In a kitchen there is no advantage to using hardiboard or cement board if the drywall is already there, and you will just add time and expense. In a bathroom it makes sense because it doesn't mold, or at least, not as easily. Neither does it deteriorate in moist conditions. But even here ito is only necessary around the tub or showroom enclosure. Tiling the walls of a bathroom can be done straight on the drywall.
4/15/16 at 4:27pm