Standard drywall is not appropriate in wet or high-humidity areas. Bathrooms and kitchens require moisture-resistant board — either fiberglass-faced gypsum (DensArmor or similar) for areas with humidity but no direct water, or cement board (HardieBacker, Durock) directly behind tubs, showers, and tile surround installations. Purple board (moisture- and mold-resistant gypsum) works well in laundry rooms and bathrooms without direct water exposure. RainFire Builders specifies the correct substrate for every location — not a one-size-fits-all product across the whole house.