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I'm not here to tout or sell a product..... Yet ;)

I've been in the trades for 30 years and have torn apart many types of insulation and in thousands of buildings. I'm NOT an expert in insulation.

Since I will be starting my build soon I thought I would share journey as to how I'm going to insulate my build.

A good place to start....

http://en.m.wikipedia.org/wiki/R-value_(insulation)

I've looked into spray foam and it's a wonderful product for many things but I don't think in my van that it's the best for me. I just don't know how it will hold up to the twisting of the chassis.

I'm going to put this one the floor

FOAMULAR® Insulation (this is the pink Owens Corning boards)

All Foamular XPS products are R-5 per inch of thickness except High-R CW Plus that is R-10 at 1-3/4", and R-12 at 2 1/8 " thick.

I will be 1" or less in thickness since I'm building on a 136" low roof.

Todd
 

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That's the same stuff I used on my walls (2") for the same reasons!
 

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Just keep it dry which should not be a problem as it does absorb water. It also will let vapor out so it can dry but slowly. It's good for 25 psi support which is a lot so you can walk on it. When installing it don't get down on your knees as you can deform it since your knee is rounded and your weight may exceed the 25 psi. It glues well and if held in place is quiet, If not it squeaks as it is moved around which may not be a problem when you put on the brakes. Ha Ha! I'd think an inch R-5 plus plywood R-.75(?) should be enough. If you want to go lower try Dow Formular Tuff R. R-6+ per inch so 1/2 inch foil faced might do. leave the channels empty to gain a bit on the foil to air surface.
 

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Speaking of insulation, I learned some things today.

I decided to use polyiso in the ceiling. I measured about 1.25” clearance, so I bought 1". Unfortunately, I hadn't accounted for those various welds. After totally destroying one board trying to make it fit, I realized that a 1/4" shim will make the 1" board a perfect fit. This will be about R-6. I will attach the polyiso to the ceiling board, not to the van. It makes more sense to me that the insulation be attached to the surface I'm insulating.

To help seal, I put closed cell foam tape on the van surface all around the foam board. This is the stuff that normally goes between truck and camper shell. I will also use aluminum tape.

The slope on the ceiling ribs is 20°.

For the ceiling, this polyiso is within $25 or so of Hein's thinsulate. I chose the polyiso instead because the tight clearance would not allow the thinsulate to expand to its full volume, thus R-value would be compromised.

I plan to use thinsulate everywhere below the belt line.
 

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I'm not sure I follow both your explanation and your reasoning. I can't say I have heard of people attaching the insulation to the panel they are attaching to the roof ribs. Is that you did? Usually the method I see is first you attach your insulation to the van ceiling, then attach your vapor barrier, and finally attach your ceiling panel.
 

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I am in a quandary. The adhesives seem to be attachment upon contact with no open time for adjustments. If I cut the panel for a tight fit, which seems the logical thing to do, no way could I just lay it in perfectly, particularly above my head.

Suggestions welcome.
 

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I am in a quandary. The adhesives seem to be attachment upon contact with no open time for adjustments. If I cut the panel for a tight fit, which seems the logical thing to do, no way could I just lay it in perfectly, particularly above my head.
Suggestions welcome.
I'm not sure why you can't get a perfect fit then put the adhesives on and return it by aligning one edge, but I guess you have tried that and it didn't work. BTW I see jostalli mentions vapor barrier and I'd caution against that. The polyisocyanurate (Dow Tuff R?) has aluminum faces which might benefit from being spaced a bit from the liner side. I'd want it in contact with the van roof to decrease the possibility of condensation on the vans tin. 1/2 inch or 3/4 inch might be as effective as 1 inch used that way. Perhaps change to that and save the 1 inch for the upper walls? R-6+ air space should be enough in the walls and R-5(3/4")+ air space in the ceiling is about all that can fit anyway? I hope you are capturing this on pictures to help us? Thanks for past and future posts.
 

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"The polyisocyanurate (Dow Tuff R?) has aluminum faces which might benefit from being spaced a bit from the liner side." Please explain. Are you suggesting I not have such a tight fit?

