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Discussion Starter #1
What is the driving reason for people to fill those small spaces, rather than place a thermal break between those beams / columns and the van interior, and be done with it? :s

I don't understand what advantage there would be in filling those small cavities when the metal surrounding them will conduct heat from inside to outside (and vice versa), right around the insulation someone might bother to fill them with. There appears to be no reward to justify the effort.

Compare, for argument's sake, to the clearly advantageous method of covering a flat panel so the insulation separates the metal heat-conducting panel from the interior air.

Stuffing those metal boxes provides no barrier to the thermal bridge those structures create between outside and inside temperatures through the metal itself. It is certainly a way to keep whatever insulation you put in there warm, but what good is that?

This filling method on small spaces surrounded by metal seems much ado about nothing. If there is a reason based upon thermodynamics for doing so I'd be interested in learning what it might be.
 

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What is the driving reason for people to fill those small spaces, rather than place a thermal break between those beams / columns and the van interior, and be done with it? :s
Noise; which sneaks in through small passages especially down low. Thermally, a thoroughly insulated van is going to perform better than one with incomplete insulation.

It's not a brain friendly, easy to visualize & solve, one-size-fits-all-areas analysis. The thermal/acoustical model and behavior is much more complex. The whole thing acts as a system and we have found that being thorough works very well. The incremental cost in material and effort is small.

Happy Thanksgiving!
Hein
 

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there's a sucker born every minute!

but this is partly understandable: most people want an east/west bed so they have room for a full camper build, but then they have to compromise on the insulation to try to make it all fit. so they stuff insulation in every nook and cranny not being used and hope it will be good enough.

i know this all too well myself with my no exposed steel, well insulated van with a north/south full queen sized bed, (60x80) the bed takes up 2/3 of the van! but i have managed to shoehorn a good sized refrigerator, a microwave and a heater into it, with a portable toilet and a portable propane stove/oven under the bed.

on the plus side: the cab (front) AC does a great job of cooling the entire van on the hottest of summer days!
 

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Discussion Starter #5 (Edited)
Noise; which sneaks in through small passages especially down low. Thermally, a thoroughly insulated van is going to perform better than one with incomplete insulation.

It's not a brain friendly, easy to visualize & solve, one-size-fits-all-areas analysis. The thermal/acoustical model and behavior is much more complex. The whole thing acts as a system and we have found that being thorough works very well. The incremental cost in material and effort is small.

Happy Thanksgiving!
Hein
Thanks for the reply.

I'm very happy after measuring an 8db-10db reduction in noise at various speeds on the same road after covering the large panels with one or two layers of Thinsulate CS150 along with Polyiso placed to isolate both the large panels and those structural channels on the walls from the interior space. (Polyiso isn't rated as well of an acoustic damper as Thinsulate)

This was achieved without having filled any of those channel spaces, only covering them. The before and after db numbers are in the Vanderloosed build thread. This reduction in noise was achieved without having installed insulation inside the doors, on the slider window cutout panel, rear window cutout panels, or over the cab. Though each of those large areas will be done eventually. This effect was easily measurable using the Android sound app specified in that thread.

My experience in applying this method was a significant improvement in comfort acoustically. It emphasized how placing the insulation between the source and the interior achieved remarkable results.

Placing more Thinsulate in the inner door panels, slider window panel, and cab overhead will bring that number down further, though I wouldn't expect these steps to be as significant as what has been achieved so far. I've likely reached a point of diminishing returns after addressing the most significant sources of thermal and acoustic transfer.

As with the thermal aspect outlined, based on surface area covered and these measurements, this indicates there may be very little advantage acoustically to filling those spaces. How much greater overall db reduction could be expected by doing so?

I would be interested to see measured results before and after filling the small voids to support such claims of benefit. Putting a layer of Thinsulate over the inner-facing side of the channels will likely provide better results in preventing sound resonance carried into the van through the metal of those channels than would filling the void. Same as it will with preventing thermal bridging in a way that filling those voids does not address.

