Teardrops n Tiny Travel Trailers

My build will be a skeleton of Okoumé plywood of 18mm (3/4"). On the inside the skeleton will be covered with a 4mm (1/8") lightweight multiplex. The wall will then be isolated with EPS foam that I have cut to exact thickness. Our TearDrop will be skinned with what is called Alupanel, a lightweight sandwich plate of aluminium, foam and aluminium. Total thickness will be 3mm (3/32"). This is a material that I can get in large enough sheets to cover the walls with one plate. And since our Teardrop is quite long (12ft) and high (almost 5ft) this will be an easy solution.

I am wondering if it is necessary to install wooden plating on the outside of the wall as well or that I can mount directly on the skeletonized plywood walls.

I don't see why you couldn't but any leak at all will go straight to the interior of your wall. That would be bad. Hopefully one of the pros here will respond but I certainly think you could as long as your skeleton provides enough material to fasten it well.

I am wondering if it is necessary to install wooden plating on the outside of the wall as well or that I can mount directly on the skeletonized plywood walls.

If you are bonding the stuff to the skeleton, then no. (And I mean bonding as in permanently glued. If not, I think you need exterior plywood sheathing for strength and sealing. The unskinned skeleton isn't very strong.

Tony

You might consider aluminum studs/skeleton then apply your exterior panels.