#17×12″ CTX T-40 Bronze Construction Lag Screws

#17 x 12″ T-40 Construction Lag Screws

Built for Unmatched Strength and Reliability

Big Timber’s CTX™ #17 x 12″ Construction Lag Screws are the premium choice for builders tackling heavy-duty structural projects. With a heat-treated, hardened steel body and a triple-layer bronze coating, these lag screws are engineered to withstand the harshest conditions, providing exceptional holding power and longevity. Designed as the superior alternative to common lag screws, each screw features deep-cutting threads and a Type 17 tip for smooth, precise starts and reduced “walking”—no pre-drilling required.

Why Big Timber CTX™ Screws Stand Out

• Triple-Layer Corrosion Resistance
  Built to endure with a triple-coated bronze finish, these screws provide 1200-hour corrosion resistance in ACQ and salt spray conditions, ensuring durability for both interior and exterior use.
• Built-In Washer Head for Ultimate Holding Power
  Featuring a smooth-edged washer head, these lag screws offer increased pull-through strength and a professional finish. The six-lobe star drive minimizes cam-out and supports twice the torque of traditional Phillips or square drives, extending bit life.
• Precision Engineering with Aggressive Knurling
  Equipped with deep threads and an aggressive knurl, these screws enlarge the hole as they drive, reducing splitting and maximizing grip. Under-head cutting nibs allow for self-countersinking, giving you a clean, flush finish with every installation.

Ideal for Any Structural Challenge
From log construction to timber framing, laminated beams, ledger boards, and more, these heavy-duty lag screws are suited to high-stakes applications, including stair rails, deck posts, SIP panels, and pole barns. Certified to meet International Building Code and Residential Code standards, these screws have been independently tested for ultimate reliability (TER 1907-01).

Specifications & Available Sizes

• Available Quantities: 1 piece, 100 pieces, or 250 pieces
• Product Weight: Individual screws weigh .142lb; also available in 12lb and 35.7lb packaging
• Load Capacity: Engineered to handle 1,850 lbf (shear strength: 1,240 lbf) for 12″ T-40 screws, making them ideal for demanding applications

Big Timber Warranty
Big Timber guarantees these screws to be free from material and manufacturing defects. If a defect is found, the product will be replaced at no cost. Note: This warranty does not cover labor or installation-related costs.

Ready to take on any building challenge, Big Timber CTX™ lag screws provide the strength, durability, and performance that pros rely on.

CTX Standard Lag Screw Dimensions

Specifications