With the goal being to block the thermal and acoustic transfer between the outside and the inside of the van, the channel itself offers a highly conductive path for both forms of energy around any insulation placed inside it. This path is the one that will need to be blocked, and placing insulation inside the channel will have but a tiny effect, if any at all, when compared to the effect of placing a layer between the channel and the van interior. At a guess I'd venture it provides less than a 1% improvement inside the channel, and significantly greater damping can be achieved by covering the channel side facing the van interior.

I'd be interested to read more about this complex behavior of the thermal/acoustic model, specifically in regard to any advantage gained by placing insulation inside small enclosed spaces attached to larger thermal/acoustic conductors, as opposed to placing a layer between the acoustic/thermal conductor and the area to be isolated.

Thanks for any more specific detail that might shed light on perceived benefits of this method and measurement of its actual effect regarding overall thermal/acoustic damping for a van application.

Best wishes for a wonderful holiday!
 

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Stuffing the channels won't do anything for thermal performance. This is easily proven by algebraic thermal loss calculations - no need for quantitative measurement. If maximizing space is an issue, 1/4" compression-resistant thermal strip may help. I like the look of HardieBreak http://www.jameshardie.com.au/products/thermal-break/hardiebreak-thermal-strip/
"available nationwide"...in Australia :rolleyes: . Maybe there's an analog for N. America.

OTOH, stuffing the channels will reduce sound resonance and conductance. But the extent is not easily calculated, acoustics being largely the realm of unresolved partial differential equations and voodoo. I doubt anyone here is going to test the hypothesis on two otherwise identical vans. In the overall picture of a project van, it seems worth the relatively small increment of cost and effort...if one keeps a healthy perspective regarding perfection :p .
http://www.jameshardie.com.au/products/thermal-break/hardiebreak-thermal-strip/
 

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Discussion Starter #7 (Edited)
OTOH, stuffing the channels will reduce sound resonance and conductance. But the extent is not easily calculated, acoustics being largely the realm of unresolved partial differential equations and voodoo. I doubt anyone here is going to test the hypothesis on two otherwise identical vans. In the overall picture of a project van, it seems worth the relatively small increment of cost and effort...if one keeps a healthy perspective regarding perfection :p .
Your feedback is much appreciated.

As for empirical testing I was hoping someone might perform such measurements on one van. Before and after. No need for two identical vans. My guess is there would be no discernible difference in sound damping, regardless of whether the other surfaces had, or had not yet been covered before stuffing the channels. So long as everything else is the same for both test samples it should provide validation of whether or not such effort yields any result which could be noticed at all.

Whatever the cost in time and money, if it actually makes no difference this leads back to the question this thread raises, "Why?" and the answer seems to be more about voodoo and the pursuit of infinitesimally small increments toward perfection which may not ever be successfully achieved. Some people have time for that kind of malarkey, and I suppose also will have appreciation for whatever peace of mind such a placebo might bring. Which is fine, as most decisions along these lines will be based as much in emotion as they will be in any actual result. We should all strive to be happy.:D

Its one thing for an Audiophile to craft a home theater room and another for the same audiophile to try to achieve the same level of audio quality in a vehicle. That's a fool's errand as the vast number of other variables encountered in a vehicle installation will make it quite impractical to aim so high. This level of "insulation" falls into that category. There are too many other things, like windows, which will undermine any minute benefit stuffing the channels might provide. Presuming that the builder in their quest for perfection then also covers the interior metal with a thermal/acoustic insulator like CS150, Yoga mat, or Polyiso. Without which stuffing the channel is moot in regard to thermal and acoustic damping.

Perception is always a personal affair. Believing something is "better" makes us feel good, regardless of the fact that we can't actually tell whether it is, or isn't.

My healthy perspective regarding perfection was the impetus behind this thread. ;) If there is no significant advantage, whatever effort expended could be better spent on completing some other more worthwhile aspect of a build. For me, part of "being thorough" is being able to tell when being too thorough is not much different than being wasteful.
 

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this man has done a good job of documenting the many types of insulation, although his thinsulate links now appear to be broken when in the recent past they worked.

also he sometimes comments on this (transit) forum.

http://www.buildagreenrv.com/design-and-build-information-for-camper-vans/install-insulation/
Hi,
I fixed up the link for Thinsulate R value and added another from 3M for the SM600 material that a lot of people are using -- looks like about R3 per inch.

