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Full Version: Continue with 1/2 Poly or try and snug 1"?
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Hey all,

I am planning the next layer in the van for insulation on the walls and ceiling for this weekend now that the weather will be a little warmer. I am going to 1" poly in the roof of the hightop and was planning a 1" poly on the sides of the van as well to go out to the edge of the ribs. The problem is the curve the van and getting the 1" to conform to it. Am I better to go with two layers of 1/2" there so I can still have the flex or will I be losing a lot of R-Value going with 2 1/2 layers vs. a 1" in. layer. Your thoughts???
I would go with the thinner so you can conform easier. I don't think you will be losing any R-value. anybody else have an opinion. highdesertranger
(11-30-2015, 09:03 PM)highdesertranger Wrote: [ -> ]I would go with the thinner so you can conform easier.  I don't think you will be losing any R-value.  anybody else have an opinion.  highdesertranger

I agree totally, two 1/2 inch sheets will work fine. I used 3, 3/4 inch sheets on the roof of my cargo trailer because it has a strong curve. Has never been a problem.
Bob
If the polyiso is foil wrapped, you may even gain R value when going multiple layers.
Thanks for the feedback. I figured sticking with the 1/2 and using multiple layers was the way to go. I'll look at the 3/4 as well.
I am also insulating, and to fit to the curvature I been cutting into smaller pieces. my roof is very curved in my nissan van. If I didn't do it that way, I wouldn't b able to completely stand up in the middle of the van.

[attachment=5357]
Try to stagger and tape all your seams, if you can.
Hi
I think the two layers of half inch is fine -- you won't lose any R value.

But, some people use 1 inch and hold them in place with springy sticks until the adhesive cures -- this also works fine.
Picture down this page of the springy sticks: http://www.buildagreenrv.com/design-and-...nsulation/  down the page after the spray insulation section.

Gary
(12-02-2015, 09:20 AM)GaryGary Wrote: [ -> ]Hi
I think the two layers of half inch is fine -- you won't lose any R value.

But, some people use 1 inch and hold them in place with springy sticks until the adhesive cures -- this also works fine.
Picture down this page of the springy sticks: http://www.buildagreenrv.com/design-and-...nsulation/  down the page after the spray insulation section.

Gary

well it appears us gary's have zero imagination when it comes to screen names
At the local LOWES the price difference between two 1/2 inch and one 1 inch sheet of foam block insulation was about a dollar. Since I didn't have a buck more to spend I acquired the 1" foam block and it was hard to conform. Go with the half inch if you have the slightest curve, spend the extra buck on two sheets of 1/2 inch unless you do not have the extra buck. Also do not grind out polyurethane only to replace it with rigid foam block, it's like cutting a hole in the wall only to fix it with the same material the wall was made out of.
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