Coach Bolts

Often called carriage bolts or cup square hex bolts, coach bolts have a domed head with a square underside. Our range of coach bolts that are zinc plated come with a hex nut. For stainless steel coach bolts, you must order the nuts separately.

Carriage bolts are available in a range of sizes with metric coarse threads. They are most commonly used in the construction and timber trades.

Coach bolts are often confused with coach screws, which are actually hexagon-headed woodscrews. Coach bolts are commonly crafted from mild steel in strength grades 4.6 or 4.8. Our stock of BZP bolts is usually marked with the manufacturer's identification and the strength grade on the head.

What Are Coach Bolts Used For?

Coach bolts are most commonly used for joining different materials together such as metal to wood. They are often seen as a heavy-duty fastener as they can be used at crucial structural joins. However, that is not to say that they can't be used for a wide variety of DIY applications. Their large domed head helps to provide a secure fixing.

The name "carriage bolt" dates back to when horse-drawn carriages were used. These bolts were used to fix metal straps to wooden parts. The square head held the bolt tight as the nut was tightened.

Please note: All coach bolts up to 100mm length are fully threaded. For those over 100mm, thread length can vary depending on the manufacturer, so some products may not be fully threaded. Please feel free to check with us before placing your order to confirm thread length.