Building wooden sides onto a car trailer allows for hauling more than just cars. Adding the wooden sides will prevent smaller items like mulch or dirt from falling off the sides of the trailer. Building the wood sides is a task that can be completed in one day, and the entire project does not require any special tools or knowledge. The wood used for this project does not need to be pressure treated lumber if paint or stain is used.
Measure the length of the car trailer.
Divide the length of the trailer by 2 to determine the amount of support boards needed. For example if the trailer is 10 feet long, you will need five support boards. Round the number if you get an odd amount. This number is also the amount of side posts needed for each side. Double that amount to accommodate both sides. Cut the appropriate amount of 2-by-4 boards to 24 inches long.
Cut four 2-by-4 boards to match the length of the car trailer. These boards will be known as the top and bottom length.
Lay the 24-inch long 2-by-4 boards on a flat surface. Space them two feet apart. Attach the top length board to the top of each 24 inch side post using two 2-inch screws. Repeat with the bottom length board.
Repeat steps 1-4 with the width of the trailer. Only create one side for the width. The front of the trailer will be left open.
Attach the railing to the trailer by standing the frame up on the edge of the trailer. Drill two holes through the bottom of the frame into the trailer between each side post. Ensure that the drill bit goes completely through the trailer and can be seen from the bottom.
Slide a bolt through the hole and connect a nut to the other end. Tighten the bolt to ensure that the rail is held in place securely. Repeat with the two other sides.
Measure and cut 3/4-inch plywood to cover the outside of the frame. Attach the plywood to the rail using two inch screws.
Build a hinged door for the front of the trailer if desired by cutting a piece of 3/4-inch plywood to fit the opening. Attach it to the trailer using one large hinge at the base. Attach a latch at the top of the wooden frame to hold the door closed.
Paint, stain or seal the wood on the car trailer by following specific manufacturer instructions.