In a tiled shower installation where the CBU meets the ceiling, what does one use to finish the corner at the top of the wall between cbu and ceiling drywall? The wall tile runs up to the ceiling with in the shower.

My first shower I used drywall paper and mud at the top corner and tiled up to the ceiling. (all other cbu joints I used modified thinset and fibreglass mesh tape) However this is a high moisture environment and I have seen the drywall of the ceiling go goofy in showers before.

There's no need to tape the ceiling joint as long as your tile is going right up to the ceiling. This joint area is caulked once the tile is completed.

The ceiling should be fine as long as a good quality paint is used.(not regular flat ceiling paint) An appropriately sized exhaust fan is also reguired to get rid of excess moisture.

this is probably overkill... but i put redgard on the drywall above my shower since i had a lot left over.

i think the point is to make it mildew proof, not waterproof (this area is not exposed to direct water). redgard comes with anti-mold technology mixed right in so i thought it would be more than sufficient.

i will paint it white a few times and then go over with colour (no tiles up there for me).

Knucklez

I think Redgard is paintable, so that should work for you. If you can get the texture smooth that is.

The curb, walls, and floor area near the curb (ditra on thinset on heating wires) will all have redguard. I scraped the old ceiling "popcorn" off and will skim coat for flat finish. I wonder if I should redguard and then skim coat and paint. Probably best to skim coat and then redguard to protect the drywall mud from moisture. How does the paint go on that redguard, assuming one gets the redguard painted on flat?

There are special paints made for high moisture areas such as bathrooms. The one I know best is Perma-White by Zinsser. http://www.zinsser.com/product_detail.asp?ProductID=35

Jaz