3M Thinsulate Thermal and Acoustical Insulation

mofo989

Member
Please, for the love of God, no more Spray Foam in this thread. ;) I get it, Spray Foam has advantages. I don't want to use it. Let's talk about Thinsulate here.
 

mofo989

Member
I received my 3M MA6720 Thinsulate. Here is my plan for install. Comments welcome (except for recommending use of spray foam.. hah hah).

(steel vehicle skin)
-- THINSULATE 2"--
-- THINSTLATE (additional 2") --
-- REFLECTIX --
(interior)

I decided to follow this layering and put the reflectix vapor "retarder" toward the interior for a few reasons:

* Reflectix and other radiant insulation suggests an air gap on the exterior side to provide any R-value benefit. This will also avoid conduction of heat from the metal to the reflectix metallic foil, and also will prevent any galvanic corrosion should the metal be incompatible (although the paint might be enough to protect from corrosion).
* The thinsulate is hydrophobic so it will be less likely to degrade with condensation (this is approved for marine use).
* The voids in the sprinter will not be air-tight, no matter how hard I try. There appear to be drain holes in the wall voids where they meet the floor as well, which may help expel condensed drops.
* It is true, air trapped within the void during installation will have moisture in it, but this is not different than house construction where the air is trapped in the wood wall voids between sheetrock and vapor barrier. Maybe the trapped moisture can diffuse to the exterior in a house, but drywall also allows some moisture diffusion back in. So we assume some amount of moisture by diffusion is tolerable and will not cause damage. I have to assume the auto manufacturers have planned for some moisture to condense at times as well. Most cars fog up at times and they dont tuen to rust buckets.

I plan to adhere the thinsulate to the metal wall with squares of 3M Fastener TB3571/TB3572 Hook/Loop (ie velcro). The glue of the velcro is more important than the velcro itself, and 3M's selector guide indicates this part will hold up to 200 degrees F, which is pretty good (I have white paint by the way)

I plan to adhere the thinsulate layers (as applicable depending on void depth) to each other using 3M 76 Hi-Tack Spray Adhesive. I selected this spray adhesive because its datasheet says it is "an excellent choice for fabric headliners" and is good for 230 degrees F; specifically marketed for "fabric in van conversions" and to "bond insulation in aircraft interiors" here.

I'll use reflectix tape to attach relfectix to the ribs of the vehicle, covering each void.
 

hkpierce

'02 140 Hi BlueBlk Pass
I plan to adhere the thinsulate to the metal wall with squares of 3M Fastener TB3571/TB3572 Hook/Loop (ie velcro). The glue of the velcro is more important than the velcro itself, and 3M's selector guide indicates this part will hold up to 200 degrees F, which is pretty good (I have white paint by the way)

I plan to adhere the thinsulate layers (as applicable depending on void depth) to each other using 3M 76 Hi-Tack Spray Adhesive. I selected this spray adhesive because its datasheet says it is "an excellent choice for fabric headliners" and is good for 230 degrees F; specifically marketed for "fabric in van conversions" and to "bond insulation in aircraft interiors" here.
Just as a data point, I measured in the 160s F for the exterior of my blue-black van:
https://sprinter-source.com/forums/showpost.php?p=61886&postcount=17
https://sprinter-source.com/forums/showpost.php?p=61886&postcount=21
 

tDot

Active member
I received my 3M MA6720 Thinsulate. Here is my plan for install. Comments welcome (except for recommending use of spray foam.. hah hah).

(steel vehicle skin)
-- THINSULATE 2"--
-- THINSTLATE (additional 2") --
-- REFLECTIX --
(interior)

Where did you buy the MA6720 from? I'm still very interested in using this product, but haven't been able to find a supplier that will sell less then a full roll.

Just a note on your layout of insulation and vapour barrier (reflectix). Condensation will likely occur between the steel skin of the van and the back of the reflectix. This condensation will have no way of drying out, and will stay in the Thinsulate insulation unless you make allowances for this type of system to breath..... right now you're essentially put a mass of air between two impermeable materials... unless you were to seal that wall void while working in a vacuum, there will be some volume of moisture in the air that is present in that space, and once the dew point of the ambient air hits the same temp of the air that is in that thinsulate insulation, you will have condensation in an area that you thought was dry.

Of course if you live in Arizona, this is less of a problem then if you live in Seattle.
 

mofo989

Member
Where did you buy the MA6720 from?
Check eBay, it's there!

I think your concern about the trapped moisture is technically real, but is it a problem? It won't be 100% sealed, no matter how hard I try. The Reflectix has a "Water Vapor Transmission (ASTM E 96): 0.02", which is small but non-zero.

