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Full Version: Polyiso is open cell foam?
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I haven't used polyiso yet, I've done all my van conversions with plain old closed cell white styrofoam. A friend told me that polyiso is an open cell foam and therefore is susceptible to moisture, whereas the closed cell will not absorb moisture.

Any experienced users that can chime in would be welcomed.
A google search on polyiso insulation turned up a link to a trade association of polyiso manufacturers.

They say polyiso is CLOSED cell foam.

I don't know the answer to your question. I do know all the Polyiso I've seen has heavy cover on both sides so even if it does absorb moisture, it's not going to

I've used lots and lots of the standard white styro and it would be my last choice for insulation. The pink or blue styro are far, far better products. The literally were designed to be buried under house slabs to insulate the basement. That's a tough product!!

Now I consider polyiso better and what I recommend as a first choice. Only use the white if you can't afford better or can't find better.
it's closed cell. highdesertranger