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insulation and such and so forth
#21
(12-18-2017, 08:38 PM)bethiebugs Wrote: Would something like Reflectix work as a vapor barrier over the rigid foam but under the paneling?

As the ridged polyiso foam is already a vapor barrier in and of itself, then no additional vapor barrier is needed. 


What is note worthy, is to make sure that the is no gap between the metal and the first layer of polyiso. Like a gap created by any glue used to hold the polyiso towards the metal. 
To seal that "gap" (and to ensure waterproofing of the glue, so to speak), I recommend using tape at the edges of the polyiso.  So the tape also helps hold the polyiso towards the metal. 



Here is an example of something that is made windproof (and thus is also airtight and watertight) and will act as a vapor barrier, though it is not thought to be a vapor barrier. 
https://www.youtube.com/watch?v=h-m-tFcO...u.be&t=317

The red tape (and the glue on that tape specifically) is likely designed, so it is waterproof, even if the metal gets quite hot. 
Not all glue maintains it waterproof level of stickiness, when it gets hot. 


If you glue and tape the polyiso to the metal, the two becomes as one vapor barrier. 

My thinking is, that if you keep taping (and gluing) the next layers of polyiso, you maintain the 'only one' vapor barrier. As each layer becomes fully integrated into the "wall"/layer that is already there.  And no vapor will have any chance to get trapped (or find its way) in between the layers of the sandwich.  And thus it will appear as one solid wall. Even for vapor. 



If you decide to add refelectics (or another plastic barrier) right under the paneling, without gluing it up against the polyiso, then you have added a second vapor barrier. And have thus created a potential vapor trap. As is what happens when using two vapor barriers in the same wall/roof/space-divider-structure. 

A doubler barrier can be used, but you just need to be aware of it. And I recommend that you then take precautions, so it is possible to vent between the two barriers, when you have dry air to vent with. 


Only when you use "wooly" materials to insulate with, should you add an inside vapor barrier. And when you do, it is advisable of being aware of how to vent it, when dry air is available.
Or the metal is hot, and can thus be used to push any trapped moisture out of the insulation "trap", through those small holes mentioned earlier. 




There has already been some mention of "wolly" materials, like glasswool, rockwool, Insul-Bright. And here is yet another wooly material (thinsulate)
https://www.youtube.com/watch?v=SiiYOJ51...u.be&t=220

And finally, actual wool, could also be used. 
These past years, some kind of treated cardboard shreds have also been used, in hard to get to places, in buildings, here where I live. 


Each material has its own type of disadvantages. Like has been mentioned, glasswool  (and to some extend rockwool) may have particles that can break off, and it is not good to get those trapped in ones lungs. 

Some people might be allergic to the softeners used in the plastic (polymer) based "wool" products. 

Wool and paper are organic materials, and only when the right type of oil (or similar) is added, does it become resistant to the organic process of mold. The oil that is natural to wool, contains a natural anti-septic that will keep mold from growing (well, keep it at bay, for some time at least - typically at bay for some years, depending on how much of the oil evaporates from the wool, due to heat, and holes where it can escape its otherwise trapped life).  



Did this make sense to you?
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bethiebugs (12-20-2017)
#22
(12-19-2017, 10:20 PM)MrAlvinDude Wrote: As the ridged polyiso foam is already a vapor barrier in and of itself, then no additional vapor barrier is needed. 


What is note worthy, is to make sure that the is no gap between the metal and the first layer of polyiso. Like a gap created by any glue used to hold the polyiso towards the metal. 
To seal that "gap" (and to ensure waterproofing of the glue, so to speak), I recommend using tape at the edges of the polyiso.  So the tape also helps hold the polyiso towards the metal. 



