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When To Use Carriage Bolt

Pulished on May. 10, 2024

Carriage bolts are a type of fastener known for their unique design and versatile applications. They are easily recognizable by their round, domed heads and square necks directly under the head. This construction makes them particularly useful in various woodworking and metalworking projects. Understanding when to use a carriage bolt can ensure the structural integrity and aesthetic quality of your projects.

Carriage bolts

Characteristics of Carriage Bolts

Carriage bolts are distinct due to several key features that make them suitable for specific applications:

Round, Domed Head: The smooth, rounded head provides a finished appearance and prevents tampering from the head side once installed.

Square Neck: The square section under the head allows the bolt to grip into the material, preventing it from turning when a nut is tightened on the other end.

Thread Length: Carriage bolts typically have a fully threaded or partially threaded shank, depending on their length and the requirements of the application.

Applications in Woodworking

Carriage bolts are commonly used in woodworking projects due to their ability to create a secure and aesthetically pleasing connection.

Deck Construction: In building decks, carriage bolts are often used to fasten wooden beams and posts. Their domed heads provide a smooth surface, reducing the risk of injury, while the square neck grips the wood, preventing the bolt from spinning.

Furniture Assembly: Carriage bolts are ideal for assembling furniture, such as tables and chairs. The rounded head provides a clean look, and the bolt can be securely tightened without damaging the wood.

Fence Building: When constructing wooden fences, carriage bolts offer a strong and durable connection. The bolts can hold the rails and posts together tightly, ensuring the fence's stability and longevity.

Applications in Metalworking

While commonly used in woodworking, carriage bolts also have applications in metalworking projects.

Metal Frames and Structures: Carriage bolts can be used to assemble metal frames and structures. The square neck of the bolt fits into a square hole in the metal, preventing rotation and ensuring a secure fit.

Automotive and Machinery: In the automotive industry and machinery construction, carriage bolts are used for assembling parts that require a smooth, tamper-resistant finish. The domed head and square neck provide a secure and clean connection.

Securing Metal Panels: Carriage bolts are effective in securing metal panels to structures. The bolt’s design prevents it from turning when tightened, ensuring a stable and secure attachment.

Benefits of Using Carriage Bolts

Understanding the benefits of carriage bolts can help you decide when to use them in your projects.

Ease of Installation: The square neck of a carriage bolt allows it to grip the material, making installation easier as it prevents the bolt from turning when the nut is tightened.

Aesthetic Appeal: The rounded, domed head of carriage bolts provides a smooth and finished appearance, which is particularly desirable in visible applications such as furniture and decks.

Tamper Resistance: Once installed, the smooth head of a carriage bolt makes it difficult to remove without the proper tools, offering a level of tamper resistance.

Versatility: Carriage bolts can be used in both wood and metal applications, making them a versatile choice for various projects.

Selecting the Right Carriage Bolt

Choosing the appropriate carriage bolt involves considering factors such as material, size, and thread type.

Material: Carriage bolts are available in various materials, including stainless steel, zinc-plated steel, and galvanized steel. Choose the material based on the environmental conditions and the specific requirements of your project.

Size: Select the correct diameter and length of the carriage bolt to match the thickness of the materials being joined. The bolt should be long enough to pass through the material and allow for a nut to be securely fastened on the other side.

Thread Type: Depending on the application, you may need fully threaded or partially threaded carriage bolts. Fully threaded bolts are typically used for thinner materials, while partially threaded bolts provide additional strength for thicker materials.


Carriage bolts are a versatile and reliable fastener suitable for various woodworking and metalworking applications. Their unique design ensures ease of installation, aesthetic appeal, and secure connections. For more information on selecting the right carriage bolts for your projects, contact us. As a trusted supplier of high-quality fasteners, we are committed to providing the best solutions to meet your needs.