foil insulation?

[Creek Kid]

Wondering what kind of insulation to use for a semi-permanent with plywood walls. I want to keep weight down so am leaning towards 3/8" plywood. Am wondering if I can use foil/bubble wrap insulation or will it condensate too much. Would I gain any R value at all if I put it on the exterior? I plan to have bunks so don't want to be dripped on in the middle of the night. trying to stay in the 1-1-1/2' thick wall range. Any suggestions?

[Creek Kid]

Let me re-phrase my question. Those of you who have shacks made out of plywood (whether they are skid houses or wheeled) and are insulated, did you use a vapor barrier? Do you get condensation on the ceiling? With trying keep weight down I want to stay away from 3-4" walls w/insulation in the middle + vapor barrier. How are your walls & ceilings constructed?

[MNCrappieFlop]

I get a lot of condensation, put in a vapor barrier on one of my houses but on the other one didn't...and go through twice the heat.

Lesser of two evils?

[cavalierowner]

I built a little 4 x 8 skid house for my Mom and Dad a couple years ago. I had to keep the weight down, so I used 1/2" plywood with 2x4's @ 24" o.c. laid flat and spanning the short dimension to support the floor (2x6 skids). The walls are 1/4" plywood run horizontal with 2x2's in the corners and at all the joints. The roof is also 1/4" plywood with 2x2's @ 24" o.c.; the roof slopes 4" in the 4' dimension. Everything is glued and screwed together. We insulated the walls and roof with 1" extruded polystyrene (R-5) and glued it to the walls and ceiling with no vapor retarder. This house is SOLID; we could roll it down a hill with no damage. I won't go into how I know that!!

This house replaces the last one they had that was almost identical and lasted almost 15 years before the d*** woodpeckers got to it! The best thing is that there was NO condensation on either house. I really, really can't tolerate condensation! As for weight, I originally calculated that the house would weigh around 300 pounds and that's probably a pretty good estimate. There are 7 sheets of 1/4" plywood in this house; if I had used 3/8", it would add roughly 100 pounds.

[Gus]

I have an 8x10. I used 2x3 studs on their sides 24"oc. 1/4" plywood siding (would do 3/8 if I did it over) Since I laid the studs sideways I used 1.5" sheet insulation that sits perfectly in between the studs. I left the insulation exposed, did not vapor barrier. Have no issues with condensation. I use a buddy heater and on low it'll keep it over 75 unless you crack a window.

My build was supposed to be light weight. It is pretty light, my guess is right around 600 pounds. Easily winches up onto my 8x10 snowmobile trailer.

I'm going into year 4 now. So far it's holding up well except for the 1/4" ply. That was a cluster from the beginning. Driving rain for 4 days before I could get some paint on the 1/4" really made a mess out of it. I believe you can get 3/8" cdx where the 1/4" I used may not have been "x". I took that gamble and lost. Lesson learned.