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Deck builders, framers, and serious DIYers know the frustration of fasteners that strip, rust, or fail under load. These DIN571 zinc plated steel hex head lag screws deliver the clamping force and thread engagement you need for structural timber connections — without the stainless steel price tag.
Available in M6, M8, M10, and M12 thread diameters with lengths ranging from 20mm to 150mm (approximately 0.79" to 5.91"), each screw features a self-tapping wood thread that cuts its own path into softwood and hardwood alike. The hex head accepts standard sockets and wrenches for high-torque driving, and the zinc plating provides reliable corrosion protection for covered outdoor and indoor applications.
Ideal for deck ledger boards, fence post connections, timber framing, gate hardware, and heavy furniture assembly — wherever a standard wood screw simply isn't strong enough. Select your thread size and length above to match your specific load and material thickness.
Attach ledger boards, secure joist hangers, and connect structural timber members with M10 or M12 lag screws that won't back out under load or vibration.
Use M8 lag screws to mount hinges, secure rails to posts, and anchor gate hardware — strong enough for heavy wooden gates, easy to drive with an impact driver.
M6 lag screws are ideal for heavy furniture assembly, workbench construction, and shelving systems where a standard wood screw lacks the shear strength needed.
Secure wall-mounted brackets, anchor structural beams, and fasten timber cladding with confidence — these lag screws handle the jobs that regular screws can't.
| Type | Hex Head Lag Screw / Wood Coach Bolt |
|---|---|
| Standard | DIN571 |
| Material | Steel |
| Finish | Zinc Plated |
| Head Style | Hexagon (Hex) |
| Drive Style | Hex Socket / Wrench / Impact Driver |
| Thread Type | Self-Tapping Wood Thread |
| Thread Size | M6, M8, M10, M12 (see variant options) |
| Screw Length | 20mm – 150mm (see variant options) |
| Pack Quantity | 1, 3, 5, 10, 20, or 30 pieces (see variant options) |
| Application | Softwood, hardwood, engineered timber, structural lumber |
| Recommended Use | Decking, fencing, timber framing, gate hardware, furniture |
| Corrosion Resistance | Suitable for indoor and covered outdoor use |
Yes — pre-drilling is strongly recommended to prevent wood splitting and make driving easier. As a general guide, use a pilot bit approximately 70–80% of the bolt's core diameter: typically a 4.5mm bit for M6, 6mm for M8, 8mm for M10, and 10mm for M12. Drill depth should match or slightly exceed the screw length.
Zinc plating provides good corrosion resistance for covered outdoor environments such as porches, sheds, pergolas, and interior decking. For applications with direct rain exposure, ground contact, coastal salt air, or pressure-treated lumber (which can accelerate zinc corrosion), stainless steel lag screws are generally recommended for longer service life.
Lag screws (also called coach bolts or lag bolts) feature a hex head, a larger diameter shank, and coarser, deeper threads designed for heavy structural loads in timber. Regular wood screws have smaller heads and finer threads suited for lighter joinery. These DIN571 lag screws are intended for structural connections — ledger boards, post bases, beam-to-post joints — where standard screws would lack the shear and pull-out strength required.
As a general guide: M6 is typically used for light-duty furniture and shelving; M8 for fence rails, gate hinges, and medium timber connections; M10 for deck joists, beams, and structural brackets; M12 for heavy timber framing, log cabin construction, and high-load structural joints. The screw should typically penetrate the receiving member by at least 1.5 times the thickness of the top piece being fastened.
Yes. Use a hex shank socket adapter or a dedicated impact-rated hex socket that fits the head size — typically 10mm for M6, 13mm for M8, 17mm for M10, and 19mm for M12. An impact driver significantly speeds up installation, especially in dense hardwood. Always pre-drill to reduce driving resistance and prevent wood splitting.
The screw length should be chosen so that it penetrates the receiving timber member by at least the thickness of the top piece being fastened — and ideally more for structural connections. For example, when attaching a 38mm (1.5") board to a post, a screw of at least 80–100mm is typically appropriate. Longer screws provide greater pull-out resistance in structural applications.
Zinc plated fasteners can be used with some pressure-treated lumber, but the chemicals in modern ACQ and CA-treated wood can accelerate zinc corrosion over time. For long-term outdoor structural applications with pressure-treated timber, hot-dip galvanized or stainless steel lag screws are generally preferred. Check your local building codes for fastener requirements when working with treated lumber.