Here is an example of something that is made windproof (and thus is also airtight and watertight) and will act as a vapor barrier, though it is not thought to be a vapor barrier. 
https://www.youtube.com/watch?v=h-m-tFcO...u.be&t=317

The red tape (and the glue on that tape specifically) is likely designed, so it is waterproof, even if the metal gets quite hot. 
Not all glue maintains it waterproof level of stickiness, when it gets hot. 


If you glue and tape the polyiso to the metal, the two becomes as one vapor barrier. 

My thinking is, that if you keep taping (and gluing) the next layers of polyiso, you maintain the 'only one' vapor barrier. As each layer becomes fully integrated into the "wall"/layer that is already there.  And no vapor will have any chance to get trapped (or find its way) in between the layers of the sandwich.  And thus it will appear as one solid wall. Even for vapor. 



If you decide to add refelectics (or another plastic barrier) right under the paneling, without gluing it up against the polyiso, then you have added a second vapor barrier. And have thus created a potential vapor trap. As is what happens when using two vapor barriers in the same wall/roof/space-divider-structure. 

A doubler barrier can be used, but you just need to be aware of it. And I recommend that you then take precautions, so it is possible to vent between the two barriers, when you have dry air to vent with. 


Only when you use "wooly" materials to insulate with, should you add an inside vapor barrier. And when you do, it is advisable of being aware of how to vent it, when dry air is available.
Or the metal is hot, and can thus be used to push any trapped moisture out of the insulation "trap", through those small holes mentioned earlier. 




There has already been some mention of "wolly" materials, like glasswool, rockwool, Insul-Bright. And here is yet another wooly material (thinsulate)
https://www.youtube.com/watch?v=SiiYOJ51...u.be&t=220

And finally, actual wool, could also be used. 
These past years, some kind of treated cardboard shreds have also been used, in hard to get to places, in buildings, here where I live. 


Each material has its own type of disadvantages. Like has been mentioned, glasswool  (and to some extend rockwool) may have particles that can break off, and it is not good to get those trapped in ones lungs. 

Some people might be allergic to the softeners used in the plastic (polymer) based "wool" products. 

Wool and paper are organic materials, and only when the right type of oil (or similar) is added, does it become resistant to the organic process of mold. The oil that is natural to wool, contains a natural anti-septic that will keep mold from growing (well, keep it at bay, for some time at least - typically at bay for some years, depending on how much of the oil evaporates from the wool, due to heat, and holes where it can escape its otherwise trapped life).  



Did this make sense to you?

I believe I understand to a certain point. So make sure the first layer of polyiso is completely up against the metal skin of the van, with tape around edges. Each subsequent layer of polyiso needs to continue this process to be as one "layer" or barrier. Any glasswool, rockwool or polyester/plastic fill could be used inside the ribs, if chosen, but not as important, and a thin layer of foam, thinsulate, or other flexible barrier could be used over the ribs if so chosen. Am I on the right track? I am planning to do this in stages, as I can, but want to get the basics set before I attempt sleeping in it in Kansas coldness! Thank you so much for your help!
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#23
There is no problem with gaps between the layers, including between the metal and first foam.

The vapor barrier concept is against gaps **through** the envelope, which allow heat to escape, radiant and conduction most drastically but also convection, infiltration between inside and outside the envelope.

Yes the ideal is complete encapsulation, all openings sealed except those used for controlled ventilation.

Difficult to achieve in a van, but strive for that and the closer you are to that goal the warmer you stay with least fuel consumption.

So no, a rigid foam sheet is not any vapor barrier, that requires either

continuous plastic sheeting, IMO 6mil or greater for longevity, or

spray foam sealing any gaps in between - in the plane or "dimension" perpindicular to the living space, think like a bubble, doesn't work with any holes in it.

Shiny doesn't matter unless pointing outwards at the sheet metal intentionally creating say a 1" air gap. In a van that space is best filled with foam, unless you already have 4", say R-30 for extreme conditions.
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bethiebugs (12-20-2017)
#24
(12-20-2017, 03:58 PM)bethiebugs Wrote: I believe I understand to a certain point. So make sure the first layer of polyiso is completely up against the metal skin of the van, with tape around edges. Each subsequent layer of polyiso needs to continue this process to be as one "layer" or barrier. 

