The way we approach Wall and Floor Tiling design and renovation is to ask for the requirements like budget for the project, and we then tailor a budget for individual needs with better. A typical plan goes like this.
1. Figure out the space you have to work with by measuring floors, walls and ceiling (in case).
2. Checking the conditions of the substructure and walls behind the existing bathroom.
There is a good chance that once the interior is stripped out & there may be issues with rotten flooring. For example, some builders used yellow tongue boards and when water came into the equation they would rot.
3. Water-proofing -when the membrane is to be applied you need to make sure that it is compatible with the tile adhesive as well. The builder should have planned your project & follow correct building code practices. After a thorough inspection, we can then give your new bathroom the best waterproofing membrane for adequate protection against moisture and rot.
One of our bathroom renovation project, we recently inspected for one of my clients in the Eastern Suburbs of Sydney had no waterproofing system at all! All the timber studs in the wall were rotten and termites had infested the house due to the moisture levels. And we did all it required with no additional charges, except for materials.