Here's something I am wondering about: Vents in D-pillar, where are they and what do they look like?

MB says "Model 906.6/7 the fresh air escapes from the vehicle through the two vent flaps integrated into the left rear D-pillar. "

I want to be sure I don't seal these up!

Edit: looks like P/N A9066920822 is this vent. I'll have to look for it!
 
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mofo989

Member
Thanks. This validates my concern of using high-temp adhesives in this case.

I am tempted to glue everything to the reflectix instead of using the velcro, it will keep the adhesive off of the exterior skin high temps. This will make single removable assemblies if I pull the tape off. Also it will hold the thinsulate off of/away from the sheet metal which is the condensing surface, this less introduction of misture into the insulation. I think this is how the automotive OEMs use it, attaching to interior panels, not vehicle skin.
 

mofo989

Member
Hmm.. the more I think about this the less I like the idea of a VAPOR barrier at all. Read this. Maybe what we need is a vapor-breathable AIR-barrier! That is, we don't want drafts and air currents that carry our moist air out of the van to touch the cold metal skin as it passes by. We DO want moisture against this skin to evaporate and diffuse as necessary without being trapped. Even with reflectix against the metal skin directly you run the risk of air pockets and tape failures (I wonder how well the adhesive of reflectix tape holds up under temp!) where moisture can collect.

Tyvec house wrap has HIGH vapor permeability, ASTM E96 of 400 g/m^2 in 24hrs. Reflectix is LOW .02 perms = .013 g/m^2 in 24hrs.

This is a big difference. Have we been thinking the need for a vapor barrier incorrectly or am I off here?
 
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tDot

Active member
Hmm.. the more I think about this the less I like the idea of a VAPOR barrier at all. Read this. Maybe what we need is a vapor-breathable AIR-barrier! That is, we don't want drafts and air currents that carry our moist air out of the van to touch the cold metal skin as it passes by. We DO want moisture against this skin to evaporate and diffuse as necessary without being trapped. Even with reflectix against the metal skin directly you run the risk of air pockets and tape failures (I wonder how well the adhesive of reflectix tape holds up under temp!) where moisture can collect.

Tyvec house wrap has HIGH vapor permeability, ASTM E96 of 400 g/m^2 in 24hrs. Reflectix is LOW .02 perms = .013 g/m^2 in 24hrs.

This is a big difference. Have we been thinking the need for a vapor barrier incorrectly or am I off here?
I don't think you are off, there may be some who disagree with me, but I dont agree with people putting true vapour barriers on the inside of their vans.

But, all of my theory comes from home building.

The nice thing about an air barrier is that it prevents excess moisture from cooking, bodies, etc. from passing through and into the moisture. It acts more like Gore Tex instead of a rubber rain jacket.

I personally prefer Typar over Tyvek, it's perm ratings used to be substantially better, but its been a few years since I've read the specs.

Now the trick is to allow the surface of the air barrier to vent. Air imperiable substrates, such as plywood (the glue layers) and rubber or plastic sheet goods, would also act as a vapour barrier.
 

tDot

Active member
I'm now leaning towards a hybrid system of 1/2" of closed cell spray foam on the van skin, and the MA6720 on the inside of the vehicle.

I also want the sound insulation of the thinsulate. Closed cell spray in foam is an amazing transmitter of noise. Open cell spray foam will not transmit as much noise, but it has a much lower r-value and it could allow vapour to migrate to the skin of the van and be trapped there in its liquid form.

R=Value on spray foam is a funny thing.... it's basically useless, as all of the tests are based around the idea of how batt insulation works.

I've sprayed closed cell insulation onto concrete walls in basements, at around 1/2" thick, this alone should only be about R3.5 (iirc). The net result was far superior to R14 batt insulation and a sealed vapour barrier. Combine the two systems and in my opinion it starts to feel more like a room with R28 insulation. There are some pretty advance hybrid insulation practices being developed currently, it'll be interesting to see where we are at in 10 years.
 

mofo989

Member
I think your idea of a hybrid solution is a good one, and I agree with others that the spray foam solves the issues of any possible air gap where condensation can form. That said, I don't like the lack of reversibility of that installation. I like to be able to easily undo what I do to the van, when reasonable.
 

OrioN

2008 2500 170" EXT
I think your idea of a hybrid solution is a good one, and I agree with others that the spray foam solves the issues of any possible air gap where condensation can form. That said, I don't like the lack of reversibility of that installation. I like to be able to easily undo what I do to the van, when reasonable.
...describe/explain a reason or scenario where you would need to undo a sprayfoam application...
 

mofo989

Member
Started the insulation effort. I'm about 2/3 done with the project and I have used 125 sq ft. Roof and everything above the windows is done. So far the van seems noticeably quieter. Can't hear the rain drops on the sheet metal nearly as well and my test drive yields good subjective results. Headliners still out so it should only get better.

