Quick question for the pros out there. My previous shower (installed in the 90s) had full length fiberglass panels adhered to the drywall behind it. I am planning to replace these and the drywall behind them. I plan to use cement board in the main shower area, but have a question on where to put the seams between the cement board and the drywall. Should this seam be as close to the end of the new tile installation as possible, or can I place the last tile over this seam?

Thank you!

2 Answers 2


You can bury the joint under the last tile assuming it's in a mostly dry location. It's a great way to be sure you have a good tape joint and reduce drywall finish work and painting.


The answer here is "it depends". But let me give you some pointers to help.

  1. Cement boards for showers and tubs should run to be about 6' high. This is considered the "wet" area and could be met by inspection.

  2. That being said, if you put it at 5'10" I doubt this matters. Also if it is easier to just run it to the ceiling, do that.

  3. If I am tiling to the ceiling I run the cement board to the ceiling because it is easier.

  4. For a tub you need to run the cement board to the outside of the tub. For a shower just make it past the door.

  5. Standard tubs are 30". Standard concrete boards (I would use Hardiebacker for shower) are 3'x5'. Meaning if I stand up 1 sheet I have meet both my width and height requirements.

  6. Most concrete board - including hardiebacker - will not be the exact same depth as your drywall. So there will be a little bump.

  7. You will fix this using concrete board tape and thinset. Before you tile, using your thinset to flatten out these areas and cover the tape.

  8. Then when you tile your last row - at least - should be covering the concrete board to drywall transition. This is the best way of doing it and allows you to adjust depth with thinset.

  9. If you aren't tiling on your concrete board - you should be - and your concrete board extends past the wet area and you aren't tiling it. You will have to skim coat the entire board with joint compound. You cannot paint concrete board or it will look completely different than the rest of the room and have an odd texture.


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