side walls..solid or sandwich?

[charlescranfill]

newbie question alert!

OK, so my choices for the side walls, as I understand it:

3/4" solid plywood, single thickness walls
or
sandwich construction - which I think I prefer to keep the weight down, as well as allowing me a place to route wiring. So would 1/8" plywood glued over 1x2 framing be strong enough? I have plenty of internal bracing planned, what with the bunkbeds and cabinets..I think...? If it matters, I'm hoping to do a 6Wx6Hx10L standy.

[H.A.]

.

[GuitarPhotog]

Are you going to be needing insulation in those side walls? Solid plywood walls have little insulation value.

<Chas>

[charlescranfill]

Sorry, I wasn't real clear on the actual question...I think I've decided that I like the sandwich over the solid.

For the sandwich construction, is 1/8" plywood sufficient, or do I need 1/4"?

[Shadow Catcher]

Our walls are stress panel with 1/8' Filon Luan laminate outer 1/8 inner between 1.5" aluminum frame and foam. The roof is the same construction and strong enough to walk on.

[charlescranfill]

sweet! when you say it's 'stress panel"..what does that mean, exactly?

[KCStudly]

The frames, foam, and plys are all glued up in a big sandwich with no voids or unglued areas. Unit construction. No slip planes (provided the bonds hold). Makes the most of the available strength of the individual materials by using the core to stabilize the inner and outer skins.

If you just nail the panels to the frame without full face gluing, the panels can buckle away from the foam and will fail before the same schedule of materials would if they are fully bonded.

Short answer: fit everything fair, flush and flat; and glue everything together flat (lots of evenly distributed weight to clamp).

Google SIP (structural insulated panel).

[KCStudly]

Well, er, more directly to your question; a stress panel is a panel where the skin of the panel is the primary structural member, and the frame or core is there as a supporting roll (similar to a shear panel in your house); as opposed to something like a non-load bearing wall in your home, where the wall studs are merely there to hold the dry wall up; or a load bearing wall in your house where the studs do the 'heavy lifting' and the dry wall does not much.

With a stress panel the skins are acting more like the top and bottom flanges of an I-beam. The outer fibers do the work and the inner fibers just keep the outer fibers 'out'. By using lighter weight material to keep the outer fibers stable in their outward position, the wall (or floor, or roof) will be just as structurally sound, but can be lighter, so long as it has sufficient localized puncture resistance.

Have you seen the foamie section? Lots of variations on the concept: foam board with painted canvas inner and outer walls; foam board with minimal wood framing, painted canvas outer and painted chip board (paper card) inner; thin wood inner, unitized cabinetry, foam board and painted canvas outer; ply wood inner cabinet structure, foam board with epoxy/glass outer; and more.

[charlescranfill]

all of that makes perfect sense. thanks a ton folks.

[citylights]

all of that makes perfect sense. thanks a ton folks.

I went with 3/4 plywood side walls. Solid, simple, quick, and freeking heavy! Check my build page for pictures.

If I was to do it again, I would go with 1/8 th inch plywood inside wall, 1 inch foam core, 1/8th inch outside plywood, all sandwich glued, then 0.04 thk aluminum outside.

[charlescranfill]

thanks a ton folks. After looking around here, I think I have decided to use a single sheet of 3/4" plywood - but I'mma cut holes in it so it mimicks a frame built of 1x2. That gives me a lot of my cabinet panels as well as a modular frame with no screws or gluing involved. I'll glue foam panels into the 'panes', then sandwich it with 1/8" luan. I think this should work out real nice, we'll see.

[KCStudly]

We (I) call that the skeleton wall frame technique.

DMcCam's Atma Travelear is a great example.

[charlescranfill]

so would this be OK, yall think? interior 1/8" luan, skeleton wall frame of exterior grade 3/4" plywood, exterior skin of FRP glued directly to the 3/4"? Skip the exterior layer of 1/8"? Or will the FRP crack and break in that scenario? I'm concerned about the voids(albeit with foam panels in them) under the FRP.

[mikeschn]

I'd like to hear from Grant, many of the original teardrops were build with solid walls. And Grant even has door hinges for those solid walls. But the questions I have is, what was the thickness of those walls... 2nd and 3rd picture at this link: http://www.lilbear.teardrops.net/parts.html#hinge

Mike...

[charlescranfill]

I keep waffling. I could go for 3/4" solid with the pretty side inward, glue FRP on the outside. Easy to build..I was hoping to save weight with the sandwich. Decisions, decisions. LOL