How to Build Sides on a Flatbed Trailer: A Comprehensive Guide

Building sides on a flatbed trailer dramatically increases its versatility, allowing you to haul loose materials, equipment, and cargo more securely. This guide provides a step-by-step process for constructing robust and reliable sides, enhancing your trailer’s functionality and ensuring safe transport.

Understanding the Basics

Building sides for a flatbed trailer is a project best approached with careful planning and a commitment to safety. The goal is to create a secure enclosure that can withstand the stresses of hauling different types of loads while remaining relatively easy to install and remove. The key considerations are material selection, structural integrity, and secure attachment to the trailer frame.

Material Selection: Choosing the Right Wood and Metal

Choosing the right materials is paramount for durability and longevity. Common materials include treated lumber, steel tubing, and metal sheeting.

Treated Lumber

Pros: Relatively inexpensive, easy to work with, and readily available.
Cons: Prone to rot and decay over time, susceptible to damage from impacts, and heavier than some alternatives.
Best Uses: For light-duty hauling and temporary side construction. Consider using pressure-treated lumber that is specifically designed for ground contact.

Steel Tubing

Pros: Strong, durable, and relatively lightweight. Can be welded for a seamless connection.
Cons: Requires welding skills and equipment. Can rust if not properly protected with paint or powder coating.
Best Uses: For framing the sides and creating a strong, rigid structure. Square or rectangular tubing is generally preferred for its strength and ease of joining.

Metal Sheeting (Steel or Aluminum)

Pros: Offers a smooth, protective surface. Steel is stronger, while aluminum is lighter and more corrosion-resistant.
Cons: Can be dented or damaged by impacts. Steel is heavier and prone to rust. Aluminum is more expensive.
Best Uses: For creating the actual walls of the sides. Consider the thickness of the sheeting based on the type of materials you’ll be hauling.

Planning and Design: Laying the Groundwork

Before you start cutting and assembling, a well-thought-out plan is essential.

Measuring Your Trailer

Accurately measure the length and width of your trailer bed. This will determine the overall dimensions of your sides.
Note the location of any existing stake pockets or other attachment points on the trailer frame.

Determining Side Height

Decide how high you want your sides to be. This will depend on the types of materials you plan to haul.
Consider local regulations regarding side height requirements for different types of cargo.

Creating a Sketch

Sketch out a detailed plan of your sides, including the dimensions of each piece of lumber or steel.
Indicate the location of all attachment points and any bracing or supports that will be needed.

Construction: Building the Sides

This section outlines the steps involved in constructing your trailer sides.

Framing the Sides

Cut the steel tubing (or lumber) to the dimensions specified in your plan.
Weld (or bolt) the tubing together to create a rectangular frame for each side. Ensure all corners are square.
Add vertical supports to the frame for added strength and stability.

Attaching the Sheeting

Cut the metal sheeting to the appropriate size.
Attach the sheeting to the frame using screws, rivets, or welds.
Overlap the edges of the sheeting slightly to prevent leaks.

Creating Attachment Points

Design attachment points that will securely connect the sides to the trailer frame.
Consider using stake pockets, bolts, or clamps.
Ensure the attachment points are strong enough to withstand the forces of hauling.

Finishing Touches: Adding Protection and Refinement

Protecting your investment and enhancing the functionality of the sides are important final steps.

Painting or Coating

Apply a coat of paint or powder coating to the steel frame and sheeting to prevent rust and corrosion.
Use a primer to ensure proper adhesion of the paint or coating.

Adding Reflectors

Install reflectors on the sides to improve visibility, especially at night.

Weatherproofing

Seal any gaps or cracks in the sides to prevent water from entering.
Consider using a weather-resistant sealant or caulk.

Frequently Asked Questions (FAQs)

Here are some common questions regarding building sides on a flatbed trailer:

What is the best type of wood for building trailer sides? Pressure-treated lumber designed for ground contact is the best choice for wooden trailer sides due to its resistance to rot and insect infestation. However, be aware that treated lumber is still heavier than steel or aluminum.
Can I build trailer sides using only wood, or is metal necessary? You can build sides using only wood, especially for lighter loads. However, metal provides superior strength and durability, making it a better choice for heavier or more demanding applications.
What gauge of steel tubing should I use for the frame? A 14-gauge or 16-gauge steel tubing is generally sufficient for the frame, providing a good balance of strength and weight. For heavier loads or longer trailers, consider using a thicker gauge.
How should I attach the sides to the trailer frame? Stake pockets, bolting, or clamping are common methods. Stake pockets offer easy removal, while bolting provides a more permanent and secure connection. Clamps are useful for temporary installations. Ensure the attachment method is strong enough to handle the load.
What kind of screws are best for attaching metal sheeting to a wooden frame? Use self-tapping screws specifically designed for metal-to-wood applications. These screws have a drill point that allows them to easily penetrate the metal and securely fasten it to the wood.
Is welding required for building trailer sides? Welding is not strictly required, but it significantly enhances the strength and rigidity of the sides, especially if using steel tubing. If you’re not comfortable welding, consider using bolted connections.
How can I prevent rust on my steel trailer sides? Proper preparation and painting or powder coating are crucial. Start by cleaning the steel thoroughly and applying a rust-inhibiting primer. Follow with several coats of durable paint or a powder coating for maximum protection.
What is the maximum height allowed for trailer sides? Regulations vary by state and by the type of cargo being hauled. Check with your local Department of Transportation (DOT) or equivalent agency to determine the maximum allowable height for trailer sides in your area.
Can I use aluminum for trailer sides? Yes, aluminum is a good alternative to steel due to its lighter weight and corrosion resistance. However, aluminum is more expensive than steel and may not be as strong.
How do I ensure the sides are square and plumb? Use a square and a level throughout the construction process. Check the angles of the frame and ensure the sides are plumb (vertical) before permanently attaching them to the trailer.
What type of bracing or supports should I use? Diagonal bracing significantly strengthens the sides and prevents them from flexing or collapsing under load. Consider adding vertical supports as well, especially for taller sides.
How do I safely load and unload materials from a trailer with sides? Always distribute the load evenly across the trailer bed. Use ramps or forklifts to safely load and unload heavy items. Secure the load with straps, chains, or nets to prevent it from shifting during transport.

Conclusion

Building sides on a flatbed trailer is a rewarding project that significantly increases its utility. By carefully planning, choosing the right materials, and following the steps outlined in this guide, you can construct robust and reliable sides that will serve you well for years to come. Remember to prioritize safety and consult with experienced professionals if you have any questions or concerns. With a little effort and attention to detail, you can transform your flatbed trailer into a versatile hauling machine.