Need help deciding on wall construction method.

[theoldwizard1]

I have been contemplating building a trailer, but a full sized one. Here are a couple of things to think about.

Whatever your choice of exterior "skin" (sheathing), its primary purpose to to prevent the wall from "racking". Side walls need to resist front to back racking. Front and rear walls, side to side racking. This is why on full size trailers they use Azdel (a non-organic stiff panel that replaces luan or plywood) attached to the "studs" underneath Filon (a flexible, continuous "rolled" non-organic finish covering.

Construction grade lumber (2x2 or 2x4) is the obvious choice for studs and roof rafter for DIY builders. Aluminum is much lighter, but more expensive and requires welding.

Solid foam between the studs help prevent racking and should allow you to down size the studs.

The traditional material for floors is 3/4" plywood. You could use 1/2" plywood if you placed a couple of layers of epoxy and fiberglass on all sides. At a minimum. paint all sides with a good oil based primer and paint. If you have the money and time, foam with multiple layers of epoxy and figerglaa or 3/4"honeycomb panels.

As previously pointed out, the connection of wall to floor and wall to ceiling is CRITICAL. It prevents side to side racking. Extremely stiff front and rear wall, properly attached help, but the longer the box (trailer) the less effective they become. The best solution is the ugliest; GUSSETS ! On a large trailer you can hide them by building them into cabinetry. Side to side flexing will cause the joint between wall and celing or wall and floor to fail or at least leak over time,