It may seem obvious, but drywall should not be used to back the tile in the shower or bathtub enclosure, as sheetrock breaks down in the presence of moisture. Using drywall as a substrate for the tile is a recipe for potentially costly repairs (and probably after a relatively short time, too!). Certain waterproofing products (such as Schulter Kerdi) offer a warranty on their waterproofing capability even when drywall
is the substrate, but unless you have such a product, avoid putting drywall in direct proximity with the wet area of the tub or shower. Feel free to drywall the rest of the bathroom (outside of the wet zone), but consider using a mold-resistant greenboard as the bathroom in general is a high-humidity environment. This is especially true nowadays as time spent in the shower/bathtub has increased considerably thanks to the arrival of products like Jacuzzi tubs and rainfall shower heads. These products encourage people to spend more in the bathroom as a calming oasis rather than the shorter, more business-like showers of
yesteryear. For this same reason, avoid using paper tape in the bathroom. The paper can be a source of food for mold, encouraging it to grow. Be sure to use mesh tape in damp environments like the bathroom.
