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View Full Version : Radiant barrier in a metal cargo van.



Basement Yeti
03-23-2011, 11:16 PM
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
03-23-2011, 11:35 PM
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
03-23-2011, 11:53 PM
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
03-24-2011, 12:42 AM
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
03-24-2011, 05:46 AM
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
03-24-2011, 06:47 AM
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
03-24-2011, 06:55 AM
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
03-24-2011, 07:39 AM
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
03-24-2011, 08:00 AM
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
03-24-2011, 08:40 AM
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
03-24-2011, 09:12 AM
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.

Basement Yeti
03-24-2011, 09:24 AM
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
03-24-2011, 11:00 AM
http://www.radiantbarrier.com/faq.htm

southpier
03-24-2011, 11:03 AM
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
03-24-2011, 02:27 PM
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.

Basement Yeti
03-24-2011, 06:56 PM
http://www.radiantbarrier.com/faq.htm

That website just confirms what I read. Radiant barrier requires an air gap or it's moot.


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.

I'm not up on sticking wood to the ribs and screwing my paneling into the wood, seems not as secure. There has to be some way to combat this, by coating the screws in something.


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.

The stuff seems thick, if I used it I don't think I'd have room for insulation.


I've been doing some more research and there are vegetable based expanding foam insulation. I wonder if they'd work in an application like this.

Bogo
05-31-2011, 08:45 AM
I've been doing some more research and there are vegetable based expanding foam insulation. I wonder if they'd work in an application like this.
When choosing a foam, glue, or other material for use right up against the skin of a vehicle, make sure it can handle 250F. The exterior skin of a car can easily get close to that temperature on a hot sunny windless day. Not many foams are rated for that high of temperature.

Token
06-11-2011, 06:47 PM
For some reason I'm not getting a visual on all this, but for insulating, maybe try some foam board used for prewrapping houses before putting aluminum siding up. If it's to ugly by itself you could wrap/cover it with a light cloth material.. Or even hang up material like curtains over it and give it a Turkish tent feel inside..

FYI, that foam board cuts very easily and neatly with a HOT soldering gun.. Not so much with any other way you can think to cut it..

Bogo
06-12-2011, 04:07 AM
I've successfully cut foam with a thin bladed cheap knives. The trapezoidal mat knife blades work for up to 3/4" thick, or if you flip the board over up to 1-1/2" foam board.. You want one that has the same bevel on each side of the cutting edge. That is so it tracks straight. First make a light 1/4" deep cut to start the cut and cut the covering, then gently tension the foam to open the cut and cut the same line to deepen it about 1/2" or so with each cut. I always cut along a straight edge that is set on top of the foam.