Be sure the cellulose has air movement (not just behind a baffle) above it to dissipate any moisture it gains; http://www.buildingscience.com/docum...+in+flat+attic
Just add f.b. in the tight areas to get a higher R-value per inch, then Roxul as cellulose will slide down (as you can't dense-pack it) leaving weak areas. ADA the ceiling drywall also.
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