Is dry wall an insulator?
While drywall, or gypsum board, does give insulation value it is
not a high amount, a 1/2" piece of drywall will only raise the
r-value by .45, if you are looking to improve the insulation of a
wall you are much better off using rigid foam insulation. An
extruded polystyrene board, that's Styrofoam, of 1" thickness gives
you an R-value of 5.00, which is over 5 times greater per inch than
that of drywall. You can further improve the insulation value of a
wall by add some kind of batt insulation in-between the studs.