Lag Bolts vs Carriage Bolts: Choosing the Best Option for Your Project

When it comes to fastening heavy-duty materials, especially in construction and building projects, bolts are a staple. But not all bolts are built the same. Two of the most commonly used types are lag bolts and carriage bolts. Each has specific strengths and ideal use cases, and understanding the differences can make the difference between a solid, long-lasting connection and a costly do-over.

This guide breaks down what you need to know about lag bolts and carriage bolts so you can choose the right fastener for your next job.

What Are Lag Bolts?

Lag screws, commonly referred to as lag bolts, are robust fasteners primarily employed to secure wood to other wood surfaces or to masonry structures. Unlike machine bolts, lag bolts have a pointed tip and coarse threading, allowing them to be driven directly into wood without the need for a nut.

Key Features:

• Coarse threads for gripping wood securely
• Hex head for use with a wrench or socket
• Commonly used in structural woodwork and outdoor construction

Common Uses:

• Securing beams and posts
• Mounting heavy items to walls

Deck building

Lag bolts are ideal when you need high shear strength and holding power. They bite deep into the wood, creating a robust and durable connection.

What Are Carriage Bolts?

Carriage bolts are a type of machine bolt featuring a dome-shaped head and a square shoulder positioned directly under the head. This design prevents the bolt from spinning once its inserted into a square hole or pulled into wood.

Key Features:

• Smooth domed head for a clean finish
• Square neck to prevent rotation during tightening
• Requires a nut and washer on the opposite side

Common Uses:

• Wood-to-wood connections where the bolt head will be visible
• Fence building and outdoor furniture
• Projects requiring tamper resistance

Due to their sleek look and anti-tamper features, carriage bolts are frequently chosen in applications where visual appeal and protection against tampering are important.

Head-to-Head Comparison

1. Feature
2. Lag Bolts
3. Carriage Bolts
4. Installation
5. Direct into wood
6. Requires access to both sides
7. Tools Required
8. Wrench or socket
9. Wrench + hammer for square neck
10. Holding Power
11. Excellent for wood
12. Strong but relies on nut torque
13. Vibration Resistance
14. High
15. Moderate
16. Aesthetic Finish
17. Industrial look
18. Clean, rounded appearance
19. Tamper Resistance
20. Low
21. Moderate to high

Choosing the Right Bolt for Your Project

Use Lag Bolts When:

• You need to fasten wood to a structure without access to the back side.
• Strength and structural integrity are critical.
• Speed and ease of installation are important.

Use Carriage Bolts When:

• You can access both sides of the material.
• Appearance matters (e.g., exposed bolt heads).
• You need added security and tamper resistance.

Material and Coating Options

Lag bolts and carriage bolts are available in various materials such as:

1. Zinc-plated steel for indoor use
2. Hot-dip galvanized steel for corrosion resistance outdoors
3. Stainless steel for marine and high-moisture environments

Selecting the right finish ensures your fasteners last as long as the materials they hold together.

Final Thoughts

In the battle of lag bolts vs carriage bolts, the best choice depends on your specific project requirements. If you're working with structural wood and need strength with one-sided access, lag bolts are your go-to. If you're constructing something where appearance and tamper-resistance matter, carriage bolts offer both form and function.

At baut - tokohasil, we stock a wide range of high-quality bolts for every type of construction job. Whether you're building a deck, framing a structure, or assembling outdoor furniture, we have the fasteners you need to get the job done right.

Explore our full selection of bolts today and make sure your next project is built to last.