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Old 11-11-2010, 10:53 PM   #1
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Question Cotton insulation v.s. alternatives

Like other new sprinter owners, I've been doing research trying to find the best method for insulating the van. I know that there is a lot of controversy surrounding the various insulation methods. So far cotton insulation for the walls is looking like the best option, but I have not seen it discussed in any other posts.

Here's what I've found so far:

Spray foam sounds nice for the high R-value, but I have been warned by a van conversion company that spray foam is not an approved insulation material. I was told that spray foam can dent the body work, plug up the weep holes, cause the van to rust and the foam can crack and break down over time. I was also told that if you ever get a dent and need body work, the body shop will hate you. Plus, foam insulation prior to wiring, etc. would make the job difficult if not impossible later.

Foil covered bubble wrap like “Reflectix” sounds nice and easy and it appears that a lot of folks have used it. I come from a building code background and learned years ago that the manufacturers claimed R-values appear to be misleading at best. To verify that I contacted the WA State University (WSU) Energy office to see if there was any substantiating evidence for the R-value claims. The International Code Council (ICC) governs building codes throughout the US and they have a product evaluation service that verifies claims made by manufacturers of various building products and they publish Evaluation Reports for the products that describe the conditions of use.

WSU Energy office sent me a few publications including ICC ESR-1236 for a bubble wrap product (similar to Reflectix). You can view the report here: http://www.icc-es.org/reports/pdf_fi...S/ESR-1236.pdf. Basically it says under section that in order to achieve an R-value of R-6.36 the bubble wrap must be installed in the midpoint of a 2 x 4 framed wall with (2) 1-5/8" deep air spaces on either side.

WSU Energy office also sent me some PDF attachments that I can't transfer to this post, but basically they said the bubble wrap provided MINIMAL insulating value. In the September 2003 issue of "Energy Design Update", it states that John Straube was hired in 2001 by Covertech Fabricating, a manufacturer of foil-faced bubble pack to conduct tests comparing the performance of their product with 1-inch and 2-inch extruded polystyrene in an under-slab application. The article states; "But after Straube and Schumacher began the test and provided preliminary data to Covertech, the manufacturer pulled the plug on the testing.” Covertech's owner, John Starrr, explained: "We stopped the funding when we weren't getting the results that we wanted to get. So we changed our focus". According to Straube, who is also an assistant professor of civil engineering at the University of Waterloo, "All I have so far is data that suggest that it [foil-faced bubble pack] is better than R-1.1 and worse than R-5 (Note: R-5 is what they needed to achieve to comply with code for slab edge insulation, not that the bubble pack insulation got close to that R-value). The article includes a table listing various manufacturers and claimed R-Values. Most R-values (without added polyethylene foam) claimed the insulation value was between R-1.3 - R-2. In addition, in order to achieve the claimed R-value, there needed to be an "air gap". Some of the posts I've seen here show people layering the bubble wrap which does not appear to give an air gap. The article also discussed the cost ineffectiveness of the product.

The WSU Energy office sent me another PDF attachment titled “A Shot Across the Bubble-Pack Bow” from the March 2006 “Energy Update”. The article states; “Don Fugler, a senior researcher at the Canada Housing and Mortgage Corporation, credited the EDU article as the inspiration for his decision to research the performance of foil-faced bubble-pack products under slabs. Like the EDU, Fugler concluded that “foil bubble pack tested was next to useless as sub-slab insulation.” The article also stated that the FTC sent warning letters in 2004 to several bubble-pack manufacturers, yet there apparently hasn’t been any ongoing enforcement by the FTC. (Note: I do realize that the under slab application is different than for use in a van. But it does not appear to me to have much insulating value especially if it does not have a substantial airspace on either side of the bubble wrap).

Giving up on the bubble wrap idea, I called some van conversion companies and they said they use fiberglass insulation in the walls. I spoke with one long time Sprinter salesman who said that fiberglass should NEVER be used since the vehicle vibration will cause the fiberglass to degrade and create an unhealthy fiberglass dust that "you can never get out of the vehicle”. I have also seen several posts here where people voiced concerns about the dust, the potential for insulation settling and transmission of moisture through the fiberglass leading to rust formation. I really hate dealing with fiberglass insulation anyhow, so I don't need much convincing not to use it!

So I started looking for fiberglass alternatives. I found a polyester batt insulation product by Dow that seemed hopeful; it’s called SAFETOUCH. You can read about it at this website: http://www.dowsafetouch.com/. It can be special ordered through stores like Home Depot and Lowe’s. The R-13 is 3.5" thick, 15" wide and 94" long and each bag has 69 sq ft. So what’s the drawback? It is about $60.00 per bag and there is an 18 bag minimum. From my figures (for the 144” high roof van), it should only take a couple of bags (at 69 sq ft each) to insulate the walls and back doors below the windows.

