Home depot R-30 shows 58.67 total square foot coverage divided by the width of batt = 1.33 = 44.11 divided by each one is 4' long = 11 pieces
Keep in mind, R-30 is one of the lowest density batts out there at 0.57# per cubic foot- compress it to R-26 (medium density) or further still to R-15 (high density, pp.41;http://www.huduser.org/Publications/pdf/walls.pdf
), compare Roxul at >2lbs/ft3; http://www.roxul.com/files/RX-NA-EN/...th%20steel.pdf
Air seal the attic first, and use a housewrap over the low density batts to prevent wind-washing degrading you thermal barrier.
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!