SG TZH 5/16" x 4" Hex Head Lag Screws 20-Pack — 304 Stainless Steel, Partial Thread for Heavy Wood & Decking

These are 5/16" x 4" hex-head lag screws made from 304 (18-8) stainless steel—durable, corrosion-resistant fasteners for heavy wood and structural connections.

Built for outdoor and demanding indoor projects, the SG TZH lag bolts combine thicker hex heads for wrench-driven torque with a partial-thread shank that draws timber tightly together. Their 304 stainless composition resists rust and maintains strength in humid or coastal environments. Each pack contains 20 pieces sized for common decking, beam attachment and heavy carpentry tasks.

How do these lag screws perform in exterior projects?

Thanks to 18-8 (304) stainless steel, these lag screws stand up well to moisture and many corrosive conditions, extending the life of exterior assemblies. The coarse threads bite into wood for a secure hold while the partial-thread shank pulls pieces flush without binding.

• Material: 304 stainless steel for improved corrosion resistance
• Threading: partial thread to clamp lumber tightly
• Head style: hexagon head for high-torque driving with a wrench or socket
• Quantity: 20 screws per package for small-to-medium projects

What sizes and driving tools are needed?

Each screw measures 5/16" in diameter and 4" in overall length, with a recommended wrench/socket size of 1/2" for the hex head. You can drive them with a ratchet, impact driver with a hex socket, or a breaker bar for the highest torque needs.

• Diameter: 5/16" (suitable for heavy timber connections)
• Length: 4" for substantial depth into beams or posts
• Wrench size: 1/2" hex socket or wrench
• Tools: ratchet, impact driver with socket adapter, or torque wrench

How should I prepare wood and pilot holes for these lag bolts?

Drilling a pilot hole reduces splitting and ensures proper engagement of the screw threads—especially near edges or in hardwoods. The pilot hole size depends on wood density: use a slightly smaller bit for softwoods and a bit closer to the screw core diameter for hardwoods.

• Softwood pilot: use a slightly smaller bit than the screw shank
• Hardwood pilot: match pilot to the screw’s core (minor) diameter
• Tip: countersink or chamfer entry to seat the hex head flush
• Use lubricant or wax on long drives to reduce friction

Will these lag screws work with metal connectors and brackets?

Yes—these hex head lag screws are compatible with many metal ties, timber brackets and post bases. Their hex head offers stronger torque application for driven connections where clamp force and shear capacity matter.

• Compatible with common timber connectors and post bases
• Hex head allows higher torque without cam-out than hex-washer-head fasteners
• Partial thread design leaves unthreaded shank to act as shear-bearing surface
• 304 stainless reduces risk of galvanic corrosion with stainless or coated brackets

Who is this for: Builders, deck contractors, and serious DIYers who need rugged, weather-resistant fasteners for structural woodwork will appreciate these SG TZH 5/16" x 4" lag screws. They suit jobs that demand high clamping force and reliable corrosion resistance—deck framing, pergola and post anchoring, heavy cabinetry, or any project connecting large timber members.