Exactly.  
I suppose this could be referred to as the "one vapor barrier only" principle of insulating a van. Where all of the layers in the wall sandwich, is made as much as possible, into one solid wall.
And from the perspective of water vapor, this especially holds true.

So even if there will be a puncture somewhere, then vapor will still have a very difficult time to go anywhere. As the whole wall is "solid".


(12-20-2017, 03:58 PM)bethiebugs Wrote: Any glasswool, rockwool or polyester/plastic fill could be used inside the ribs if chosen

Yes they can.

The big question is always: what to do with those ribs, and doors, and corners? How to fill out their hollowness, so it is possible to limit the heat escape, at those locations.

All of the flexible insulation stuff, can be used to fill those holes in the ribs, edges and doors, where it is otherwise very difficult (or impossible) to place any ridged foam.


But once these woolly types of materials are introduced into the process, then it becomes necessary to think about those spots/locations in a different fashion, as the principle of "double vapor barriers" will typically become part of the process/implementation.


So it is not so much "over the ribs" as it is "in the ribs".

Once the ribs are filled with something, then it will typically become easy to cover the ribs, with the ridged polyiso boards, as one final layer covering the whole wall or ceiling.
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#25
(12-20-2017, 04:43 PM)John61CT Wrote: There is no problem with gaps between the layers,  including between the metal and first foam.

Hmmm... seems like we are describing two different principles of how to deal with vapor inside the sandwich of a wall. And especially what happens when it hits a barrier - that is colder than the dew-point of that particular vapor concentration. 

(12-20-2017, 04:43 PM)John61CT Wrote: The vapor barrier concept is against gaps **through** the envelope,

Yes, if there were only one envelope.  
As we are however dealing with a possible double envelope, and the stuff that happens if/when the inner envelope is breached (which basically is inevitable when used in habitats)  then my thinking is that the story changes a little.

And this is why I have tried to describe how one could possibly make only one solid envelope. And thus completely can ignore the talk of outer and inner envelope, as the outer envelope stretches all the way into the inner wall cover panels, and thus it becomes both the outer AND the inner envelope.

(12-20-2017, 04:43 PM)John61CT Wrote: So no, a rigid foam sheet is not any vapor barrier.

The polyiso boards are most likely close enough.
One could for instance take a piece and submerge it in water for a day or more, and then weigh it, to see if it has absorbed any water.
This test will show, that it is close enough to be considered a vapor barrier, when used to insulate a van.


If one were to seal the deal, so to speak, using a continuous plastic sheet, glued to the foam, and taped around the edges, then it would indeed improve the vapor proofing of the inner envelope. As any foam material, is likely to have breaches in the outer layer of "bubles" making up the foam board. 
The gluing is in order to maintain the "one solid envelope" concept.

I just think that the water absorption test of the ridged polyiso foam board will show that it is not a vital step, but simply one more good option one could chose to use.
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bethiebugs (12-21-2017)
#26
You should not use any water absorbant materials for insulation in a van.

So then there is no such problem.

But that is not what the VP is for in this case, that's just the name for the "tight envelope" (sealed bubble) concept, a leftover from building construction.

My point was just that gaps between layers are not the problem, as long as gaps in the direction between inside and out are minimized, try to stop infiltration, convection, migration.
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#27
I think I need the preschool version of all of this. I am so very confused and overwhelmed with this.
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#28
Stick polyiso up against the sheet body panels, use spray foam to seal around the edges, you want a continuous "envelope" of foam without gaps.

Build your shelving/cabinets whatever will need to hang from the steel posts/beams, so you can put in the necessary supports.

Remove them, then finish insulation, making sure no steel exposed to the interior.

