[Greenbuilding] Mold questions - Isocyanurate R value

[Laren Corie]

 "Lawrence Lile" <LLile at projsolco.com>

> I have understood that the foil faced insulations, which start out at a
> really high R value, end up outgassing the blowing agent and then
> losing R value over the years.  All foams have this problem, but the
> polyisosyanurate has the problem to a greater degree.  This comes
> from a contractor

Hello Lawrence;

 Your contractor suffers from the same confusion that is rampant
about cellulose settling.  Just as cellulose is rated, and installed for
its settled depth and R value, and you usually end up getting higher
R value than you pay for, the same holds true for isocyanurate. It
is also rated at its final, stable R value, and during the initial years
has a higher insulation value than it is rated at.   In the old days of
R7.6 iso, it was estimated that for the first couple of years, it might
have been as high as R11 or 12. That time frame can be extended
by using aluminum tape over all of the exposed edges, and penetra-
-tions, however, it is near impossible to seal them all. With the new
system (R 6.5) there seems to be no good information on what the
initial R is, or how long it will take to stabilize.   But, definitely, the
rated figure is the stabiled R, not the initial R.  There is no reason
for concern about it ever dropping below its rated R value.

-Laren Corie-
Natural Solar Building Design Since 1975
www.LarenCorie.com

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