My new split level home has approximately 1300 square feet of attic space (2x6 - 16" on center with 1/2 drywall) + a vaulted ceiling over the living room (approximately 39 x 14 room, vaulted from 8 to 20 feet). Attic insulation is about 6" of fiberglass batt (R19), vaulted ceiling insulation is unknown (estimate R21) I would like to beef up the attic (1300 sqft) to R50 to R60 using cellulose. I am concerned about overloading the sheet rock. Any suggestions on how to add 12 to 15 inches of cellulose with out creating a new problem? I would also consider moving the insulation to the roof deck, if that makes sense. Also I am considering lowering the vaulted ceiling to increase the insulation levels to match the attic. Thanks

At 16" o.c. joists R50-60 cellulose isn't much of problem for the sheet rock. Depending on span there may be issues with dead-weight loading of 2x6 joists.

If the joiists are up to snuff for the span and you're concerned about sheet rock sag, fluff the fiberglass or fill cellulose the joist tops and put down a deck of half-inch OSB (detailed as an air barrier) to carry the load of the cellulose. With an OSB floor you can run it up to R100 if you have the space, if the joists can handle the load.