What is a carriage bolt?

A carriage bolt is a type of fastener that features a round head and a square shoulder beneath the head that prevents it from turning when tightened. They are typically used in wood-to-metal or wood-to-wood connections where a smooth, finished appearance is desired on the exposed side. Carriage bolts are commonly used in applications such as decks, docks, fences, and furniture assembly.

Carriage bolts come in a variety of sizes and materials, including stainless steel, galvanized steel, and zinc-plated steel. They are available in both standard and metric sizes, with the most common diameters ranging from 1/4 inch to 1 inch.

When installing a carriage bolt, it is important to use a washer and nut on the opposite side to secure the bolt in place. The square shoulder beneath the head of the bolt should be hammered into a pre-drilled hole to prevent the bolt from spinning during tightening.

Overall, carriage bolts are a reliable and versatile fastener option for a wide range of construction and woodworking projects.