What is a Coach Bolt?


Coach bolts are strong fasteners used for joining large pieces of timber. Unlike coach screws, which screw into wood, coach bolts need a nut to hold them in place. They are easily recognisable by the square section under the domed head, which locks into the timber to prevent spinning.


Also known as


Carriage bolts, cup-square hex, mushroom-head bolts and wood bolts.


Why use Coach Bolts?


Coach bolts are ideal for heavy-duty timber projects because they’re secure, tamper-proof, and leave a flat finish with no sharp corners. The square section locks in the wood, so you can tighten the nut with one hand without holding the bolt head. Their long threads make them suited for various applications.


Perfect for:



  • Landscaping projects like fencing and decking.

  • Roof trusses in construction and house-building.

  • Outdoor furniture, playground equipment and shelters.

  • Wooden packaging like strong crates and boxes.


Coach Bolts: How they work


Drill a pilot hole the same diameter as the bolt. Push the bolt through the timber and tap it into place with a hammer. Tighten the nut on the other side, pulling the bolt into the wood.


Use with Nyloc nuts and either penny washers or square repair washers.


Features and specifications



  • Sizes: M6, M8, M10 and M12 diameters. Lengths range from 20mm to 300mm. Use smaller sizes for thinner woods like plywood.

  • Material: Zinc-coated for corrosion resistance (our bestseller) or stainless steel.

  • Threading: Fully threaded up to 100mm with 100mm of thread for longer lengths.

  • Standard: Conforms to DIN603.

  • Includes: Nuts in every pack.


Need Coach Bolts for your project?


Get high-quality Unifix coach bolts from Fastco, with free delivery on orders over £30.*


Shop now on our website, email us at sales@fastco.co.uk, or call 01270 252326.


*Restrictions apply. Check our delivery page for details.