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Has anybody used this?i was thinking about it for some of the harder to get places where polyiso won't conform to the shape, like the rear corners and the structural along the top on both sides. Im referring to a chevy van. http://www.globalindustrial.com/p/building-materials/pipe-tube-bending-cutting/pipe-and-tubing-insulation/insul-sheet-s2s-1-23648?infoParam.campaignId=T9F&gclid
(01-20-2018, 08:34 AM)Scout Wrote: [ -> ]Has anybody used this?i was thinking about it for some of the harder to get places where polyiso won't conform to the shape, like the rear corners and the structural along the top on both sides. Im referring to a chevy van. http://www.globalindustrial.com/p/building-materials/pipe-tube-bending-cutting/pipe-and-tubing-insulation/insul-sheet-s2s-1-23648?infoParam.campaignId=T9F&gclid

This material has a thermal conductivity of about 0.04 W/m-K while polyiso is 0.023 W/m-K, or about 70% higher.  In order to get the same R value as a polyiso sheet, you need 70% more thickness.
So for a flat area, use poly-iso


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Trying to get a 100% coverage in a cargo van is an unrealistic expectation. If you can insulate 90% you're ahead of the game. Don't worry about those hard to get places!
Depends on your needs.

Camping in the snow, running out of propane requires making a long trip back to civilization more frequently

would motivate me to get it right the first time, very difficult to tweak it later.

In that case:

Polyiso for the bulk of it, make gaps as small as possible

then two-part closed cell spray foam so as close to a sealed envelope as possible, all thermal bridging eliminated,

maybe a final inside half-inch skin of foam that can bend with a heat gun

heavy duty plastic vapor barrier well taped up

In total ideal thickness (if enough room) is 3" on the walls, 4" ceiling 2" floor

then the interior skin.

MaxxAir or Fantastic Fan for controlled venting.

And yes, compromises are often called for.
(01-20-2018, 04:59 PM)Almost There Wrote: [ -> ]Trying to get a 100% coverage in a cargo van is an unrealistic expectation. If you can insulate 90% you're ahead of the game. Don't worry about those hard to get places!

Im just thinking if i leave any metal exposed i'll get condensation and then mold if it drips down behind things.Its more for that than losing heat. But your right it would be hard to get 100% coverage.
Then focus on getting a good innermost vapor barrier rather than a complete insulation envelope.

Well controlled ventilation is also critical when the space is otherwise well sealed, especially when burning unvented propane. High-cfm helps too when it's hot, especially hot and humid.
(01-20-2018, 09:16 PM)John61CT Wrote: [ -> ]Then focus on getting a good innermost vapor barrier rather than a complete insulation envelope.

Well controlled ventilation is also critical when the space is otherwise well sealed,  especially when burning unvented propane. High-cfm helps too when it's hot, especially hot and humid.

When you say innermost does that mean towards the inside of the van? Should that be plastic sheeting maybe just behind the panels but over the polyiso?
Yes, over any insulation and just under whatever you're lining the inside with.

Reflective mylar is often used, but useless there.

Heavier plastic just helps prevent punctures & tearing, no need to go overboard, many just use painters dropcloth. And vapor barrier tape is fine, some go with stronger duct tape, but pricey.

I know others don't bother, but even a 1/2" thin sheet of decent foam covering over any exposed steel will help prevent major thermal bridging when it's bitter outside, reduce heating fuel usage long-term.

Ignore if following the 60's
I've lived in vans for well over a decade full-time and travelled in them year round since 1975.

In all that time the ONLY time condensation was ever a serious issue was camping in an uninsulated van in 2 feet of snow. Then we had condensation. It caused no damage whatsoever because it was only short term. It won't cause damage unless you  have broken paint on the inner walls of the van and you cause the condensation repeatedly.

The rest of the time, the worry that someone who does not live full-time on the road has is vastly overdone. If you plan on living in the van full-time in a cold, snowy environment like spending the winter in South Dakota then go ahead and plan for condensation reduction and mitigation...otherwise it is a non-issue.

Better mitigation like ventilation several times a day and prevention of large amounts of condensation will go a whole lot further than trying to install a vapor barrier. There is a reason, and it's not lack of expertise and cheap construction that NONE of the RV produced commercially have a vapor barrier installed.

You are in and out of the van multiple times a day, the air transfer of opening and closing van doors equalizes the temperature and therefore the humidity without any further action.

Use of a vapor barrier, IMO, is uncalled for and in a lot of cases, causes more harm than good. When I say that it is because a good vapor barrier (100% sealed) will prevent natural humidity caused by cold air outside meeting any kind of warmer air from dissipating. It will  collect on the cold side of the vapor barrier - that would be between the van wall and the vapor barrier where is will cause problems. An incomplete vapor barrier won't do any good so it's just a waste of time, effort and money. Doing a 100% vapor barrier in a s&b home is difficult enough and has proven to be problematic in other ways, achieving one in a van would be almost impossible.

Unfortunately a lot of people with no actual on the road experience and only text book or youtube/google knowledge try to envision what they think are possible scenarios and then offer advice based on what they think instead of what they have actually experienced.
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