A2 Stainless Steel Carriage Bolts (Coach Bolts) — M3 M4 M5 M6 M8 M10 M12

Generally, add the total thickness of all materials being joined, then allow enough thread to fit a washer and nut — typically 6–12mm (about 1/4"–1/2") of thread should protrude beyond the nut. For example, joining two 20mm boards would typically call for a 50mm (≈2") bolt. When in doubt, size up rather than down.

For light-duty panel or furniture work, M6 or M8 is generally sufficient. For structural or load-bearing timber connections such as decking joists or gate posts, M10 or M12 is typically recommended. Always verify the load requirements for your specific application before selecting a size.

Yes. A2 stainless steel (304 grade) offers good corrosion resistance for most outdoor environments including garden furniture, decking, fencing, and playground equipment. For marine or coastal environments with heavy salt spray exposure, A4 (316) stainless is generally preferred for maximum corrosion resistance.

These bolts use standard ISO metric coarse thread conforming to DIN 603. They are compatible with any standard metric hex nut and flat washer of the matching diameter (e.g., an M8 carriage bolt takes an M8 nut). They are not compatible with UNC or UNF inch-thread hardware.

No special tools are required. The smooth domed head and square neck are designed to be seated flush into timber by hand or with a mallet. The square neck grips the material and prevents rotation while you tighten the nut from the opposite side using a standard wrench or socket set.

A2-70 grade stainless steel fasteners typically have a minimum tensile strength of 700 MPa (≈101,500 psi). Actual load capacity in your application depends on bolt diameter, thread engagement length, and the materials being joined. For critical structural applications, consult an engineer.

Yes. A2 stainless steel is generally compatible with most pressure-treated lumber. It resists the copper-based preservative chemicals used in treated wood far better than standard zinc-plated or hot-dip galvanized fasteners, making it a reliable choice for treated deck boards and fence posts.