[Greenbuilding] Green real estate market -- spray foam, and geothermal

[John Messerschmidt]

Hi All,

I had Icynene sprayed on a small extension last summer and noticed one or
two small areas where the foam separated from the wood studs.  This happened
on the inside of the wall.  I don't know how far into the cavity it
separated.  Now, when we get a frost the roof of the extension is nice and
frosty, while the main house's roof has melted.  

Later in the fall, I sprayed Tiger Foam on one cement block wall of our
garage/wood shop to test the product, which boasts a 7+ r value.  I set the
studs back 1" from the wall.  The plan was to spray 1" of the foam for the
vapor barrier, also giving me an r7, and then using cotton batt insulation
between the studs for an additional r13.  Also, the cotton batt was half the
cost of the Tiger Foam.  The Tiger Foam instructions were easy enough to
understand so that I was able to do it all without incident and was very
satisfied with this approach.  I would improve on this by ordering more
Tiger Foam, because it didn't cover as much as they claimed.  This may be
due to the overspray on the sides of the studs, the ceiling and floor, and
some areas where it went on a little thicker than 1".  

I'll use this strategy for the rest of the garage, but I'd really like to
try out the spray-on wet cellulose on the rest of the house as the cheapest
and most eco friendly insulation solution.  

One question, is the cellulose an effective vapor barrier like the foam is?



Cheers,


John 






-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Keith Winston
Sent: Thursday, January 11, 2007 6:01 PM
To: Greenbuilder list
Subject: Re: [Greenbuilding] Green real estate market -- spray foam,and
geothermal

Hi Steve,

All (professionally installed) spray foams are, to my knowledge, 2-part 
polyurethane foams. Many foams are sold as such, and biobased/soy are 
just 2-part PU with some portion of the polyol part replaced by 
vegetable-oil-derived polyols, amounting to 10-30% of the final product. 
I believe Icynene is an open-cell polyurethane. All the foams are fairly 
horrific in terms of safety/exposure during installation (they require 
using an external-air breathing apparatus, for example, not just a 
respirator), but most sources suggest that they are largely vapor-free 
after they've cured, in a few days. Many of them used to use terrible 
blowing agents, I'm not sure that any of them do now. Many people think 
about oil-based polyurethane floor finishes and shudder with dread at 
using them, but water-borne polyurethanes (which includes sprayed) don't 
have the same nasty solvents.