Radiant barrier in a metal cargo van.

Basement Yeti

Explorer
Shortly I will be insulating my Chevrolet Astro van. I plan to paint the back first where the metal is scuffed up and gouged. Before I add my cotton insulation I want to add radiant barrier. But I have a few questions I am hoping you guys can help with.

Should I go with single sided reflective facing outwards radiant barrier or a double sided radiant barrier that faces inward. I know inward facing radiant barrier will help in the winter, but won't heat coming in from my windows and windshield get trapped inside in the summer too?

Secondly I am stumped on how to adhere the radiant barrier to the walls. I know there are some eco friendly spray adhesives but I would prefer a mechanical method of installing the radiant barrier if possible, would drilling it into the walls with self drilling screws work?

How about if I install it onto the backside of my wood paneling facing outward over the cotton insulation. Would it reduce the effectiveness of the radiant barrier?

Thanks.
 

southpier

Expedition Leader
ideally the barrier will have no penetrations. that being said, it would be an easier application if you could cut the panels and then attach (3M spray) the vapor barrier to it. i was always led to believe the barrier goes on the warm side of the insulation. i don't think the material matters much as long as it is vapor impermeable.

if you can add a wood strip (even 1/2" thick) to the van's ribs with a strip of foam tape between it and the metal rib, and then screw your panels up with screws too short to penetrate the strip, you will have elimenated a cold bridge and source of moisture condensation.

please post progress pictures
 

Basement Yeti

Explorer
By vapor barrier you mean the radiant barrier, right?

So you are suggesting I attach my radiant barrier to the back of my plywood paneling with some adhesive spray, then attach my wood paneling to the van avoiding drilling into the metal ribs themselves.

I don't really see the point of the last step. I am trying to insulate as best as possible, not create an impermeable fortress. Does drilling through the wood paneling, insulation, and radiant barrier into the metal ribs do something I am unaware of?

Why not just get a staple gun and attach the radiant barrier to the wood paneling that way, then just drill it directly to the metal ribs?

If I am going to go through the hassle of gluing it to the plywood panels I might as well glue it directly to the sheet metal, right?
 

Basement Yeti

Explorer
I've been doing a bit of research on radiant barrier. I assumed radiant barrier would work in my application because I saw a lot of van dwellers using radiant barrier in their conversions. Radiant barrier does not work without an air gap. Plain and simple.

The way I was planning on using it would be an utter waste of money. Gluing it to the wall and the smooshing the insulation and plywood paneling over it would actually make my van warmer.

I've been looking at foil faced bubble wrap that has it's own air gap recently but I need to do some more research. If anyone has any info on this stuff feel free to chime in.
 

NeverEnough

Adventurer
You might want to check out a product called Insul-tarp. It is a radiant barrier Designed to work without an air gap. It is cost effective And can be sandwiched With other insulation.
 

Basement Yeti

Explorer
You might want to check out a product called Insul-tarp. It is a radiant barrier Designed to work without an air gap. It is cost effective And can be sandwiched With other insulation.

Seems like it's designed to be used under concrete. Not sure it would work for my application.
 

chasingdreams

Adventurer
At Lowes they sell spray foam called "Froth-Pak". I used it in 2 of my company vans. Up here in Alaska we can get some seriously cold temps. Use duck tape and some masking for anything you dont want foam on. Be careful because the the foam expands alot..... a little goes a long way. The kit runs a couple hundred bucks but it is WELL worth it. Once your done foaming,...trim off any excess and install any interior panels that you planned on.
 

Basement Yeti

Explorer
Well, I've already got insulation. Plus, that stuff isn't intended for use on vertical surfaces.

I do wonder if I need some kind of vapor barrier though.
 

chasingdreams

Adventurer
Well, I've already got insulation. Plus, that stuff isn't intended for use on vertical surfaces.

I do wonder if I need some kind of vapor barrier though.

We must be talking about 2 different things..... That foam is designed to go anywhere.... vertical, horizontal, overhead, etc. It's primary application is residential. It's not like the little cans of "great stuff" that takes around an hour to cure. The stuff I'm talking about is cured within minutes of being sprayed.
 

Basement Yeti

Explorer
Hm, maybe I pulled up the wrong product when I searched.

This polyethylene expanding foam acts like a vapor barrier too, because it doesn't hold moisture like cotton and fiberglass batting, right?

I already bought my cotton insulation, even if I didn't the toxicity of this stuff is a concern. It out gasses chemicals for such a long time. I wish they made more eco friendly versions of this stuff, it'd be ideal.
 

LukeH

Adventurer
From experience, what you
REALLY DON'T WANT is for the humid interior air to reach the outer metal skin. The vapour condenses, runs down and saturates your fibrous insulation. After a few seasons this ends up mouldy and eventually smelly.
Unless of course you live somewhere really really dry and never camp in cool weather.

Sealing off the tinwork completely is of course impossible so using an insulation that doesn't absorb water is really your only option.
You can project a sort of spray foam onto every surface, or bond panels of polyurethane foam inside the body.
It's worth doing this really well, because you're not going to want to redo it once the interior is built.
There's a stack of info on the SBMCC forum, ok it's English so the product names aren't going to be the same; but the experience of van conversions for crappy climates (uk) is invaluable.
That stuff that Chasingdreams used in Alaska really sounds the business, if it works in those extremes it's probably worth the investment.
 
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Basement Yeti

Explorer
Yeah, reading up on this I am realizing what a problem it might be. The problem with this spray foam insulation is just how much it out gasses, I am just not cool with that.

Couldn't I just install a radiant barrier over the insulation?
 

southpier

Expedition Leader
By vapor barrier you mean the radiant barrier, right?

So you are suggesting I attach my radiant barrier to the back of my plywood paneling with some adhesive spray, then attach my wood paneling to the van avoiding drilling into the metal ribs themselves.

I don't really see the point of the last step. I am trying to insulate as best as possible, not create an impermeable fortress. Does drilling through the wood paneling, insulation, and radiant barrier into the metal ribs do something I am unaware of?

Why not just get a staple gun and attach the radiant barrier to the wood paneling that way, then just drill it directly to the metal ribs?

If I am going to go through the hassle of gluing it to the plywood panels I might as well glue it directly to the sheet metal, right?


research "thermal bridge". if you screw from a warm place (finished interior) to a cold place (steel body rib) there will be condensation on your screw heads. you need to incorporate a thermal bridge to eliminate this.
 

NeverEnough

Adventurer
I have used insul-tarp on metal vehicle roll-up doors on two occasions and it worked great. I've also used scap pieces under foam sleeping pads for years when snow camping and it is very effective as a vb and reflective insulator.
 

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