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I just found a roll of Tyvek Thermawrap 5.0 marked down at HD for $0.82/sqft (CAD). It resembles 2" Thinsulate bonded to Tyvek. Google says it's hydrophobic polyester. I only found a few vague references in RV forums and none negative. Google also says there was a class-action suit filed by homebuilders (etc) over false (exaggerated) advertising. That doesn't bother me since it wasn't the product's fault. I'm thinking it should be OK to treat it like Thinsulate, i.e., glue the scrim side (Tyvek) to the body metal (or foam board). Anybody know of any downsides?
 

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I'm sure someone will mention FMVSS or why try something new when we know what works.

If its cost effective for you then do it. I don't think there is a downside.

Some tidbits, you can get 20 oz polyester batting (1.5") .30 usd/sqft, Polyiso (1") is .60 usd/sqft, Thermawrap (1.5") 1.30 usd/sqft, thinsulate (1.5") 2.70 usd/sqft. Thermawrap is polyester and polyolefin. If you want to improve fiberous types of insulation they need to be encapsulated like a blanket.
 

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phil makes a good point that has not been brought up as far as I know. Fibrous insulation is MUCH LESS effective if not encapsulated. Its rating requires that convective air currents not be allowed to pass through it. This is hard to do in a van as fibrous insulation in the walls is in a space that exterior or interior heating of the air in the insulation between the walls will force convection towards the ceiling in the sun and towards the floor at night. Preventing this would require an air block at the floor and ceiling. How can that be done? I built energy star rated homes and getting that done with fiberglass insulation requires all six sides and edges of each insulated cavity to be closed off. The infrared exam during the certification testing demonstrates this for the rating inspector.
 

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Hi,
Interesting product.

Looks like its the Tyvek house wrap with a 1.5 inch thick insulating bat material bonded to the Tyvek. The insulating material "looks like fiberglass", but is "a mixture of polyester and polyolefin fibers". It is said to provide R5 as long as its not compressed. R5 is not bad for 1.5 inches -- about the same as Thinsulate.
Pretty good article on using it for house insulation: http://www.greenbuildingadvisor.com/blogs/dept/musings/two-new-exterior-insulation-products-walls.

Looks like its about $1.35 a sqft in rolls that are 4 ft wide by 40 ft long. Fairly inexpensive, but I guess you have to buy it in full rolls.


Its intended use is outside the sheathing on homes where it can cut down on the thermal bridging through the wall studs. The Tyvek is water vapor permeable, so it allows any water that gets into the wall to dry to the outside.

For van insulation, I guess it could be used in the same way as Thinsulate is used.

I guess I still like either rigid polyiso sheets that are glued to the van wall with Great Stuff, or the urethane spray foam insulation. Reason being that both of these are water vapor impermeable, so the don't let water vapor get to the van wall and condense on the cold metal van wall.

Gary
 

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I chose Thermawrap 5.0 --- nabbed 2 rolls (320sqft) for $250 before tax, http://www.dupont.com/products-and-services/construction-materials/building-envelope-systems/brands/water-barrier-systems/products/Thermawrap-r5.html to use in the doors, stuff all the nooks and crannies with, and generally fill voids as I piece together the built-ins... It took a few calls and the supplies outfit must've liked me as they sold it at jobber price not retail.

I've looked at the fire/smoke ratings - biggest danger with both PE/PET fiber products is exposure to temperatures that melt the plastics to run/drip/pool as then will there be enough fuel in one place to really burn, otherwise it tends to melt back away from heat source before it ignites, part of why they can brag on the fire hazard indexes the way they are tested.

The stuff is difficult to cut, it's not fabric. Hard straight edge to compress the fibers and carpet cutter or circular razor, note scissor style tools will wear you out rapidly, tough strings of the stuff slips by the cutting edge trying to use really heavy snips - this circular cutter http://www.ebay.com/sch/?_from=R40&_nkw=Olfa+Deluxe+Rotary+Cutter-60mm is on their recommended list.

On my window van I used iso foam, foil covered on both sides, 3M 90 and low expansion spray foam. We placed a 1/2" layer above/below windows and then added an extra 1" layer below the window areas and grouted the panels flush with spray foam between layers. So, Thermawrap will get laminated over the foam as filler. I've also got a 27' Airstream trailer project, anything left over will be filler in the shell cavities there.

The wrap I've used so far I peeled off the Tyvek to use it, above the cab ceiling liner and the whole cabs roof line on a high roof van, and narrow strips in the beams that didn't get filled with spray foam. On as many sections as I can we will use the tyvek side towards the interior and seal edges with one of the forever all-weather sheathing tape, compartmentalize & baffle air leaks using the tyvek sheet. The TW has an R-Value of 1.5 even when compressed to 1/4" which is pretty impressive as many 5mm reflective foams are R-0.7 without the foil trickery.

Anyhow for my project, R-3 to R9 of polyiso foam, adhesives and one/two layers of Thermowrap for R13+ depending, I'm still less money per square foot than a single layer of that highly merchandised similar product.

FAQ's here: http://tinyurl.com/kcnh7t3
 

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The stuff is difficult to cut, it's not fabric. Hard straight edge to compress the fibers and carpet cutter or circular razor, note scissor style tools will wear you out rapidly, tough strings of the stuff slips by the cutting edge trying to use really heavy snips - this circular cutter http://www.ebay.com/sch/?_from=R40&_nkw=Olfa+Deluxe+Rotary+Cutter-60mm is on their recommended list.
Thanks, Zoomyn. Please continue to share your insulation experience as it unfolds. I'm only a month away from all this myself.
 

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Remember there is usually a trade price and a retail price, the company account price vs. walk-in price. Looking up the receipt I paid $128.99/Roll in June 2015 for $280 total w/ taxes.

I went through Duponts stocking dealer list and called around, many listings were no longer in business, found a local previously unknown hidden lumber yard tucked between a rail spur and nearly a mile of huge grain silos not too far away... coincidentally spoke with one of the owners who was quizzed me over the application - of course I lied and spoke only of a false bulkhead covering prior work, it would be at roof height and I had to assure the gentleman no moisture could get behind it.

They had the product Spee-Dee Delivery overnight delivered and available 24 hours after I called, and all of their three employees turned out when I came to pick it up and they got the full story, were either very interested in the Promaster or enjoyed watching me squirm as they quizzed me.. The fellow I'd spoken on the phone with did not seem disappointed in that I was not a licensed contractor but saw I was as poor as a church mouse as I payed cash and just smiled away as I loaded it and drove away.

I'm guessing prices have gone up since and that I caught it just at the right time.
 
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