Minimum wall thickness?

[WillemII]

Hi all,

I am still in the planning stage for my TD. The one thing that I have to keep in mind all the time is WEIGHT. My tow car legally allows only 400 kg (880 lbs) to be towed, that is a braked trailer.
Still working on a profile, but the width will be 4' (length probably around 8-9').
Starting from a lightweight New Cub style trailer frame, I intend to use 1/2" ply for the bottom and sides. Bottom to be insulated with 1" foam below, walls will have 3/8" EPP foam on the inside with a finish of vinyl upholstery material. (we call it skai, imitation leather). Roof will be standard, 1/8" inside and outside, insulating foam in between.
Any thoughts, or better even, any comments on going this 'light' way?

Willem

[absolutsnwbrdr]

Sounds like you have a pretty good plan already. Structurally speaking, your wall thickness sounds fine. Have you thought about doors and windows? If you purchase premade doors and windows, they will sometimes suggest a minimum wall thickness. And sometimes you can get different trim rings for different wall thicknesses.

Also, there are many people (myself included) that see no advantage to having underfloor insulation. Heat rises, so the roof insulation is really what matters most. Also, if you are planning on having a foam mattress, this will function as floor insulation.

[angib]

1/2" for the sides and bottom isn't very light. You can go down to 3/8" (10mm) for the floor if you have enough framing. On the sides, I think 1/4" (6mm) will be strong enough with plenty of framing. The framing needs to be kept light too, so for a lightweight build I would go down to 1x1 (20x20mm finished) framing with 1x2 (40x20) at places like door frames. 20mm framing means you can use 19mm insulation foam in between.

[WillemII]

@ Zach:
I think you are right about the underfloor insulation. In any case, we are not cold weather campers.
I had considered premade doors, but most manufacturers over here state a minimum wall thickness of 28 mm (1 1/8").
So I'll go the home made way. In fact I plan on making the doors approx. 1 1/2" larger than the door opening, so that the door actually sits on the outside against the 'body'. Less hassle with alu trimming (none) and sealing should be easy. Still looking at suitable hinges, possibly live hinges.

@ angib:
Thanks for your comment. I was hoping to stay away from framing in the walls, for that reason I thought of 12 mm ply. A sheet of 4' by 8 1/2' weighs 18 kg, so that would give me around 50 kg for floor and walls. I predict another 18 kg for the insulated roof ( 2 layers of 3 mm ply plus spars) and hatch, which will be single skin 3mm.

Willem