Whether you're building a sturdy deck, timber frame, or securing heavy outdoor structures, the GOOBETTER 4-inch lag screws (25-pack) deliver professional-grade holding power without the frustration of stripped heads or rust. Designed for contractors, woodworkers, and serious DIYers, these #14 x 4 structural wood screws eliminate breaking and slipping—thanks to the T30 Star drive and knurled shank that reduces torque and prevents wood from cracking. The advanced black coating withstands 1000 hours of salt spray testing, so you can trust them in rain, humidity, and coastal environments. Say goodbye to pre-drilling nightmares and hello to a flush, clean finish every time.
🔧 Key Features of 4 Inch Structural Lag Screws
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Anti-Corrosion Black Coating
Passed 1000-Hour Salt Spray Test – no coating failure. Provides an exceptional anti-rust barrier that ensures long-term durability even in harsh, humid, or coastal environments.
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T30 Star Drive + Knurled Shank
The star drive system eliminates bit slippage and cam-out, offering a safe and efficient fastening process. The knurled shank reduces torque required for drilling and prevents wood from cracking, even in dense hardwoods.
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Wide Application – Indoors & Outdoors
Ideal for deck building, log construction, timber framing, pole barns, fence installation, heavy shelving, and outdoor furniture. Works perfectly with pressure-treated lumber, hardwoods, and softwoods.
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Modified Truss Washer Head & Star Drive
The modified truss washer head sits flush against the surface, creating a clean and professional finish. Combined with the T30 drive, installation is quick, secure, and smooth.
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GOOBETTER Quality & Eco-Friendly Packaging
Each box includes 25 lag screws and 1 T30 star drive bit. Packaged in reusable, environmentally friendly materials that save storage space and reduce waste.
❓ Frequently Asked Questions – Heavy Duty Lag Screws
🔹 Do I need to pre-drill before installing these 4-inch lag screws?
Thanks to the specially designed knurled shank, these structural wood screws require less torque and significantly reduce wood splitting. For extremely dense hardwoods (like ipe or oak) or near the edge of the board, a small pilot hole is recommended—but for most softwoods and pressure-treated lumber, you can drive them directly. The star drive ensures smooth installation.
🔹 Will the black coating rust after months of outdoor exposure?
No. Our lag screws passed the strict 1000-hour salt spray test without coating failure. This means they offer superior rust and corrosion resistance, even in wet, humid, or coastal environments. Perfect for decks, garden structures, and exterior wood projects that face rain or snow.
🔹 What driver bit do I need? Is it included?
The screws use a T30 Star drive (torx style). Yes, each box comes with one T30 star drive bit — so you can start working right away. The star drive prevents cam-out and slipping, making the fastening process much safer than Phillips or hex heads.
🔹 Can I use these lag screws for pressure-treated lumber and ground contact?
Absolutely. These #14 x 4 structural screws are rated for exterior applications, including pressure-treated wood. The anti-corrosion black coating meets harsh condition requirements, and the washer head provides a tight hold. For projects like raised garden beds, deck substructures, or fence posts, these screws are an excellent choice.
🔹 Are these screws strong enough for load-bearing timber framing?
Yes, these heavy-duty construction screws are designed for structural applications. With #14 diameter, 4-inch length, and heat-treated carbon steel body, they provide exceptional shear and tensile strength. Ideal for attaching ledger boards, building pergolas, or any timber-to-timber connection that requires reliable holding power.