Then I thought about using wool insulation. Hey, it keeps sheep warm, wool clothes keep us warm and it is naturally fire-resistant. However I saw some posts at another forum where people were concerned wool’s ability to hold moisture and the possibility of causing a future rust problem. The use of a natural material like wool is attractive but felt there wasn’t enough information on its use in a metal vehicle, so I moved on to look for another alternative.

Then I called Sportsmobile in Texas and asked what they used to insulate their vans (Interestingly, Sportsmobile in Fresno, CA uses fiberglass!). The salesman said that they used R-13 cotton insulation in the walls and ½” closed cell foam with 5/16” bubble-film below (I believe he said there was also an airspace somewhere in the ceiling assembly). He said that the cotton insulation is lighter in weight than wool (they tried that previously) and easier to work with. Apparently they have used the cotton insulation for some time and have been very happy with it; especially its good sound deadening qualities.

My internet search led me to a cotton insulation product at http://www.bondedlogic.com. Their product is called “Ultra Touch Natural Cotton Batt Insulation”. Their cotton insulation is treated with a boric acid and ammonium sulfate which inhibit mold, mildew, fungus and pests and provides fire-resistance properties. Per the MSDS the composition is “Recycled Fiber Products, Boric, Ammonium Sulfate, Binder fiber” and it “contains no fiberglass, asbestos, or formaldehyde.” It appears that they have also gone through all of the hoops to PROVE the claims of their product. There is an extensive list of “Technical Documents” including an ICC Evaluation Report verifying the insulation values, etc. So far, I am impressed! The website also has a “Distributor Search” where I was able to find two retail outlets near me that will sell me as little as one bag. The R-13 comes in 16” and 24” widths. The R-13 x 16.25” has 84.88 sq. ft/bag and the R-13 x 24.25 has 126.63 sq. ft/bag. In addition, they have an R-8 product which is 2” thick and has about 129 sq. ft./bag. While compressing the insulation slightly (to fit within the depth of the Sprinter ceiling ribs) would slightly reduce the R-value, it seems like installation of the cotton insulation in the ceiling would be much easier and probably cheaper than trying to layer up closed cell foam, foil covered bubble-wrap with the required air space, or what have you. With slight compression, I would hope to get at least R-6 or R-7 in the ceiling. From my research, closed cell flexible foam is only about R-2 per ½” and if you give the bubble wrap an R-1.1 or R-1.3 that would only give you about R 3.1- R-3.3 or better.

I would appreciate some feedback on this subject; especially the use of the cotton insulation in the walls and ceiling.
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Old 11-12-2010, 12:01 AM   #2
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Default Re: Cotton insulation v.s. alternatives

I've used Reflectix both in my home and RVs with excellent success.
I used it in the walls and ceiling of my addition as a vapor barrier.
In the walls it is in direct contact with the fiberglass batts, studs and sheet rock, with zero airspace around it.
The walls feel room temperature to the touch in the middle of Winter or with the sun blazing on the outside of the wall in Summer. (of course that is along with 6" of fiberglass)

I've also used it in my VW Westfalia both in the wall cavities, outside covering the canvas or windows as a sunshade, and sun covers for my coolers.

Someone else asked that since it's a captive bubble, what would happen at altitude? Good question, since my travels here on the east coast have kept me below 2500ft, I don't have any 1st hand info.

Since I'm also looking to insulate my recently aquired Sprinter I'm also interested in what are the latest insulation products available for it.
I'm leaning tward Reflectix again, but I'm very interested in that UltraTouch w/radiant barrier you mentioned.
I've found it is available at The Home Depot's website: http://www.homedepot.com/webapp/wcs/...atalogId=10053 but not in stores.

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Old 11-12-2010, 12:51 AM   #3
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Default Re: Cotton insulation v.s. alternatives

Other than a vacuum, the best insulation is trapped air between the cold and hot sides. Trapped air alone will circulate by convection with the hot air rising on one side and the cold air falling on the other thus transferring heat from hot to cold. All the conventional materials such as fiberglass, wool, foam, etc. simply immobilize the air preventing circulation. If you study their R values you will find that they are all similar per inch thickness; that is, per inch of trapped air. The reflective bubble wrap materials advertise inflated R values as they only achieve them if installed in the middle of the air space to try to reduce air circulation. Generally this is not very effective. Foil faced bubble wrap does, however, have one great attribute in that it reflects radiant heat rays such as from the sun. The bubbles of trapped air themselves are only a fraction of an inch so they do not provide much R value themselves. I believe the best insulation for a Sprinter, especially if used in southern hot areas, is foil faced bubbles or just plain aluminum foil (shiny side towards the sun) against the roof and sides backed up with an inch or so of conventional insulation. I used rigid foam sheets in the big areas against where windows would be and the pink fiberglass stuff for all the odd areas where it has to be stuffed in. I used the pink stuff with the paper vapor barrier as this helps it hold its shape so as not to crumble and fall down.
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Last edited by Diamondsea; 11-12-2010 at 12:55 AM.
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Old 11-12-2010, 01:36 PM   #4
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Default Re: Cotton insulation v.s. alternatives

Kat, thanks for the good info. I too am preparing to insulate my van and surely want to get it right the first time. Going to check into the cotton route.
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Old 11-12-2010, 06:08 PM   #5
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Default Re: Cotton insulation v.s. alternatives

I went with reflectix ( 2 layers ) and a Dynomat type asphalt based tape. Then the walls are covered with the OEM plastic wall panels provided by MB in the Cargo.
My ceiling will be insulated the same way and then covered with corrugated plastic panels covered in a felt like fabric similar to the headliner above the cockpit.

Cotton collects water !
If you sleep in your conversion, condensation is a major consideration.
Fiberglass is hazardous to your health.
It is actually glass, and breathing those microscopic
particles is cumulative.
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Old 11-12-2010, 09:09 PM   #6
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Default Re: Cotton insulation v.s. alternatives

I have been very happy with my DIY foam job. I'm a whitewater boater and live in the relatively high humidity of the NorthEast. The closed-cell spray foam is fire-rated and totally moisture-proof. I can't tell you how nice it is for the van to resist the musty odor of my previous Econoline. Metal walls of a van do not breathe like the outer envelope of a house---so trapping moisture in the insulation can be a problem in humid climes. Unlikely to be a problem in TX, CA, AZ, NM since the low humidity will suck out any trapped moisture.

The foam tools very readily. I broke a wire to the license plate and it took just moments to dig a channel with the nearest screwdriver. Easy to refill any hole. Very nice to fill the small cavities with the expanding foam. Perhaps the tiniest effort to avoid overfilling a cavity. Stickiest substance I've ever used. It looked like a Buster Keaton movie as I dripped some on me, on the newspapers covering the floor, and of course I walked all over that flypaper. I did use some inexpensive plastic wire chases from HD to keep my electricals separated from the foam. (You have to derate the wire gauge a bit if no air space.)

My advice is to start with a thin layer of specialized acoustic-dampening foam around the wheel wells and wherever else the budget allows. Then foam away with Great Stuff. I glued in rough-cut isocyanurate sections between the roof rafters by buttering them with Great Stuff foam and filling the edges in with it.

I would not use cotton if you spend time in wet climes.

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Old 11-12-2010, 09:35 PM   #7
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Default Re: Cotton insulation v.s. alternatives

Is boric acid corrosive?

I wouldn't be too quick to flush reflectix. I've lived in my van with and without any insulation. Reflectix alone can make a big difference as long as you take into consideration that its purpose is to protect against radiant energy.

I made a window curtain from a product called Warm Window. It is reflective mylar (like space blanket material) sandwiched between polyester quilt batting. I covered the warm window "quilt" with ironing board fabric. The addition of these heavy window covers allows me to sleep a couple extra hours before summer heat drives me out of bed. http://www.warmcompany.com/wwpage.html

Best results will probably come from a combination of materials. My next insulation job will probably involve something like a 1 inch, foil faced foam board. Spray foam for voids and a layer of reflectix. The cotton would probably work well in combination with other materials too. I would be leary of the boric acid unless there was a way to assure me that it could be sealed from any inside or outside moisture.

As for any of these materials not meeting "code", I wouldn't worry about it too much, unless you have a specific aversion to a specific material, like urethane, or you don't like the chronic itch from a constant dusting from fiberglass or.....

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Old 11-12-2010, 10:27 PM   #8
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Default Re: Cotton insulation v.s. alternatives

I know a lot of folks are using the foil bubble wrap but it seems to me that you need to figure out a way to provide an air space between the layer(s) for it to be effective.

Moisture transmission through any type of batt insulation that could condense on the inside of the van body is my only concern. I've read posts here where some people voiced concerns about this issue with fiberglass insulation as well.

Because the UltraTouch is treated with boric acid to prevent mold, I'm not particularly concerned about mold issues. Under FAQ at the Ultra Touch website: http://www.bondedlogic.com/ultratouch-cotton.htm it says:

"Does UltraTouch have a vapor barrier?
No, UltraTouch is manufactured in batt form and is unfaced. If your local building code requires the use of a vapor barrier, we recommend a poly sheeting to be applied across the insulated surface."

Depending on how much money you want to spend, I suppose you could put the foil bubble wrap or one of the self adhering, foil covered, sound deadening products on the metal van interior to help prevent condensation and rust. Then you could install your batt insulation with a vapor barrier on the inside.

The things that are attractive to me about using the cotton insulation are that it is "green"/recycled, it is safe (no itch, no dangerous fibers to breathe, is fire-resistant) and according to the manufacturer (and Sportsmobile, TX) it provides excellent sound-absorbing qualities. If you look at the manufacturers "Performance Brochure" you can read about its physical, thermal and acoustical performance qualities (which have all been verified by independent testing). Under "Physical Properties" it states that it passed ASTM C-739 for moisture absorption (passed-less than 15%). Here is a link to the brochure: http://www.bondedlogic.com/documents...ouch_broch.pdf

So I'm thinking that if ANY type of batt insulation is used, it would be essential to use a vapor barrier (which is rated for 1.0 perm or less dry cup rating) to prevent transmission of moisture from moving from the inside of the van into the batt insulation material and then condensing on the metal body. A minimum 4 mil plastic sheeting material would meet this requirement. However, it would be important to cover the plastic with an interior finish material to meet flame/smoke spread and thermal barrier ratings (i.e. thin plywood or similar). I know that there is a white, plastic type, fiber reinforced material that is used in insulated, unfinished basements that meets all of the smoke, flame spread & thermal barrier requirements. I'm sure this could be purchased from any professional insulation company.

Prior to doing any investigation on insulation materials, my initial thought for insulating the van was to get some pole building/metal building insulation material. It comes in wider widths than typical batt insulation and it has a white plastic type of facing that acts as a vapor barrier and meets the fire safety requirements. In pole/metal buildings, the vapor barrier also acts as the interior wall finish so it is a fairly durable material that also has excellent light reflective properties. Assuming you come up with a way to hold it in place, in theory, you could at least temporarily use it as your van's interior wall finish. Also I assume it is readily available and you could get a small quantity from a metal building/pole building contractor.

Other than the fiberglass dust/air quality issue (which I am concerned about), the only other drawback I can see with it is that you would still need to insulate between the van's metal ribs. So depending on the width of the insulation, you would probably need to hand stuff insulation in the ribs and possibly cut the insulation (leaving vapor barrier uncut) to fit over the ribs without compression. Because pole/metal buildings use metal roofing and siding, it is necessary to have an appropriate insulation material with a vapor barrier to prevent condensation from forming...especially on the metal roofing. This type of insulation has been thoroughly tested and approved for use in metal buildings and has a track record for performance. You can check it out here: http://www.naima.org/pages/products/mb.html

Where I live, houses have to be sealed for air infiltration and they also require vapor barriers on the interior. So they are considered "unusually tight construction". Because of this, the houses are not getting natural air infiltration like older homes or those that aren't required to be sealed tightly. The lack of natural air infiltration creates an indoor air quality problem. Therefore, our state has a ventilation code that requires mechanical ventilation of the structure. With a van that is insulated and has a vapor barrier, you would have the same lack of air infiltration and air quality issues. So you would need to have an inlet for fresh air (screened window?) and some way of exhausting stale air out (Fantastic fan?) if you were going to be sleeping in it.

Anyhow, to reiterate; I think that the use of any form of batt insulation would require a vapor barrier (1 perm or less) on the interior to prevent moisture transmission into the wall cavity that could cause condensation on the vans metal body. And with the addition of insulation and a vapor barrier, there must be a method to introduce fresh air and exhaust stale air in order to maintain healthy air quality.

Appreciate feedback on these issues :)
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Old 11-12-2010, 10:49 PM   #9
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Default Re: Cotton insulation v.s. alternatives

In my old GMC van, I used 1" closed cell polyethylene sheets scavenged from discarded packing material between the ribs, then covered that with with Reflectix. (actually TekFoil from FarmTek.com)
Then I covered the walls and ceiling with a carpet wall covering, screwed to the ribs to keep condensation at bay.
It was very quiet and it could easily be kept a comfortable temperature to camp in.

I've been hoarding 4'x2'x1" sheets leftover from equipment installs again, but since I now have a long tall Sprinter, it might be awhile before I have enough material.

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Old 11-13-2010, 12:14 AM   #10
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Default Re: Cotton insulation v.s. alternatives

My approach to the condensation problem is to eliminate as much air as possible in the wall/ceiling and use closed cell foam. The first thing I am doing is applying "rattletrap" noise reduction material to all the steel surfaces I can reach. I fiqure if metal surface is not in contact with moisture laden air then the mositure will not condense on the steel. By eliminating air in the space, the moisture content of the air is also eliminated. I filled all the corrugations under the wood floor with closed cell foam and will do the same with the roof corrugations. So foil backed rattletrap against the steel, then closed cell foam board and last a layer of reflextix. Where I can not fit closed cell foam, I will use Great Stuff canned foam. 1/4" plywood pop rivited to the wall will cover the insulation.
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