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Coach bolts are widely used across fencing, gate installation and timber frame construction. Their square neck and domed head provide a secure fixing with a clean finish on exposed surfaces.
This guide covers how coach bolts are used in practice, which sizes are typically selected, and how to choose the right material for the job.
Coach bolts are designed for through-fixing. The square section under the head locks into the timber, preventing rotation while tightening the nut.
In fencing applications, coach bolts are commonly used to fix rails to posts and secure timber components.
M8 and M10 coach bolts are typically used for standard fencing work, depending on timber size and load.
Gates place higher loads on fixings due to movement and weight. Coach bolts are commonly used to secure hinges, braces and frame connections.
M10 and M12 coach bolts are commonly used for gate installations where additional strength is required.
In timber frame construction, coach bolts are used for structural connections between larger timber sections.
M12 and above are typically used depending on load and design requirements.
| Application | Typical Size |
|---|---|
| Fencing | M8 – M10 |
| Gates | M10 – M12 |
| Timber frames | M12 and above |
The bolt should pass through all materials and allow enough thread for a washer and nut.
Material choice is important for fencing and external timber work.
For more detail, see our A2 vs A4 stainless steel guide.
Coach bolts are used where a through-fixing is possible and maximum strength is required.
Coach screws are often used where access is only available from one side.
See our coach bolts vs coach screws guide for a full comparison.
M8 or M10 are commonly used depending on timber size and application.
M10 or M12 are typically used for gate installations where higher strength is required.
Yes. Coach bolts are commonly used in timber frame construction for secure structural connections.
Yes. Stainless steel is recommended for external use, with A4 preferred in harsher environments.
Contact TC Fixings for advice on sizes, materials and product availability.
Posted: 23rd March 2026
Author: TC Fixings
