Dumb framing/ 'sandwich wall' construction question....

[Billy K]

Hopefully I'll not hi-jack this thread , but add to the question .....

If, I build with the plywood core theory; How would I wire the walls for a light or speaker?

If, I want a light outside as a porch light....?

I get the part about wasted time and effort. I'm wondering more about usability of the sandwich space.

Does the plywood have as much R value as the insulation?

[bobhenry]

In most tears the bulk of the wiring is in the galley wall and the cabinets
(Front and Rear) what little wireing in the side walls is usually routed thru the roof spars by drilling a small hole for stranded wire. The plywood can be routed with a trough for the wiring from roof to sidewall but be very mindful of where these wires are located and avoid nailing thru them when lining the inside.

[alffink]

Billy

As BobHenry, stated most of your wiring will route from the Bulkhead seperating cabin from the galley, now that is not any kind of a rule, a few have used a tounge box to be thier electrical cabinet then ran, every thing from there, either through the cieling or underneath the trailer, it's your build.

But, your question was how to route thru the sandwich wall, well in my case, I used the ceiling to route the wires for my speakers, reading lights, dome light, and wiring for a powered vent/fan. I also ran the wires for wall switches and porch lights overhead until they lined up for final position then droped them down the wall, thru a channel cut in the rigid foam insulation.

Oh, with-out the rigid foam, plywood has just about zero R-value.
I'm sure to get a bit of heat over that one, but if you are in an area where your going to get condensation, or have wide temperatures within your camping season, "Insulate", I camp all year round but I'm a desert camper for the most part, in So Cal, so Hot, Cold is part of year round camping, snow and rain come in when in the mountains or we head for a gathering somewhere EAST of us.

my walls ceiling and floor even my hatch and bulkhead seperating cabin and galley is insulated

Will do it again on my next build.

[bobhenry]

Billy

my walls ceiling and floor even my hatch and bulkhead seperating cabin and galley is insulated.

Will do it again on my next build.

Damn I knew I forgot something .............

the ceiling

[bobhenry]

1/2" plywood has an r value of .64 about the same as house wrap or visqueen. 3/4 foam is 4.96 or just under 8 times better than the plywood.

When I built the barn I had 2 1/2" wall studs so I was able to install an inner and outer layer of 3/4 and a 1" air gap. I created the gap by ripping some 1/2 foam strips. This creates a void much like an insulated window. My theory ( no matter how flawed ) was by minimizing the actual contact I might get less transfer of heat or cold thru the foam itsself.

Hint tooth pics hold the layers in place real well

For the floor I placed 2 layers on the sub floor and floated a 7/16 floor over it then carpeted. Yes I lost a fuzz of headroom but my butts warmer.

[Billy K]

Sorry bobhenry, the 'treasurer' says, no....

So, (out to in) 1/4"ply - 3/4"ply - 1/8"ply; would make a sufficient wall then? Insulated 3/4.

And, the biggest reasons for plywood vs 1x2; is wasted time and added work?

[Changer]

Was talking about this at the office today and my boss says I am too terrifying to be allowed loose with any kind of power saw and that framing is much safer.

If only I could make a frame out of PVC and just fiberglass it. I can DO that kind of building.