Teardrops n Tiny Travel Trailers

tony.latham wrote:

QQ; the benefits vs a full sheet are mainly for weight and if weight is not a concern it's fine to go with a full 3/4 sheet?

If you are asking about the benefit of a sandwiched wall vs a solid one, here's my opinion:

1. The resulting structure is a torsion box that is stiffer than a single sheet of plywood with close to the same weight.

2. This method makes it easy to "stretch" plywood beyond the normal 8' length using a simple spline joint in the skeleton cut with a router bit. The exterior/interior sheathing that is glued on acts as a gusset and strengthens the joint.

3. Insulation. I purchased my first teardrop in 2004. It had solid plywood walls. On cold mornings we would always get condensation on the walls. We kept a bath towel in the cabin just to wipe them down in the morning. This would happen even with the cabin well ventilated. Condensation doesn't form on insulated walls.

4. A thicker wall allows for deep dados (or slots) to be included in the wall for bulkheads and any other cross members. This joinery makes for a much stronger cabin and is easier to assemble since these parts just slip inside the walls. Think mortise and tenon. (And yes, this is easy to do with a simple router jig.)

5. The thicker wall allows for a lip to be formed on top of the wall so that the headliner can be installed prior to the spars. This creates a perfect interior wall/ceiling joint that doesn't need to be covered by trim. (Having done this a few times, I can't even imagine having to install the headliner after the spars are installed.)

6. The thicker wall allows for a Fredricks style hatch that has a seal system that is water and dustproof.

Sandwiched walls are more labor-intensive but you end up with a stronger cabin that is insulated with a galley that doesn't leak.

Tony