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I've been scouring the posts here to make my decision on wall covering and insulation. I've decided on a thin flooring material mounted horizontally for the wall covering, simple. 

As for the insulation, I hope to be following fairly decent weather, but after living in Kansas all my life, I realize the temps can change in a few hours from uncomfortably hot to uncomfortably cold. (or the other way around) I believe, due to the small amount of space available for insulation in a van, your just not going to accomplish a whole lot, and you'll be relying more on your method of heating, cooling & ventilation for temp. control.  

If I'm too hot, I'm hoping a good roof fan, like a maxxair and a small portable FF will cool me off enough, otherwise, I'll either start the van and sit in front of the AC or just get out and seek a cool spot. I'll be carrying a tent & hammock too.

If I'm too cold, I will first start with layering clothing, use blankets, (wool or space). Then if it's too cold fire up the Mr. Heater, little buddy. 

MY concerns & thoughts on insulation, vapor barriers et al.  - 
The insulation I'll "most likely" need, will be for aiding in cold weather. In the position of a vandweller, I believe it's easier to make your living space warmer than making it cooler. Heat from propane is easier than AC from solar. 

I've read many posts about layering, air gaps and vapor barriers and my main concern would be capturing moisture and growing things in my walls. With the small space involved in a van, once you fire up the heater, it usually needs to be on low, and it will still get plenty warm inside, provided you don't have giant air leaks. You will also be adding condensation from the heater & your breath. Running some sort of exhaust fan or dehumidifier would help, at the cost of how much elec. storage you  have. 

MY Plans on insulation - PLEASE POINT OUT MY MISTAKES NOW, I DON'T WANT TO SPEND MONEY FOOLISHLY FOR NO RETURN.  Confused

I'm thinking about bubble wrap against the van skin, with a layer of polyiso, held in place with aluminum tape, but not sealed air tight. My wall covering would also not be air tight and I'd run my roof vent or small DH to evacuate extra moisture. 
MY plans are to follow the fair weather, but I know I'll get caught in cold weather occasionally and want to be prepared. I'll drive to a warmer spot ASAP.  I REALLY don't want MOLD in my van walls.

I'm wanting to go to Lowes today or tomorrow to start my purchases and install.
"I'm thinking about bubble wrap against the van skin, with a layer of polyiso, held in place with aluminum tape, but not sealed air tight. My wall covering would also not be air tight and I'd run my roof vent or small DH to evacuate extra moisture."

From what I've read and understood so far, bubble wrap against the van skin doesn't serves any useful purpose.  But it does between windows and Reflectix.  Is that correct?

Why not apply the Polyiso directly to the walls, using two layers of the 1/2"?  That shouldn't take up any more room than Bubblewrap + a single layer of 1/2" Polyiso.

About the humidity... Is this REALLY a problem???  Doesn't a person living in their van usually have the door and/or roof vent(s) open during the day for venting, unless it's too cold?  If you're chasing the warmer weather, how much humidity is actually likely to build up?  I'm thinking not much.

I sure hope I get all of this straight before I have to do it myself!
I am not a fan of vapor barriers. I think that nothing is perfect and getting moisture on the wrong side of the vapor barrier can do more harm than good. I also prefer insulation that will allow any moisture to wick it's way to where it can evaporate. I am probably in the minority on this issue.

I bought a conversion van and have been working on the mechanicals, (tires, paint, trans and carb rebuild). Next step will be to redo the interior. I don't know what the factory used if anything for insulation. If there was one perfect insulation, there would only be one type of insulation. So weighing all the variables, I am leaning towards recycled denim if I redo the insulation. What sent me on this path is this video. https://www.youtube.com/watch?v=aepHKxVPMNo
He does a whole build series of videos.
Thanks very much DB1954 & TC!!

The denim sounds very innovative, I'd love to see how it comes out.

After more reading & shopping around plus your kind replies, I think I'll stick with 2 pcs. of 1/2 polyiso, then my wall. I was thinking the bubble wrap would give a little air gap, but REALLY, I'll probably be in fair weather as often as possible. I saw a video on YT with 12v dehumidifiers, less than $100. If when I start my travels I feel I need one, I'll get it then.
Thanks again you 2, much appreciated.
(10-09-2016, 08:33 AM)Gadget728 Wrote: [ -> ]I'm thinking about bubble wrap against the van skin, with a layer of polyiso, held in place with aluminum tape, but not sealed air tight. My wall covering would also not be air tight and I'd run my roof vent or small DH to evacuate extra moisture. 
MY plans are to follow the fair weather, but I know I'll get caught in cold weather occasionally and want to be prepared. I'll drive to a warmer spot ASAP.  I REALLY don't want MOLD in my van walls.

Bubble wrap is ONLY used if you're going to be installing a radiant heat barrier. Polyiso is an insulation product not a RHB so there's no point in putting it in under polyiso.

In 40 years of owning vans, being around vans, travelling all over the continent with van clubs and living in 4 season weather where the vans were subjected to freezing temperature overnight and heated while being driven that afternoon, I HAVE NEVER ONCE seen a case of mold inside the van caused by a build up of condensation from heating, cooking or just general living conditions.

We used to go winter camping with the vans where we had 0 F temperatures outside and warm cozy temps inside - 40 years ago all we used was pink fiberglass because that was all that was available - no mold problem...nada!

The only time I've seen wet insulation is from leaks - around RV windows, at roof vents that weren't sealed and where holes were put in roofs for various purposes and not sealed properly. I found mold in the pink insulation used in Lady Arabella by the PO, it was where he'd drilled holes in the roof and not applied any sealant at all. But then I also found dead animal bodies and a lot of other nasty stuff hidden in the pink insulation as well!!!

IMO, don't worry about mold, the chances of a problem are less than you winning a lottery even if you do buy a lot of tickets.
Thanks Almost There - I skipped the bubble wrap and bought some 1/2" sheets of polyiso today. i'll post pics when the walls are up.