What Are Carriage Bolts? Key Features and Applications
A carriage bolt, also known as a coach bolt, plow bolt, or cup head bolt, is a heavy-duty, threaded fastener with a round head, square neck, and shallow dome shape. These bolts are valued for their strength and durability and are commonly used in wood applications, but can also fasten metal, plastic, or two pieces of wood together.
The Key Features of Carriage Bolts
Carriage bolts have a round head with a low, smooth dome. Beneath the head is a square neck. This neck fits into square holes or bites into wood or metal, preventing the bolt from turning when a nut is tightened on the opposite end. This feature allows for quick installation with one tool.Carriage bolts are made from strong materials such as stainless steel, zinc-plated steel, or galvanized steel. These materials resist corrosion and support high load-bearing applications. Because of this, carriage bolts are often used in construction, machinery, and outdoor projects.
Their shape and strength make carriage bolts a reliable fastener for joining wood, metal, or composite materials securely.
Applications of Carriage Bolts
Wood Applications
Carriage bolts are commonly used to build fences, decks, docks, and outdoor furniture. In these projects, the square neck of the bolt embeds into the wood as the nut is tightened. This prevents the bolt from turning and creates a secure hold. Stainless steel and galvanized options work well in marine and coastal areas where corrosion from saltwater is a concern.Metal Applications
In metal assemblies, the square neck fits into pre-cut square holes or slots. This design prevents the bolt from spinning during installation. Carriage bolts are often used in locks, hinges, and security hardware. They also appear in flatpack metal furniture and industrial racking, where a clean, smooth finish is needed on one side.Mixed-Material Applications
Carriage bolts are suitable for fastening wood to metal or joining two metal pieces. Their design provides a tight, reliable fit across different materials, making them useful in general construction, equipment assembly, and DIY projects.Find the Right Carriage Bolt for Your Next Project
Springs Fastener is your one-stop shop for fasteners of every type. Whether you need carriage bolts for wood, metal, or mixed-material assemblies, we carry reliable options in multiple sizes, materials, and finishes. Our inventory supports construction, manufacturing, and repair work across all industries.Explore our selection of carriage bolts: