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Old 02-28-2019, 12:16 PM   #1
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question on insulation and radiant barriers

Hi, working on a stepvan conversion.... hopefully that doesnt disqualify me from this forum as so much of what we have to do to our vehicles is the same. Ive gathered a lot of knowledge from this forum so far as it all crosses over.

I had a question about cold weather insulation that I was hoping someone had experience with. Im currently living in a warm climate so very little experience with cold... but will be transitioning with vehicle to very cold environment soon. I'm trying to upgrade insulation starting with ceiling which is all sheet aluminum supported by 1.5 inch thick ribs at 3 foot intervals. Im planning on installing a wood stove as my primary heat source for simplicity as tapping into fuel tank with a webasto or using propane is something I dont want to deal with.

Presently my plan is to use 1.5 inches thick foil faced polyiso glued to roof and taped at seams and then facing that again with thick aluminum foil so I dont have to stare at ugly lettering embossed on insulation sheets. I was wondering mainly if the foil idea would add a significant amount of warmth by functioning as a radiant barrier reflecting heat downwards off the ceiling? Is a reflective radiant barrier like this effective in the cold (albeit maybe a bit ugly) or should I just go with a more traditional ceiling finish because this radiant barrier wouldnt do diddly squat?

Anyone have experience with this?

As for walls, those are presently uninsulated as well. Im mainly concerned about condensation building behind them so was considering 1.5 inch thick expanded cork insulation which has some permeability / breathability.

So cork walls and aluminum ceiling....unique look for sure...function over form though is my mantra

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Old 02-28-2019, 12:55 PM   #2
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I had considered a step-van to convert as well. Likely a lot easier given the empty shell to start and the nice square corners.
Many folks here are using either rigid foam or spray foam for insulating due to its high R value and ability to reduce condensation issues. I've been reading about the environmental concerns of the Poly-iso type foam, so the cork product you mentioned has me intrigued. I wonder about the permeability, as it looks to be higher than foam. I don't know how much of a concern that difference is. Less permeable is better so you don't develop condensation on the inside of the metal. I love the idea of it and it could be used as the finish surface as well. Plus the noise reduction factor would be huge, I imagine.
As for your ceiling, I think those foam panels usually only have markings on one side, so you could install the advertising side up and avoid the extra layer of foil. I doubt another foil layer would aid anything.
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Old 02-28-2019, 01:34 PM   #3
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Wood burner stoves are very efficient, you'll only need a tiny one for that space without being overheated. What model did you have planned?
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Old 02-28-2019, 01:49 PM   #4
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Looking at cubic mini....either grizzly or cub. Leaning towards larger grizzly as it would allow slightly longer burn times to get me through night. Im heating less than 100 square feet though....

As for cork, i have no experience with it other than some samples from thermacork. Its pretty hydrophobic and very fire resistant and has as low permeability rating and a decent r value...approx 3.5 per inch I believe. Trapping moisture behind insulation is a worry for me so I was thinking a breatheable wood surface with low perm rating would keep most airborne water vapors from cold aluminum skin but if it happened to get through would also allow it to escape. In some ways the cork could act a bit like a humidor keeping a more stable humidity level through dry winter months with wood stove....thats all just conjecture at this point though.

Mostly though Im interested in radiant barriers for containing heat. I know they put foil inside some performance clothing to reflect body heat. And radiant barriers are effective at keeping heat out of cars...windshield screens and such...i cant think of why they wouldnt work to keep heat contained though...taking the ugly factor out of the picture, would lining the interior wall surfaces of a house in reflective foil have an effect on containing heat radiating out through walls?
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Old 02-28-2019, 06:04 PM   #5
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I would think about using mylar-based reflective film (available on instead of aluminum foil. But I would also use 2-3" thick instead of 1.5" on the ceiling.
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