Newbie Looking for Help with Wall Construction

[Kuda]

Hey all. I'm pretty new to this community and am currently in the designing phase of my first build. I wanted to get some advice in regards to how I would go about wall and insulation framing. My current build consists of a skeleton of 2x4's and 2x2's sandwiched between 1/4" interior plywood and 3/4" exterior plywood along with insulation in the voids. I am trying to keep this build under 1000 lbs (if thats even possible lol) but I still would like it to be able to have a very solid construction. Are the 2x4's overkill? Should I go with a plywood skeleton? Here's a picture of what I have made so far in regards to modeling:
Thanks for any and all input.

[tony.latham]

Are the 2x4's overkill? Should I go with a plywood skeleton?

Yes, and yes.

sandwiched between 1/4" interior plywood and 3/4" exterior plywood

And yes, that's gross overkill too. I think you'll be pushing a lot more than a thousand pounds.

This will do you fine:





Tony

[lfhoward]

Agree with Tony. ^^^^

Mine is plenty strong using 1x2’s and 1x3’s to make the 3/4” thick skeleton. Titebond II wood glue and a Kreg pocket hole jig are great for fastening the skeleton together. I used 2x2’s for the roof beams. Gluing and screwing the 1/4 ply exterior wall to the skeleton makes it a super strong monocoque structure. No 2x4’s needed.



One other way to go is to make a one piece wall skeleton from a sheet of 3/4 ply, cutting out holes for where you want the insulation to go. This may be even stronger but I couldn’t bring myself to waste that much wood, lol. But I can see how the hollowed out 3/4 ply skeleton would be easier/better to make than a stick-built frame on a traditional curvy teardrop.

[wannabefree]

I suggest you take a look in the gallery for some trailers under construction. I used 3/4 ply for the frame, but cut out as much material as I could. The way I did this was to make a 1/4 ply pattern, cut out as much waste material as I felt was safe so it looked like swiss cheese, then pattern routed out 3/4 panels for the framing. The result is I had 1-1/2w by 3/4 thick framing members with no joinery except where I spliced 2 panels together to get 10 feet length. Look at my gallery; I can't explain this better, I am afraid. I skinned the outside with 1/4 ply and inside with 1/8. The top I skinned with a double layer of 1/8 ply. My floor is 1/2 inch, next time I would go 1/4. Then I fiberglassed the whole thing.
If I ever did this again (I won't), I would not double-skin the top and would consider 1/8 for the outer walls. Ours is a very sturdy trailer. Remember a sheet of 3/4 ply is about 90 pounds. a few of those and you will have a real weight challenge on your hands. Also, give a good look at baltic birch as suggested above. It is much higher quality than anything you'll find at Home Cheapo, not much more expensive, and the strength to weight ratio it 2 to 3 times that of construction grade ply.
As has been said many times, most newbies overbuild. I get it, I did not want to build a trailer that was going to fall apart on the first trip. Trust us, good materials (baltic birch) and good joinery (screws and glue, not nails) are more important than a lot of heavy lumber.

[bartek]

I did it exactly according to Tony's picture (no surprise, I've been following his book ). My only mistake is that I didn't cut out nearly enough from the plywood skeleton, so I'm sure the result is way heavier than it needed to be... Only after building have I realized how much of the strength comes from the torsion box design.
I also decided to double skin the top - will know how much of a mistake that was once I'm ready to drive to the scale

[DaddyJeep]

My skeleton structure is 1/2" plywood cut into 1" strips and doubled to make 1x1's. Now that I am getting 1/4" ply on the outside it is already getting nice and strong. Once I clue in the foam and get the inner skin on there will be no worries.

[bobhenry]

This was the last studded skeleton I built with 2 x 3's 1 1/2 by 2 1/2 actual with 1" x 1" wind bracing let in diagonally.

After this the next 2 builds were designed as ultra lights. Rip van winkle was a 4 x 7 build to tow with the Goldwing. It came in at #525 pounds ready to camp. It was a plywood sided build



spars were rabbeted and set in pockets the screws were angled up across grain rather than just straight into the end.

Yes you now have a wiggly box !

Half walls were added to offer stability and reinforcement. By cutting in access holes I was able to create storage shelves

These front and rear wall inserts took all the wiggle out of the box

The storage shelving was a very welcome addition

Lest you think we left out the creature comforts like insulation I wrapped 1 1/2 blue foam cut to fit with a heavy weight material for good looks and stuffed them into place.

the torsion box floor was filled with closed cell insulation and an OSB panel was placed on top for the sub flooring.

And yes it has a 10 foot wide kitchen. ( just wide enough to tuck under a 10 x 10 popup)

[noseoil]

Similar to Tony's, but I used 3/4" frame with 1/8" skins both inside & outside. Plenty strong & light, 3/4" insulation in the sides.