Wall strength question

[azgreg]

I know there has been an unlimited number of questions concerning wall construction. However, I couldn't find the answer I was looking for. Taking the two following examples, both built the same way, 3/4" frame with the voids filled with insulation, and 1/8" inner and outer skin, is either one stronger than the other? Keep in mind my build will be simple with no cabinets being attached to the walls.





The reason I ask is if there is no inherent difference that I will use the 2nd option so I can have a bit more insulation.

[dales133]

If you fully laminate the foam and frame to the internal and external ply option 2 should be fine

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[bobhenry]

I would be a little more generous with the material on the hinge side of the door and maybe the galley wall attachment area as to aid with the stress they may see during operation and travel movement.

[noseoil]

This is how I did mine. Plenty of strength, with just some "hard points" where any fastenings were used (galley, headboard, door edges, floor, roof, drink holders, windows, etc.) & we beat it up pretty well this past weekend on our trip. No problems on anything we did & it was a very rough road into the camp area.







I did add a strip of wood for the rear shelf to rest against, so the 1/8" exterior skin & aluminum don't get pushed in from any weight on the shelf bracket under a load. That's the nice thing about this way of building. Once the sides are up you can add more hard points if the need to go in.

[azgreg]

@dales133: Yes I intend to fully intend to laminate the foam and frame together with both the inner and outer skin.

@bobhenry: I intend to. Those are just two simple illustrations to show a difference.

@noseoil: Thanks for the pic.

Thanks for the replies guys.

[tony.latham]

I think cutting mortises into sandwiched walls for the bulkheads really adds strength to the structure. Those areas around the cuts need to be beefed up (widened). But if you're not going to mortise, those points still need strengthening I think.

Here's the last ten-foot long skeleton I cut. I think it's a bit chunky. But you can see where I've beefed it up to join the bulkheads.



I also agree with Tim to make sure to include hard points for anything that will be attached to the wall, such as hooks to hang your clothes aft of the door, headboards, rear shelving, countertop, etc.

Tony

p.s. And I never did use those hard points for the fenders. I prefer them attached to the chassis...

[haha49]

the outside plywood is what is going to give it's strength. The inside plywood is kind of like a spacer. I plan on building like that but instead of 1/8 plywood I plan on using carbon fiber and resin that way it's strong as steel but light weight. I would do both the inside and outside then do another to lock the roof to the walls like a big box. For the floor I would do the same thing but carbonfiber the bottom then throw a thicker sheet on top that way it's really strong I would make it so the outside walls notch into it as well that way you can screw through the bottom and the sides. The roof is the harder part since for the sides you can place it on a piece of plywood do 1 side then simply pick it up do your wiring (outside wall) then put the outside layer on when it goes back together.