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Old 01-19-2010, 04:55 AM   #1
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faced or unfaced insulation for flat roof?

I have gutted my 3rd floor and have reframed it now I need to add some insulation. Any ideas on which kind of insulation would work best? I plan on putting up 1/2 drywall. Also I live in the NE so cold winters and hot summers.


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Old 01-19-2010, 07:08 AM   #2
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What size are the joists , how much room for insulation ?


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Old 01-19-2010, 02:04 PM   #3
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According to this, with a 191 zip, you need R-38 in the attic: http://www.ornl.gov/cgi-bin/cgiwrap?...le/ins_fact.pl

The best would be spray closed cell foam, at about R-6 per inch: http://www.henry.com/fileadmin/pdf/H...l_Brochure.pdf

A special glass batt insulation, R-38C is used with 2x10 roof rafters. (Or furr down the existing rafters).
Rather than glass batt, I would use : http://www.buildinggreen.com/auth/ar...&printable=yes

You could also use cellulose and rigid foam board on the rafters to get required R-value and a vapor retarder in one.

You may/not require a vapor retarder because some B.D. state you need 12” of air space above the insulation with one. (Typical attic) http://www.buildingscience.com/docum...ecommendations

You might be able to use vapor barrier paint, ask your local B.D.: http://www.ornl.gov/sci/roofs+walls/...on/ins_18.html
Is the roof vented?

Be safe, Gary
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Old 01-20-2010, 08:11 AM   #4
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The joists are 8" and I have about 11" of space to the end of the studs that will be used for the drywall.
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