Enclosed Trailer Wall Construction

This is the first article of a ten-part series discussing the various individual components of enclosed trailers and how they will relate to the long-term stability of your trailer.

One of the most important components of enclosed trailers is their wall construction. Wall constructions come in a variety of combinations. Most enclosed trailers will use aluminum, steel, galvanized steel sometimes referred to as Galvaneal; or FRP. For wall cross members, steel or aluminum is used. Attached to the cross members is plywood, luan, aluminum or a combination of these.


Most commonly used is the aluminum exterior. Normally ranging in thickness from .024 – .050, aluminum is the most common form of exterior. It is durable, lasts long, and does not rust. It is the lightest materials used for the exterior of an enclosed trailer. These are applied in panels using screws, rivets, 3M adhesive tape or an industrial epoxy. Using thicker exterior aluminum will generally increase trailer stability and preserve the aesthetics of the trailer longer. FRP (Fiberglass Reinforced Plastics) is a fiberglass based wall than lasts long and is easy to repair. FRP is normally only available in white. Steel and galvanized steel are generally the least desirable exterior as they will rust and tend to deteriorate rapidly.

Cross Members

The materials used to build the wall cross members are made of steel or aluminum. The steel variety is implemented using either a z-channel, hat post or box tube. Hat post implementations use the same steel configuration as road signs, while z-channel is a hat post cut in half. A box tube has steel on all four sides and is generally considered the most desirable due to strength. Z-channel is the least desirable because of their strength while hat post is cost compromise between box tube and z-channel. For commercial uses or if your application requires wall mounted devices, box tube is a must. Generally, enclosed trailers with hot post a z-channel tend to have their exteriors look “wavy” over time. Normally, cross members are 16″ on center. Some manufacturers use 24″ on center, consumers should be wary of these trailers if they also use z-channel or hat post because of the lack of strength.

Wall Material

Generally, with hat post and z-channel, the walls will have plywood reinforcement. Plywood will add weight over luan with box tube. Looking long term, it is more economical to pay more for a box tub wall trailer if the trailer is used frequently due to added fuel costs. Interior aluminum walls are aesthetically pleasing and are easily cleaned. Some trailers offer a white vinyl coating over luan called designer board. These walls are also easy to clean with a lesser cost than aluminum.