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Big Dog ZFmax C4 Wood Screw 10x120mm T40 25pcs Fast 281537

Heavy-duty structural timber screw with wide washer head, cutter tip and C4 ZFmax coating for outdoor wood construction joints.

Big Dog ZFmax C4 Wood Screw 10x120mm T40 25pcs Fast 281537

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Big Dog ZFmax C4 Wood Screw 10x120mm T40 25pcs Fast 281537

Heavy-duty structural timber screw with wide washer head, cutter tip and C4 ZFmax coating for outdoor wood construction joints.

Description

The Fast Big Dog 10x120mm, with a C4 corrosion resistance rating, is a technically advanced structural screw designed for heavy-duty timber connections in outdoor environments. It is engineered to serve as a direct replacement for traditional lag screws, offering significantly faster installation without compromising mechanical load-bearing capacity. The combination of a precision-engineered thread geometry, milling features, and a robust, oversized head ensures tight clamping and maximum stability in heavy timber.

Structural Stability and Load Distribution

The screw’s integrated washer head provides a broad contact surface against the timber, distributing clamping forces over a significantly larger area than traditional countersunk heads. This geometry effectively prevents the screw head from sinking too deep or crushing the wood fibers during tightening, resulting in exceptionally high pull-through resistance. In load-bearing structures subject to movement and dynamic loads, the generously sized head ensures that the connection maintains its rigidity and remains completely free of play over a long period.

Well-conceived shank design and thread geometry

The design features a partially threaded shank, with a 90 mm threaded section combined with a 30 mm unthreaded (smooth) portion beneath the head. As the threads engage with the inner timber member, the smooth section slides freely through the outer member, generating a mechanical pulling force that draws the timber components tightly together. The screw tip is equipped with an integrated cutting edge that cleanly severs the wood fibers upon entry. Positioned immediately above the threads is an efficient shank cutter (reamer) that enlarges the pilot hole along the shank. This design detail significantly reduces friction, lowers the required driving torque, and conserves valuable battery power during extensive fastening work.

Advanced corrosion protection for outdoor use

To withstand moisture and harsh weather conditions, the fastener is treated with ZFmax—a surface coating certified for corrosivity category C4. This coating forms a robust barrier that protects against rust, even during prolonged outdoor exposure to precipitation, temperature fluctuations, and humid environments. The finish preserves the screw’s structural integrity, ensuring a reliable connection under demanding conditions.

Verified standards and approvals

The fastener complies with stringent European and national safety requirements for load-bearing structural components. The product is CE-marked in accordance with the harmonized standard EN 14592, which certifies its declared strength values for use in timber structures. Further assurance is provided by the type-approval certificate SITAC 0044/07, confirming that the screw has been tested and approved for professional structural construction.

Primary applications

This heavy-duty timber screw is specifically designed for joining bearers, glulam beams, roof trusses, structural studs, and posts. Typical applications include the construction of decks, patios, carports, pergolas, canopies, and other heavy-duty outdoor timber frameworks where high tensile strength and load-bearing capacity are required.

Drive type and installation

Installation is performed using a TX40 drive bit. The deep Torx recess ensures an optimal grip, eliminating the risk of cam-out, minimizing wear on the bit, and allowing for high torque transmission. The fastener can be easily driven into place using a powerful cordless drill/driver or an impact driver equipped with the appropriate bit.

Technical Specifications

  • Product Series: Big Dog
  • Dimensions: 10x120 mm
  • Threading: Partially threaded
  • Total screw length: 120 mm
  • Threaded section: 90 mm
  • Head type: Large washer head
  • Drive type: TX40
  • Point type: Cutting point
  • Shank feature: Integrated shank cutter
  • Surface coating: ZFmax
  • Environmental class: Corrosivity class C4
  • European standard: CE-marked according to EN14592
  • Certification: SITAC type-approval certificate 0044/07
  • Package size: 25 pieces per package

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