What type of sheathing- OSB or plywood? Any block in that wall?; http://publicecodes.cyberregs.com/ic...016_par015.htm
PS. You can also cut 1-1/2" wide strips of XPS for on the studs/plates before the drywall...ADA the drywall to limit air movement.
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!