Optional: 6mil plastic sheeting for another continuous 'envelope' aka vapor barrier.

Put the cabinetry supports back in place along with your inner lining to make it look nice.
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bethiebugs (12-22-2017)
#29
(12-22-2017, 11:47 AM)bethiebugs Wrote: I am so very confused and overwhelmed with this.

I am sorry to hear that you still feel that way. Sounds a little to me that it is somewhat similar to how  you  felt in the beginning. 

Is there anything in particular that you have questions about? 
Any of the answers that are particularly confusing to you? 


Try to remember that there is not a commonly agreed upon way, of how to do insulation in a van.  So there is not yet a commonly agreed upon way do-this step-by-step way to follow. 



I have mainly tried to present the idea of a very thick envelope, and how to make every component used to build such a thick envelope (or barrier) maintain its water proof characteristic. Namely, how to extend the thickness of the envelope of the outer metal in the van. 



My main thinking has been, that it is of value, to understand concepts of temperature insulation and concepts of limiting moisture into the materials used to do the temperature insulation. 

And I think it is of value to try to understand advantages and disadvantages of each of the materials that are being used. 

Because once one have a good idea about materials and principles, then it becomes easier to deal with or avoid the disadvantages of each material. 


There are two ways to establish temperature insulation.

- One way it to establish a vacuum between the inner and outer layer. This method is however extremely uncommon, and so far has been very costly, and is thus primarily used in space crafts.  

- The other way is to trap or limit the movement of air, between an outer and inner wall.  And this is the common way to do heat insulation. And the way everything that can be bought in the hardware store works.


A few materials can trap air, in small pockets or bubbles.  These materials are basically water proof as well. polyiso is for instance one such material. 


But most materials simply slow down the movement of air. These are woolly or porous materials.
When woolly or porous materials are exposed to water or condensation or even water vapor, then they will allow moisture to seep (or diffuse) into the spaces otherwise reserved for "trapping" or slowing the air movement. 
So the materials themselves may not absorb water (which is true for glass, rock and polymer materials) but water can be absorbed into the woolly or porous part of the resulting structure. 

One way to use these materials is to enclose them in small bubbles them selves, or to separate them from the lived in space, using an envelope or barrier.
So a watertight bubble can be made when sealing or closing a crevasse or beam with tape over any gaps or holes.


This whole story does however tend to become a longer story, rather than a follow-these-steps-list. 

All of the follow-these-steps-lists, will however be based on understanding of materials, principles and processes.


So when you say "a preschool version", I suppose you would like a follow-these-steps-list, and be done with it?


I do however think that you will discover that people disagree about which list is the best list to follow, and/or will also tend to argue about a detail in one of the steps.

And I suppose you will then need to make up your own mind about which list you prefer, and ask about opinions if there are any specific steps where you can change it a little bit, without disrupting the method or principles that is used as a basis when originally making the list.


I am unfortunately not good at giving people lists, as I myself like to understand why, for each step in a list.   Because only then can I make up my own mind about how to do things my way, and how it for instance suits the current size of my wallet.
And only when I understand why,  can I know about what kind of disadvantages my chosen solution includes, and how a maintenance plan (or ventilation plan) might alleviate or compensate for the disadvantages that I have chosen to live with.


Hence my questions:
Is there anything in particular that you have questions about? 
Any of the answers that are particularly confusing to you?
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#30
As a Newbie here, I have a couple of questions on this topic (at the risk of being seen as hijacking the thread):

Is it necessary to attach insulation to the inside skin of the van?  Couldn't we just attach polysio to the ribs, shiny side towards the van skin, leaving a couple inch air space between the polysio and the van skin?  This would seem to negate the necessity of filling in the ribs.  I was thinking of also attaching sound deadening material such as Dynamat or Hushmat directly to the inside skin (for sound deadening purposes, not insulating purposes) .
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bethiebugs (12-26-2017)


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