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
Clothes taking longer to dry?
Clean the dryer screen in HOT water if using fabric softener sheets.
They leave a residue that impedes air-flow, costing you money.
Clean the ducting in the last six months? 17,000 dryer fires annually!