Materials: Steel vs Aluminium
Enclosed trailers have two separate material decisions to make — the chassis, and the wall/roof panels — where a box trailer only really has one.
Chassis Material
Hot-dip galvanised steel remains the standard chassis choice for the same reasons as any other trailer type — full corrosion protection including welds and internal members, greater strength per unit thickness than aluminium. This matters more, not less, on an enclosed trailer, since the chassis is carrying the additional tare weight of the walls and roof on top of cargo.
Wall & Roof Panels
Aluminium composite or sheet aluminium panels are common for the enclosed skin specifically — lighter than steel panels, which meaningfully offsets the tare-weight penalty of being fully enclosed in the first place, while still being naturally corrosion-resistant without needing galvanising. Steel panels are stronger against impact and cheaper, at the cost of extra weight exactly where an enclosed trailer can least afford it.
Floor
Plywood-over-steel-frame flooring is common and cost-effective; checker plate metal flooring is more durable and easier to clean, particularly relevant if the trailer doubles as a mobile workshop where tools, fuel or chemicals might be spilled.
Questions & Answers
Should the chassis and panels be the same material?
Not necessarily — a galvanised steel chassis for strength and corrosion resistance paired with lighter aluminium wall/roof panels is a common and sensible combination, offsetting some of the tare-weight penalty of being fully enclosed.
Is plywood or checker plate flooring better for an enclosed trailer?
Checker plate is more durable and easier to clean — worth it for a mobile workshop or trailer regularly exposed to fuel/chemical spills. Plywood is cheaper and adequate for lighter, drier cargo.