.

All seams must be taped and finished with thinset.

Thanks Celadon. Is this only essential in the wet areas? I noticed the other seams in the bathroom where the wall meets the ceiling are also not taped. In those areas it's greenboard meeting greenboard.

In drywall installation, inside corners always get taped.

Wait: Is that cement board with drywall mud on top? Can you post pics of the whole area, please, but from further away?

Sammy, shower enclosure is cement board, rest of the bathroom is green board, including ceiling. Ceiling is mudded, cement board joins have been thinsetted. Corners are taped. Horizontal seam between wall and ceiling all around the bathroom is not.

Yes those corner joints must be taped and spackled. I would probably spackle those with thinset. What is your tile setter using for waterproofing?

I wouldn't worry too much about the wall/ceiling juncture. It's not going to get wet or moldy there. And I can tell you this from considerable experience, based on having demolished hundreds of old bathrooms: you never seen mold or water damage there. Ever. It's always down at the base of the tub or shower. That's where great care needs to be taken to ensure a waterproof seal at all junctures.

The drywall wall-to-ceiling joints elsewhere in the bathroom need to be taped, though, as they will crack if not taped and mudded. But this is not a waterproofing issue.

Yes, it is very important to seal the base of a tub or shower well. But at the top of the walls? Nah. They're fine. If the tile setter is competent the tile work will be snug to the ceiling and caulked there.

"But this is not a waterproofing issue."

Not saying waterproofing for that joint I am saying for over the cement board where there is no waterproofing yet.

All joins are required to be taped and mudded.

This was all very useful, thank you! Since there seems to be a structural element to the tape, I'll just go back and add tape at the wall-to-ceiling junctures around the bathroom. Any tape preference for the bathroom drywall, paper or mesh? Then I'll see if the tiler will take care of the shower enclosure area which will need thinset. Home Reborn, thanks for sharing your experiences. Millworkman, waterproofing will be with redguard. Tiler will do this.