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<DIV><FONT face=Arial size=2>Yes it does.There is a rapid (on the order of
months) change as air diffuses in. A longer change occurs as the blowing agent
diffuses out. Some manufacturers give the R value after a certain time
period.</FONT></DIV>
<DIV>Leon R. Glicksman<BR>Professor of Building Technology and Mechanical
Engineering<BR>Massachusetts Institute of Technology<BR>Room 5-418<BR>Cambridge,
MA, 02139<BR>Phone 1 617 253 2233<BR>FAX 1 617 253 6152<BR>E-mail <A
href="mailto:glicks@mit.edu">glicks@mit.edu</A></DIV>
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<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: black"><B>From:</B>
<A title=mrzoeteman@FTCH.com href="mailto:mrzoeteman@FTCH.com">Zoeteman, Mark
R.</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=BLDG-SIM@gard.com
href="mailto:BLDG-SIM@gard.com">BLDG-SIM@gard.com</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Friday, February 24, 2006 4:41
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> [BLDG-SIM] Insulation
Values</DIV>
<DIV><BR></DIV><!-- Converted from text/rtf format -->
<P><FONT face=Arial size=2>Does thermal conductivity of polyisocyanurate roof
insulation change over time?</FONT> <BR><FONT face=Arial size=2>Will the
R-value decrease over time? There seems to be conflicting information about
this.</FONT> </P>
<P><FONT face=Arial size=2>Mark Zoeteman</FONT> </P><BR><PRE>
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