Its just an idea but if you used 2x2 studs screwed to the walls on 16 in centers then pick up one of the do it yourself sprayfoam insulation cans and spray it yourself and save a bunch of money that way then decide what you want to cover the studs with like 1/2 in plywood so between the 2 in of foam and 1/2 plywood should be a big R factor insulation in there plus you can prewire and plumb your walls prior to spraying and theres lots of how to videos on youtube and either paint the plywood both side before mounting to the walls and you wont have any sweating in the wall problems like most of these builds wind up with !The weather has cleared and I'm back at it in the morning. No wind, temps in the 90's, 98% humidity, and mosquitos are already sortieing their attacks.
I'm at a point where I have to make a call that will add a good chunk of expense I was trying to avoid, but I know I'll regret not doing it.
The M1079 box is shite when it comes to insulation. Like most all military shelters, it's dreadfully poor insulation combined with the fact that it's one big aluminum thermal bride make it just as hot (or cold) on the inside skin as the outside. It consists of 2" of foam with aluminum skin on each surface. The framing is aluminum and everything is pretty much just attached toghter metal-to-metal.
If you're not familiar with thermal bridging, it's basically metal-to-metal transference of heat (or cold). Metal is a great conductor of heat, as we all know (just stick your hand in a hot cast iron skillet to prove the fact). Thermal bridging can be avoided by introducing a layer of non-heat-conducting material into the manufacturing process (like a layer of wood, etc). The military overcomes these design flaws by using 2-tons of house air conditioning to cool 100sq/ft box (or a warehouse blast furnace to heat the same).
Anyway.....
I'm debating adding a layer of insulation onto the walls and ceiling and bringing the new surface out 2". The height loss won't effect anything but losing 4" or habitat width is why I shifted away from this idea in the first place. But sitting in there tonight making note of where everything is bolted together (getting ready to gut it all for paint), I realized that four inches less horizontal space wouldn't really be an issue.
I figure I can use 2x2 as studs and secure it all with rivnuts and the existing taps into the main frame (where the steel wall skids were attached). I need to decide if I want to cover the wire tray or leave it accessible (I figure covering it would look best and I can leave a few small sections accessible so I could always blow a fish line thru if more wire runs became needed). Then there's the matter of insulation and paneling choices that I can afford. In a perfect world I'd be rich and insulate with something 100% fireproof and then panel with StarBoard (but I'm poor and I can't afford $250 a sheet for ANYTHING).
What I can afford is whatever Styrofoam-based or fiberglass insulation is on sale at Home Depot covered with $25 /sheet PlasTex (which I used in the shower). I kinda hate the looks of the stuff, but it's what I can afford. I favor plastics as the humidity down here eats any of those particle/MDF/glued-together/coated pressboard materials (like Beadboard, etc). I'd prefer something that's already available locally and I've looked in the past and there's really not much of a choice that is 1) cheap, 2) plastic, 3) available locally.
Or just leave things as they are....
But if I'm gonna do it, I need to go get materials tomorrow because if I push this project deadline much further I'll be too old to use the damned thing.