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Old 08-21-2018, 08:54 AM   #1
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1956 22' Caravanner
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Insulation question Prodex

Without opening a can of worms...I noticed now that there is a 10mm prodex product that they are advertising. Would this have any advantage over the 5mm besides being thicker? Maybe time savings ? Only have to use one layer.

This is a question that deals only with prodex...I have read the volumes of posts on insulation of Airstreams so we don't have to rehash that please...
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Old 08-21-2018, 10:01 AM   #2
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I’d think being thicker would have a better R-value.

Do you plan to insulate with anything else other than the Prodex?
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Old 08-21-2018, 10:38 AM   #3
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Speaking of a can o' worms -- one of these days, I should get a dozen or so large cans, put in samples of different available and price-efficient insulation types along with a thermometer, place under a heat lamp and in a freezer and record the results.

To make it more relevant, i should rivet a couple of AL stringers to the outside skin and expose them directly to the interior.

My hypothesis is that the type of insulation will, in the end, make little difference as long as the AL ribs are conducting directly to the interior. That hypothesis awaits experimental verification.
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Old 08-22-2018, 07:55 AM   #4
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Quote:
Originally Posted by skyguyscott View Post
My hypothesis is that the type of insulation will, in the end, make little difference as long as the AL ribs are conducting directly to the interior. That hypothesis awaits experimental verification.
I have no opinion right now if you would be right? I was thinking of putting my shell out in the sun(florida-hot). Insulating a section, cleco a panel on and do a temperature check on the insulated part vs. non. That should tell me if there is any great difference in the surface temperature. Don't you think?
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Old 08-22-2018, 08:10 AM   #5
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Suggest considering 3M Thinsulate(TM) automotive insulation or Low-E SSR as other options for insulating an AS.

Thinner reflective insulation products like Prodex, Low-E and Reflectix get their R-value from the air they trap in the space behind the product. Not much R-value by themselves. Generally speaking, R-value comes from thickness/depth.

Conduction does work against us in AS trailers and vans but insulating does make a difference. Just don't get too carried away with it. Thinsulate provides thermal and acoustic insulation so that's a plus.

All the best,
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Old 08-22-2018, 08:19 AM   #6
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Heat vs. Cold

Being in FL, you will understandably be more concerned with radiant heat from the sun heating the interior of your trailer, in which case, insulation that does best at reflecting radiant heat would be most important.

However, in my experience, such insulation is not particularly great at retaining interior heat in colder environments. This scenario is where the ribs conducting the exterior cold into the interior really shows up.
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Old 08-22-2018, 09:15 AM   #7
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Terry, Good points made. There’s just so much you can do with an inch and a half cavity. We used the 5mm Prodex because that was what they had. Two layers with a spacer and 1/2” Foamular as a cap. I think that may have been overkill. Like mentioned, thermal transfer is important. I went ahead and painted the cavity side of the interior skins with Hy-Tech Ceramic Paint Additive in Zinsser. We also painted the ribs and stringers. This stuff was reasonably priced, but don’t know if it will do as stated. With your interior skins out, maybe paint the cavity side of the exterior skins with a thermal paint. I think the tape on the ribs would be a better thermal break, but I wanted paint so I could line up the old rivet holes for exact fit. I think I would lean toward the 10mm Prodex as one layer. You could attach it with the 3M 77, run your wire, then cap it with some Roxul. Test that in your Florida lab. One thing we ran into was the varied thickness of the end cap cavities. There was a hand written note on the inside of one of the end caps that read “Alex, don’t give up”. Well, Alex may have been a newbie because the end cap cavities varied from 3/4” to 1-1/2”. There are no ribs or stringers to gauge. So, be aware. Good luck, Bubba
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Old 08-22-2018, 02:06 PM   #8
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We recommend 3M 90 high temp spray adhesive for attaching insulation in vehicles. The 77 spray adhesive does not hold up well to heat.

The 90 spray adhesive also now comes in a low VOC version.

All the best,
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Old 08-23-2018, 07:01 AM   #9
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A different view on Insulation

Quote:
Originally Posted by Bubba L View Post
Good points made. There’s just so much you can do with an inch and a half cavity.
This is another interesting read for those who want to know more about insulation and were afraid to ask... https://gnomadhome.com/van-build-insulation/

I realize that a van build is different...however I like the way this guy broke down the whys and what he recommends. Not saying its all correct just saying it was presented well.

It amazing how you find things...I was doing a search on thinsulate and this thread popped up...
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Old 08-26-2018, 07:40 AM   #10
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Another view on Radiant Barrier

I found another site that explains radiant barrier really well...If true it kind of shoots down the prodex and bubble products.

www.RoofingFoil.com
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Old 08-28-2018, 10:02 AM   #11
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This site also has a good explanation of r-value and a comparison of various insulation types: https://www.parkedinparadise.com/insulate-van/

It's my understanding that without a sufficient air gap products that block radiant heat like reflectix aren't going to do much in a wall. Although they do work really well when covering windows. That's explained more in-depth with a good diagram here: https://www.parkedinparadise.com/van-insulation-heat/
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Old 09-03-2018, 02:21 PM   #12
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im new with airstreams and maybe this has been dealt with before but how would spray in foam like that used in new homes put in while interior panels are off during restore

this would also create a water seal on the inside at the skin joints so would seal out future leaks and give the aluminum outside skin a little more firmness against dents
any pros or cons

thanks
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Old 09-03-2018, 09:57 PM   #13
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If you use the search feature in this forum, you will find hours of interesting reading on spray foam insulation.

A quick summary: old spray foams turned to dust, newer formulations said to be able to handle flex. Foam may be best, most cost effective insulation BUT what if you need to replace a panel? May be a pain. Will it trap moisture against skin and accelerate corrosion? Depends on how it is applied. Said to add strength to shell. Pain to remove if ever need to remove it. What about running new wires/pipes, etc.? Maybe add conduit before applying foam.

There does not seem to be a consensus on this topic, but rather, several competing schools of thought on the matter, as well as many different opinions on the best material, hence the OP's reluctance to open a can of worms. And you still have the rib conduction issue.

You can quickly loose a good night or two reading about just this one topic here.
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Old 09-04-2018, 06:17 AM   #14
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I used spray foam. I like the insulating properties but it is not 100 percent waterproof. It's expensive and time consuming. If I had to do it again I'd install rmax polyiso found at box stores. I did place a thermal barrier on the ribs. This made the biggest difference. These campers are only 1.5 thick so you can only do so much. I don't regret the spray foam. My heart was set on it but I tend to learn from experience and not advice. Pm if you have questions.

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