I'm not so sure that insulating the small cavities inside the box frames is not worthwhile from a thermal insulation point of view.
Its not like the box frame metal elements have an R value of zero -- the metal itself is near zero R value, but the still air layer that surrounds the metal has an R value of about 0.7. and there is also an air layer outside the van with an R value of about 0.3 to 0.7 depending on how still the air is. This is basically just like a window -- the glass has a near zero R value, but the air layers on each side of the glass pane result in a single pane window having an R value of about 1.0. So, the area you insulate inside the box frame goes from an R value of about 1 for the van skin airlayers to about R6 (depending on what kind of insulation you use. And, the heat loss from the frame webs that run perpendicular to the van skin is greatly reduced because it faces the insulation you put in the cavity rather than air. If you can get some insulation over the inside flanges of the box beams, than the box frame heat loss though the frames would be greatly reduced.

It would take a careful analysis with one of the 3D flow heat loss tools to really determine what the payoff for insulating the box frame spaces, but I'm inclined to think its not tiny. Maybe filling them up with Great Stuff would be easier than pulling Thinsulate into them?

Gary
 

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Hi,

Maybe filling them up with Great Stuff would be easier than pulling Thinsulate into them?

Gary
No. The Great Stuff may lift the plastic plugs that Ford installs at the rib locations. I can assure you that the water leak created can be substantial. Been there done that!
 

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Hi,
Maybe filling them up with Great Stuff would be easier than pulling Thinsulate into them?
Gary
I agree with Dave. Don't do this. The Greatstuff won't cure in an enclosed space (needs moisture) and then it will later ooze out when skin temps increase. It can also cause ripples in the body where it pushes the skin away but the factory structure keeps other areas from moving. You can then see where the structure attaches to the body skin.
 

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I agree with Dave. Don't do this. The Greatstuff won't cure in an enclosed space (needs moisture) and then it will later ooze out when skin temps increase. It can also cause ripples in the body where it pushes the skin away but the factory structure keeps other areas from moving. You can then see where the structure attaches to the body skin.

Hi Hein,
That has not been my experience -- it may take a little longer to cure, but it does cure.

Gary
 

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Hi Hein,
That has not been my experience -- it may take a little longer to cure, but it does cure.
Gary
It oozed out of the enclosed spaces on our Sprinter for an entire summer everytime it got warm out. It was a persistent mess. And it popped out the plugs on Dave's Transit. The Transit body is very thin so extremely prone to deformation. Maybe you've had better luck on your ProMaster. But if you ever need body repair then the bodyshop will hate you for having the expanded foam in there.

It appears to me that folks who have trouble accepting the fact that pulling and poking Thinsulate into enclosed spaces does indeed make a difference; are the ones who haven't tried. If they had then they would realize how relatively easy it is to accomplish and appreciate the difference it does truly make.
 

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Everyone has an opinion.
I commend Vanderloosed on his sound measurements. Wish I would have done that.
An early step in my conversion was about .5" of spray foam to cover the walls and ceiling. I filled the rest of the space, up to the level of the ribs / internal structure, with Thinsulate. Since it was easy at the time I filled many of the cavities with spray foam. I think this was a mistake.

I think the open cavities and channels are much more devastating to noise and heat than one would expect. For heat, they act like a chimney. As it warms, the air rises in the channel dragging in more air at the bottom. The thermal loss will be much greater than just the R values because of the air movement. Sound does the same thing, being channeled from the noisy floor to ear level. Filling the channel with foam stops both those effects but, for sound, since the foam I used is fairly rigid, it connected the outside skin to the inside of the van. So less noise from the floor but the same or more from the walls and frame. At least that is my assessment. If I would have loose filled the channel (with thinsulate or other material) I would have stopped the air and noise without making a firm connection to the outside wall and bringing in more noise.

I think loose fill of the small cavities is a good idea.

Ron
 

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LOL! Thank you, RonR, for giving me better reasons for filling everything I could stuff polyester batting into, than "because I could" :) Or "because it was kind of fun", or even "so the electric cord wouldn't rattle around"

I used a piece of polyethylene rod used for plastic welding - it was about 3/16" thick, a foot long, firm but flexible. It let me stuff batting into 1/4" holes quite nicely.
 