The Thinsulate is very easy to work with. The MSDS indicates no health hazards, and there is no itch and just a little bit of white dust after cutting. Can cut with scissors, but also used a a rotary quilting cutter to get cleaner cuts. It will tear if you are too rough with it. One side scrim is a lot more fragile, the other side is a bit thicker scrim. The 3M velcro only adheres well to the thicker scrim, it just pulls off too easily if stuck to the thiner side. You do have to be a bit gentle with it if you use velcro since the Thinsulate will tear before the the velcro will release unless you hold hold the scrim as you pull. I used small squares of velcro for the ceiling panels. The material lofts quite a bit after you start working with it, about 2". I am finding that in the upper bays and ceiling only need one layer of the stuff. Below the windows it can support double layers.
 
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GeorgeRa

2013 Sprinter DIY 144WB, Portland OR
Started the insulation effort. I'm about 2/3 done with the project and I have used 125 sq ft. Roof and everything above the windows is done. So far the van seems noticeably quieter. Can't hear the rain drops on the sheet metal nearly as well and my test drive yields good subjective results. Headliners still out so it should only get better.

The Thinsulate is very easy to work with. The MSDS indicates no health hazards, and there is no itch and just a little bit of white dust after cutting. Can cut with scissors, but also used a a rotary quilting cutter to get cleaner cuts. It will tear if you are too rough with it. One side scrim is a lot more fragile, the other side is a bit thicker scrim. The 3M velcro only adheres well to the thicker scrim, it just pulls off too easily if stuck to the thiner side. You do have to be a bit gentle with it if you use velcro since the Thinsulate will tear before the the velcro will release unless you hold hold the scrim as you pull. I used small squares of velcro for the ceiling panels. The material lofts quite a bit after you start working with it, about 2". I am finding that in the upper bays and ceiling only need one layer of the stuff. Below the windows it can support double layers.
It would be nice to see some pictures. Do you have a passenger van?

George.

http://www.youtube.com/watch?v=dq671waCndc
 
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mofo989

Member
Thanks for the video, the insulation looks just like that. I have a passenger van. I decided to go ahead and use the Tyvek ThermaWrap as my air-barrier. I am special ordering if from Home Depot (BWTYVTW150 Tyvek ThermaWrap 5' x 150'). the product has a metalized coating, but is also vapor permeable. It's not as low of an emissivity as reflectix, but I figured the benefits of the vapor permeability in a single product made it worth the tradeoff. I will have a lot extra if anyone is interesting in buying some.
 

mofo989

Member
Attached is a photo of the result. I ended up using about 190 sq ft to do the whole van with double layers in lower sections. The driver/passenger doors are not done to my satisfaction since putting Thinsulate inside the door cavity would be not a good application due to more constant moisture and potential window motor interference. I plan to put Dynamat Xtreme inside the doors, and the Thinsulate will go between the water barrier and plastic door trim.
 

Attachments

d_bertko

New member
Looking quite cozy with that complete coverage of the sheet metal.

If that is a window van that you have you could consider making some window inserts out of any leftover Thinsulate. Pretty ideal material for something easy to store when not needed. Figure you'd use them on the coldest nights/hottest days when visibility was not an issue.

The R-1 windows might be as much as 10x as lossy as your walls and ceiling. That could amount to half the btus gained and lost on a fully windowed van.

One does not need thermal perfection. I have some fancy mylarized quilted fabric for my window insert to-do list. With only three cargo area windows the Airtronic d2 does not struggle to heat my van on single-digit F camping nights without inserts. So the extra fuss for yours might not be worthwhile even with more window area than mine.

Dan
 

atulin

New member

mofo989

Member
If that is a window van that you have you could consider making some window inserts out of any leftover Thinsulate. Pretty ideal material for something easy to store when not needed. Figure you'd use them on the coldest nights/hottest days when visibility was not an issue.
I think the Thinsulate is a bit too fragile to be handled frequently. I do plan cut window shades for all the windows using reflectix, and mount them with 3M dual-lock.
 
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d_bertko

New member
I think the Thinsulate is a bit too fragile to be handled frequently. I do plan cut window shades for all the windows using reflectix, and mount them with 3M dual-lock.
I had in mind that you'd sandwich the Thinsulate between some mylar and curtain fabric.

The maximum-hold dual-lock I used on my whitewater boat does the job. Likely too well for a similar curtain use. Perhaps the less grippy version of it would be better than less sq inches on a curtain application.

Attaching curtains can be interesting since you'd like privacy and ventilation in temperate weather.
 

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