Utility trailers are just that -- trailers used for a variety of purposes, from hauling limbs and debris to carrying lawn tractors and all-terrain vehicles. Utility trailers are only as good as their sides. A trailer with a flat bed can carry vehicles and lumber or other flat material, but to be really useful a trailer needs sides. These can be mounted permanently or made for easy removal. They usually are made of wood. Use of the trailer and individual preference will detemine the type of trailer sides.
Measure the length of the utility trailer and decide how high to make the sides. Most will be at least 24 inches, some as high as 36 or 48 inches. The material to be hauled in the trailer will influence this decision. Hauling light material such as lawn and tree debris will use higher sides. Heavier material such as sand, gravel or dirt, can have lower sides.
Locate the stake holes. These will either be 2-by-4-inch brackets welded to the sides of the trailer or slots if the trailer has metal sides part way up. Trailers will have 2 to 8 brackets, depending on the length of the trailer. Most 8-foot utility trailers will have 2 on each side and 2 each front and back.
Cut 2-by-4-inch boards to fit in the brackets, extending at least a foot below the trailer bed and to the determined height of the sides. For 24-inch sides, make 2-by-4s 36 inches long. Cut 1-by-12-inch siding boards to the length of the trailer or cut plywood panels to the height and length for the trailer sides.
Attach the side panels to the 2-by-4 uprights with galvanized screws. Use a carpenter's square to make sure uprights and panels are square. Make similar panels for the front and back, if desired. Slide the 2-by-4s into the brackets; secure with screws in holes drilled through the brackets for permanent sides or leave loose to easily remove sides.