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If you’ve ever watched standard lag bolts turn into rusty messes on a dock or beachside deck, you know the frustration. These 316 stainless steel hex head lag screws are built differently. Made from A4 marine grade stainless (316), they resist pitting and corrosion even in direct salt spray, chlorinated water, and acidic coastal environments — where A2 (304) screws fail within a season.
Manufactured to DIN571 standard, each lag screw features a coarse wood thread with a sharp point that bites deep into softwood and hardwood alike, and a hex head that accepts a standard wrench or socket for maximum torque. Available across four thread diameters — M6, M8, M10, and M12 — with lengths from 30mm to 200mm (approximately 1-3/16" to 7-7/8"). Pack quantities from 1 to 45 pieces to suit single repairs or full project builds.
Ideal for boat dock planking, seawall timber, coastal pergolas, marine-adjacent fencing, pool decking, and any outdoor wood structure where long-term corrosion resistance is non-negotiable.
Fasten dock planking, cleats, and structural timber with lag screws that won’t corrode in constant saltwater exposure — season after season.
Build or repair beachside decks, pergolas, fencing, and outdoor furniture that holds up to salt air, humidity, and coastal weather without rusting.
Stock multiple sizes for seawall repairs, boat lift hardware, and marine timber framing — the A4 grade meets the demands of professional marine construction.
Use around pools, spas, and chlorinated environments where standard stainless corrodes. The 316 grade resists chloride attack that destroys 304 hardware.
| Product Type | Hex Head Lag Screw / Coach Screw (Wood Lag Bolt) |
|---|---|
| Standard | DIN571 |
| Material | 316 Stainless Steel (A4 Marine Grade) |
| Grade | A4 (superior to A2/304 for saltwater and chloride environments) |
| Finish | Premium polished, natural stainless (solid alloy, not coated) |
| Head Style | Hex Head (External Hexagon) |
| Drive Style | Hex wrench / socket |
| Thread Type | Coarse wood thread with sharp point (DIN571) |
| Available Thread Diameters | M6, M8, M10, M12 |
| Available Lengths | M6: 30–120mm | M8: 30–200mm | M10: 40–200mm | M12: 60–200mm |
| Pack Options | 1, 2, 3, 4, 5, 6, 9, 10, 12, 15, 30, 45 pieces (varies by size) |
| System | Metric |
| Application | Timber, softwood, hardwood, pressure-treated lumber; marine, coastal, pool environments |
316 stainless contains molybdenum, which dramatically improves resistance to chlorides — including saltwater, pool chemicals, and coastal fog. 304 (A2) is suitable for mild outdoor use, but within a mile of the ocean or in direct salt spray, 316 (A4) is the only reliable choice. These marine grade lag screws won’t pit or rust after one season the way 304 hardware does.
For softwoods like cedar or pine, the sharp point and coarse thread often allow self-tapping. For hardwoods (teak, iroko, oak) or near the edge of any board, always drill a pilot hole approximately 80–90% of the screw diameter. For example, for an M6 lag screw, use a 5mm pilot bit. This prevents splitting and makes driving significantly easier.
Yes — that’s exactly what these are designed for. The A4 (316) composition is ideal for constant wet environments including freshwater and saltwater docks, boat lifts, and marine timber structures. Avoid using them below the waterline on aluminum trailers, as dissimilar metals in direct contact can cause galvanic corrosion.
A general rule: the lag screw should penetrate at least 1.5 times the thickness of the top material into the base timber. For example, if attaching a 20mm board to a post, select a length that gives you at least 30mm of thread engagement in the post. Thread diameter depends on load — M12 for heavy structural connections, M6–M8 for lighter framing and furniture.
No. Unlike coated or zinc-plated hardware, 316 stainless is a solid alloy throughout. A scratch won’t expose a different metal — the entire screw remains corrosion-resistant. This is one of the key advantages of solid stainless over surface-treated alternatives.
Yes. 316 stainless steel is the recommended fastener material for modern pressure-treated wood (ACQ, CA). The high copper content in treated lumber corrodes zinc-coated and even some 304 stainless fasteners over time. A4 (316) stainless holds up reliably in contact with treated timber.
DIN571 lag screws are designed to thread directly into wood — they have a wood thread, not a machine thread, and are not intended for use with standard metric nuts. If you need a through-bolt connection, use a standard M6/M8/M10/M12 hex bolt with machine thread instead. These lag screws are specifically for wood-to-wood or hardware-to-wood fastening.