Perhaps cut the board to fit between the welds, then fill in with something else over the ribs?

I admit I'm overthinking this, but I get one chance to get it right.
 

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I am in a quandary. The adhesives seem to be attachment upon contact with no open time for adjustments. If I cut the panel for a tight fit, which seems the logical thing to do, no way could I just lay it in perfectly, particularly above my head.

Suggestions welcome.
Hot melt glue guide blocks on two corners east south south west, on the north end just east west sides. If you need a third foot fasten a furr strip just to hold up the north end loosely.
 

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One thing I haven't seen talked about is squeak factor. When I walked through Home Depot and checked insulation materials, all of them could be made to squeak.
 

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Vapor barrier, 1 opinion for 1 against. Here's mine: yes.
We all know the problem, if the van skin temperature is below the dew point of the air next to it you'll get condensation. With a vapor barrier, you slow down the migration of water vapor from the van interior to the wall or ceiling cavities, keeping the wall cavity dryer than the van interior. However, any vapor barrier we put up will not be perfect, some water vapor will leak thru, we are only slowing it down. But if it leaks out it will leak both ways.

You're sleeping in the van, adding moisture to the air from breathing & sweating, the vapor barrier will slow down the moisture migration enough so the humidity in the wall/ceiling/floor cavity is low enough so there isn't any condensation. Next day, the van is opened up and the air inside is dryer, and the humidity in the wall/ceiling cavities be reduced too. If there isn't a vapor barrier that moisture will migrate quickly to the wall and possibly condense on the steel.
 

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Yes the rigid insulation must be installed so it can't move around. I am planning on installing it with Great stuff as an adhesive from my pro gun as the cans are a fools tool. For MsNomer I think you may be making your life too hard for an increase of R-1 and even that might be recoverable by using its foil face in concert with an airspace between the insulation and the liner. Try a bit thinner polyisocyanurate with foil in contact with the van so there is a 1/2" or more space to the liner? Use some bracing to push the rigid board right to the van roof, take a break while the adhesive works, then do another. Use the spray foam to fill the side gaps where it works best anyway. Remember this is a tiny volume we are insulating and the difference between R-5 and R-6 will not make a measurable difference in heating or cooling and both are going to be lots better than the 3/16 inch flexible sheets many are using. Just my opinion but backed with some experience in home building.
 

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I played some more with this sheet I had already ruined. If I trim it to fit between the welds, 1" fits fine and I can actually salvage this abused orphan. Then I can fill in around the edges. Much easier.

The John Manville polyiso I got at Menards seems to have shiny aluminum on one face. The other is white. Which way up?

Of course, only half the roof surface will be in contact with the foam. There will be gaps at the ribs. Is this relevant?
 

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Vapor barrier, 1 opinion for 1 against. Here's mine: yes.
We all know the problem, if the van skin temperature is below the dew point of the air next to it you'll get condensation. With a vapor barrier, you slow down the migration of water vapor from the van interior to the wall or ceiling cavities, keeping the wall cavity dryer than the van interior. However, any vapor barrier we put up will not be perfect, some water vapor will leak thru, we are only slowing it down. But if it leaks out it will leak both ways.

You're sleeping in the van, adding moisture to the air from breathing & sweating, the vapor barrier will slow down the moisture migration enough so the humidity in the wall/ceiling/floor cavity is low enough so there isn't any condensation. Next day, the van is opened up and the air inside is dryer, and the humidity in the wall/ceiling cavities be reduced too. If there isn't a vapor barrier that moisture will migrate quickly to the wall and possibly condense on the steel.
Two vapor barriers is a terrible mistake. We did it in home building in the 1970's and rotted out many a good home. Yes vapor will get into the cavity between the vapor barriers. And yes it will condense onto the van walls. With that LIQUID water between the two impervious surfaces it will stay there, and rust the van. Solution? One vapor barrier is all you CAN have so the condensate can revaporize when the van heats up and escape through the only surface it can get through, back into the van interior where it can be vented away. AND put the insulation in contact with the vans walls to have the dew point occur IN THE rigid insulation between its surfaces where the vapor cannot get (seal the edges and don't disturb the foil surfaces) that way there is NO vapor where the deep point is so NO CONDENSATE! This is a proven system in modern super insulated buildings (which I have built and it works). This is why a rigid foam that will not absorb water is needed and why foaming the van works and layers of loose fill like fiberglas only won't. Hey this is just one opinion. You let us know how your vapor sandwich works. I love experiments!
 