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Hi,
Agree that it would be really nice to get some actual before and after noise measurements on conversion vans.

I took some in my van and proposed a standard way to do the measurements -- details here: http://www.buildagreenrv.com/our-conversion/our-promaster-camper-van-conversion-measuring-noise-levels/

Its not a very well written page, but if you go down the the heading "Simplified Test" it gives a short description of a proposed standard procedure.
Any noise measurements are helpful, but if we can standardize on noise meter placement, type of highway surface, speed, ... the results will be more useful.

My van is a ProMaster, but I think that noise level reductions for a particular type of treatment would be similar for Transit, Sprinter and ProMaster.

Gary
 

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Regarding conduction/thermal bridging...

Please recall that most van skins are bonded to the structure with reasonably thick beads of (foaming) adhesive. Those materials do act as thermal breaks between skin and interior structure. It's not going to keep the interior metal from getting chilled if your van is parked in the cold with no heat. But the adhesives will reduce conduction once you get it warm inside. Insulating the cavities will only add to the overall thermal efficiency. Certainly not reduce it.

Wood conducts too (although less than metal), but it would be silly to build a house and deliberately leave un-insulated pockets within the walls or roof. I can see similar visual effects (as photo above) of thermal bridging on our home in certain conditions.

The existence of thermal bridging does not mean you shouldn't insulate everywhere else.
 

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I made a mistake when building the sold Sprinter conversion. The 80/20 aluminum cabinet structures were bolted directly to the van steel. Net result was the aluminum structures were close to the van steel temperature. Seems aluminum is a very good conductor. Just bypassed all the wall, floor and ceiling insulation.

In Transit build I isolated the aluminum structures from the van steel. Bolted the plywood floor to the van steel and then bolted the 80/20 to the wood floor to create a thermal break. The upper cabinet frames are hung from the ribs with plywood tabs between the roof rib and the extrusion. The plywood cabinet floor connects the bottom of the 80/20 face frame to the wall.

Where I bolted the structures to the van walls with plusnuts I used a plastic spacer between the connector and the wall and a plastic spacer under the bolt head. Did not want metal to metal contact.

Did bolt the structure to the van wall at one location to ground the structure to the van.
 

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Discussion Starter #20
I made a mistake when building the sold Sprinter conversion. The 80/20 aluminum cabinet structures were bolted directly to the van steel. Net result was the aluminum structures were close to the van steel temperature. Seems aluminum is a very good conductor. Just bypassed all the wall, floor and ceiling insulation.

In Transit build I isolated the aluminum structures from the van steel. Bolted the plywood floor to the van steel and then bolted the 80/20 to the wood floor to create a thermal break. The upper cabinet frames are hung from the ribs with plywood tabs between the roof rib and the extrusion. The plywood cabinet floor connects the bottom of the 80/20 face frame to the wall.

Where I bolted the structures to the van walls with plusnuts I used a plastic spacer between the connector and the wall and a plastic spacer under the bolt head. Did not want metal to metal contact.

Did bolt the structure to the van wall at one location to ground the structure to the van.
This describes best what I was trying to convey regarding how effective the metal that form these boxed channels can be for moving heat. (more so when you attach aluminum heat sinks to the metal van as Orton describes) The metal is exponentially more efficient at moving heat than might be done by passing from one metal side, radiated into the air inside the channel, then onto the other metal side. Any insulation done inside the cavities will have an inconsequential effect overall. Measurable? Sure. Just not of any significant effect overall. The metal is much more efficient at moving heat in or out (as temperature differential dictates) quickly and efficiently. The only effective way to stop this is to isolate that metal from the interior space with an insulation barrier.

Sure, stuffing insulation in the cavity will have "some" effect. Perhaps, only mitigating a few tenths of a percent of the total heat transfer from any given channel when compared to the rate of heat transfer through the metal.

This is what makes the process seem like an exercise in futility to me. I don't believe that the folks supporting this technique have a good working understanding of the minuscule effect their efforts will provide against the capacity of the metal to transfer heat right around whatever they put in there.

Likewise for mitigating noise. Sound needs to be prevented from vibrating the air in the living space that will conduct it to one's ear. That point will always be outside the channel, not inside it.
 
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