
• Head Diameter: 0.525 in.
• Thread Length: 38"
• Head Type: Cylinder Head
• Drive Type: T50 6-Lobe
• Coating / Material: Yellow Zinc
• Pack Quantity: 50 per pack

Approved Applications

The SDCFC273938 TIMBER-CFC screw is designed for use in the following applications:

• Cross-laminated timber (CLT) construction
• Mass timber construction
• General