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I played some more with this sheet I had already ruined. If I trim it to fit between the welds, 1" fits fine and I can actually salvage this abused orphan. Then I can fill in around the edges. Much easier.

The John Manville polyiso I got at Menards seems to have shiny aluminum on one face. The other is white. Which way up?

Of course, only half the roof surface will be in contact with the foam. There will be gaps at the ribs. Is this relevant?
Both are foil I believe. Shiny side towards the living space. Oh I now see what you mean. Yes great stuff to fill those as an expanding glue. Fill 'em and brace the rigid sheet up against the ribs.
 

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I am in a quandary. The adhesives seem to be attachment upon contact with no open time for adjustments. If I cut the panel for a tight fit, which seems the logical thing to do, no way could I just lay it in perfectly, particularly above my head.

Suggestions welcome.
Hi,
I would try using Great Stuff, which is polyurethane insulation in a can, as the adhesive to glue your insulation panels to the wall/ceiling. The Great Stuff is both a good insulator and a very good adhesive that holds up to high temperatures.

The Great Stuff takes about a half hour to set, and during that time you would have to have some props to hold it up to the ceiling. The Great Stuff cures from the moisture in the air, so spraying a little moisture into the air before you apply the Great Stuff will make it cure faster. I would try to get enough Great Stuff on the back of each piece to form a continuous layer -- this will keep any moist air from getting into the space.

After the pieces are cured in place, I'd go around the edges with the great stuff to try to eliminate any area where metal shows. The Great Stuff is a vapor barrier and will prevent condensation on the metal as long as you cover all the metal.

If you have not worked with Great Stuff, be aware that if you get it on your hands (or anything else) you will be wearing it for a week -- once it cures its really tough to get off.
There is also a Pro version that is used with an all metal gun that makes application easier ($30).

Gary
 

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RD, I remember learning about the vapor barrier issue when redoing my shower, but keep forgetting that the van roof is the ultimate barrier. You are absolutely correct. So this says that if I use any board with impervious face to the ceiling, I must fill in the ribs with foam.

Can I spray Great Stuff in increments? Fill the ribs first, smooth it off, then stick on the board?

Argh!! Or maybe I should return the unused polyiso, order Hein's thinsulate and accept the lower R-value by maybe a third.
 

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If using Great stuff ,there is a chance of warping the outer panels
Spraying in cavities you must be careful..
 

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RD, I remember learning about the vapor barrier issue when redoing my shower, but keep forgetting that the van roof is the ultimate barrier. So this says that if I use any board with impervious face to the ceiling, I must fill in the ribs with foam.

Can I spray Great Stuff in increments? Fill the ribs first, smooth it off, then stick on the board?

Argh!! Or maybe I should return the unused polyiso, order Hein's thinsulate and accept the lower R-value by maybe a third.
The Great stuff is hard to get to stay up on a horizontal surface overhead but it can be done with a bit of practice. Buy a pro gun and the larger cans for it. Put down a drop cloth and have nitrile gloves and a cheap plastic rain poncho ($!) on. Hold the tip if the gun about 1/4 inch from the ceiling and perpendicular, adjust the gun for a smallish bead and 1/4+ fill the ribs quickly. You have 10 minutes or more to put up the foam and brace it. I'd leave it for an hour and fill the edges. With practice you will find this works fine. You know I think this is better than Hein's. Try for a complete fill when expanded This should wire better on the walls as no ribs to fill. Doing the rib fill with the great stuff first and slicing it away is worth a try but I suspect unnecessary. I haven't tried of course. Best.
 
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