[Greenbuilding] PU & adobe

[Rob Tom]

On Thu, 06 Sep 2007 08:21:58 -0400, wmdorsett at sbcglobal.net  
<wmdorsett at sbcglobal.net> wrote:

> Vadurro, Rob, EMNRD wrote:

>> PU foam is vapor permeable and waterproof, good
>> characteristics to have, and it seems to stick to adobe (and everything
>> else!) just fine. I've not heard of any long term problems,


I can't take the time to look it up right now but I'm pretty sure that the  
vapour permeability numbers for pee-you foam straddles both sides of the  
"one perm or less" rating which classifies a material as being effectively  
a vapour barrier.

The numbers 0.4 to 1.6 perms come to mind but it wouldn't hurt to check.

So for a 4-inch thickness of pee-you foam (as the OP had mentioned), I  
think that one can safely assume that the foam will not be vapour  
permeable at all.

The problem (WRT fire) with most foamed plastic insulations is not so much  
the potential for flame.

It's the smoke and to a lesser extent, the hazard that is created by the  
molten material dripping onto exposed flesh. I'm not sure if these would  
apply to pee-you foam so it's another thing that should be checked.

In most fires, it's the smoke that kills, not the flame.
Being burned by molten chemicial goo dripping onto a buildings occupants  
may not kill 'em, but it wouldn't be pleasant either.

-- 
=== * ===
Rob Tom
Kanata, Ontario, Canada
< A r c h i L o g i c  at   C h a f f Y a h o o  dot  C a  >
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