bathroom remodel

igneous

I plan to remove the existing white 5x5 subway tiles in the shower and around the tub and replace with 12x12 tiles to be determined later. I also plan to have installed a glass shower surround. I have watched entirely too many "Holmes on Holmes" shows to go into this blindly. Am I in the right forum to ask the following questions:
What specific line items should I expect in a contract?
Will the wallboard need to be replaced after removing the existing tiles, assuming it is in good condition? I intend to do most if not all of the demo.
Or, should I replace the wallboard with cement board?
What kind of materials should I use to avoid any water damage in the future? (hopefully this is a non-issue).
If I missed any important points, please feel free to identify. Thanks.

Bud Cline

Five by five tiles aren't subway tiles but they are apparently history so it doesn't matter.

Until you begin to remove the existing tile you are only kidding yourself by speculating you can save the existing substrate.

What is the existing substrate made of?

Remove the tiles then continue your thought processes. For now, plan to replace the wallboard.

igneous

Thanks for speedy reply. I don't have the terminology down, but the idea of replacing the substrate was high on my list.

(Q)

Just finished a total bath remodel myself. You should just put up new wall board, then you dont have to worry about anything- trust me. Removing the old tile will most likely destroy most of the board anyway. Water damage is a BIG TOPIC! I used cement board with 3 layers of Redgard over it - then you dont need any plastic "vapor barrier" I would look into this a lot if I were you- you dont want mold or rot problems down the road. The thinset for the tile sticks to it really well too.