Help with walls

[Tripmaker]

I built my first TD in 2006 following the Generic Benroy plans. 3/4 ply on a Red Trailer extended to 5 x 10. Skinned in AL, and loaded to camp, it weighs in at 1,410 lbs. Other than the single bar tongue breaking in Arizona 80 miles from the nearest welding shop, I have had no problems. Built like a tank, acceptable weight, and pulls nicely behind my Honda Ridgeline.

I'm now looking at trailer number two. I have a 75" x 142" pop up frame on which I plan to build using a Cabin Car or Campster 12 profile. Either one will be skinned in AL, I enjoy building but I hate maintenance. As it will be a larger camper I am looking to save weigh where I can and still stay under 2,000 lbs. I am considering two options for the walls.

1. Build the walls with 1/2 ply. Is 1/2 ply is strong enough for a camper this size?

2. Frame the walls out of 1x2's, insulate and skin in 1/4 ply. This would not save weight over option 1 but should be warmer. Would I need the exterior 1/4 if I am skinning in AL? I know the commercial campers have nothing but the AL skin and that again would save weight.

Or is there an option 3? I looked at the way Grant makes his walls for the Campster 12, cutting out sections of 3/4 ply and filling with insulation, but this looks to be quite labor intensive.

What are your thoughts and suggestions?

As always, thanks in advance for your help.

Jim

[noseoil]

I'm using a "skeletonized" 3/4" plywood panel (see my build thread if you want to look at the method) with 1/8" Baltic Burch skins inside & out. That having been said, I've never built one of these things, so you have more experience than I do at this point. Take everything I say with a large pinch of salt.

Plus side on this type is:

Light & relatively strong the way I'm doing it. The actual wall is about an inch thick and there's foam sandwiched between the 1/8" panels as filler pieces inset in the 3/4" plywood. It has good insulation for a thin side panel. It's a lot easier than joining all of those pieces of 3/4" solid wood with screws & glue to make curves and straight lines, so it's faster. I made one side then used a router and a flush-cut bit to transfer the design to the opposite side Presto! Identical panels are done. The 4' x 9' wall frames weigh in at 17# each without the skins, pretty light so far.

Minus side:

There's a lot of waste involved in this process. You're throwing away 80% of the 3/4" plywood (at about $40 per sheet) this way. You really have to think to make sure your design is correct, or any "hard points" for connections will be missing if you need to attach things later on in the build.

For me it was the best choice in weight, cost, strength, ease of build & faster work. Every build is different, but 1/8" skins which are glued in place will be plenty strong enough for your build, if the frame is glued to it. 3/4" solid wood, 1/2" plywood, whatever, will work.

[Tripmaker]

Just looked at your build thread. Nice work and I see how you saved a bunch of weight. Like you I am starting with a heavy trailer. Also like you I am in no rush to get it done. I have work to do on my trailer frame before I start cutting wood as I am planning on a drop floor. I am also considering replacing my leaf spring axle with a torsion axle in order to lower the trailer.

I agree with your thoughts on getting major components, doors, windows, etc. before building so that I know what I need to cut and where. Not sure what I'll do with the walls yet but I have time. For ease of building I'm thinking 1/2" ply. Menard's carries a pre finished sealed birch ply that would save on a bunch of labor not having to sand and seal the inside walls.

I'll start a build thread when I have something to show.

Thanks

[rowerwet]

just build the walls out of foam, next to no waste, and super lightweight

[Tripmaker]

I've been reading about the foamies. From what I understand about them, which admittedly isn't much, they get much of their strength from the canvas. Not so sure how it would work out skinned in AL. I do want a wood interior though and that would give it some strength. Then I wonder about attaching shelves etc. with screws. At 65 I can be hard headed about somethings, but I'm trying to keep an open mind.

[Greg Barrick]

just my .02 cents. I built my campster 12 using 3/8" ply outside, 1x2 (ripped 2x4) wall studs and 1/8 ply interior. No insulation. No problems in 2 years. My previous teardrop was 0nly 4x8 with insulation. Extremely warm in the summer months. I probably should have added insulation to my campster 12, just for more rigidigitty, but was being "frugal" at the time. Have used it down into the 30's, cool but comfortable in the mornings.

[Tripmaker]

I just like the looks of aluminum and no exterior maintenance issues. As far as insulation goes I see it as something to fill the walls with if I stick frame it. My TD with 3/4 ply and insulation only in the roof is plenty warm.

Decisions, decisions.

[tony.latham]

I just like the looks of aluminum and no exterior maintenance issues. As far as insulation goes I see it as something to fill the walls with if I stick frame it. My TD with 3/4 ply and insulation only in the roof is plenty warm.

Decisions, decisions.

My old Hunter teardrop had solid plywood walls and we got a considerable amount of condensation, even with the windows cracked. With our 5-wide constructed with sandwiched walls (insulated with 3/4" of foam) we get no condensation on the walls. Warmer? Hard to compare jumping from a 4-wide to a 5-wide, but it is dead quiet with the insulated walls.

T

[Tripmaker]

Good point. We get condensation as well unless the windows are open a few inches.

[rowerwet]

I've been reading about the foamies. From what I understand about them, which admittedly isn't much, they get much of their strength from the canvas. Not so sure how it would work out skinned in AL. I do want a wood interior though and that would give it some strength. Then I wonder about attaching shelves etc. with screws. At 65 I can be hard headed about somethings, but I'm trying to keep an open mind.

If you check most foami builds, there are two major ways to attach shelves door hinges etc. Cut a groove in the foam, glue wood into the groove, now you have a cleat to attach things to. The other way is to put in thin vertical framing supporting the shelves. Either way glued joints are much better for strength.
For AL skin on a foamie, float it on the same way most AL skin is, with window, door, and edge trim actually holding it on.

[tony.latham]

I've been reading about the foamies. From what I understand about them, which admittedly isn't much, they get much of their strength from the canvas. Not so sure how it would work out skinned in AL. I do want a wood interior though and that would give it some strength. Then I wonder about attaching shelves etc. with screws. At 65 I can be hard headed about somethings, but I'm trying to keep an open mind.

If you check most foami builds, there are two major ways to attach shelves door hinges etc. Cut a groove in the foam, glue wood into the groove, now you have a cleat to attach things to. The other way is to put in thin vertical framing supporting the shelves. Either way glued joints are much better for strength.
For AL skin on a foamie, float it on the same way most AL skin is, with window, door, and edge trim actually holding it on.

Rowerwet: Out of curiosity, when you skin a foamie with aluminum, how do you attach the trim? Obviously with a traditional built 'drop, you screws the trim down with screws.


Thanks,

T

[rowerwet]

Run a wood "frame" along the edge of the foam, 1" square glued into a rabbet in the foam would allow you to screw on the trim. Just make sure the wood sits flush.
Steaming the wood would allow almost any radius bend.