Help with tile ceiling advice

[Dambr]

After reading the library about greenboard I am not sure about using it in the shower ceiling.
My tile man told the carpenter to put greenboard in the shower ceiling and prime it. He installed it today and I question him about it since I am having tile installed in the ceiling.
The tile man is putting cementboard everywhere else that he is going to tile.
I don't know if the tile man remembered that I wanted the ceiling tiled. I am reading that the problem with greenboard in the ceiling is that it is too weak.
Please advise me so I can call my tile man and be knowledgeable with what I am saying.
The tile man specializes in showers and has done work for high-end developments.
Thank You, Diane

[jgleason]

I'd skip the greenboard on the ceiling, if you stay with it you'll need support 12"o.c. You would be alright with 5/8" drywall I think. Of course, I did my shower with Kerdi, including the ceiling (steamy showers are the norm).

[Davy]

Hi Diane, I think you're okay with greenboard on the ceiling, it helps if the joists are 12 inches apart instead of 16, gives him more to nail to. I would make sure he doesn't stick the tiles to the greenboard on the walls, the ceiling is fine. If he is going to put up CBU on the walls be sure he puts up felt paper or poly on the greenboard first.

[Dambr]

Thank you for the info. My husband said the joists are 24 inches.
If that section of greenboard is taken out what would be the best to put in?
Also would the greenboard be OK in the rest of the bathroom ceiling?
Diane

[cx]

The greenboard is not acceptable at all with that joist spacing, Diane, even if it's 5/8ths greenboard. Greenboard tends to sag on ceiling applications, which is why the code-required joist spacing is closer for its use.

And all half-inch CBU has a maximum spacing of 16 inches on center.

Regular 5/8ths inch sheetrock is acceptable for ceilings with max 24 inch spacing, but tiling on it is a little questionable to my mind.

I think the easiest thing for you to do is remove the greenboard and add joists between the existing in the area to be tiled. This shouldn't be a big chore and then you can pewt anything you wanna pewt up there.

My opinion; worth price charged.

[Dambr]

Just wanted to thank all who responded to this thread.
When my carpenter arrived yesterday, I showed him all the info on greenboard
plus GP recommendation. He then phoned Georgia Pacific to talk with a tech person. When he hung up he said the tech advised a spacing of 16 inches.Our joists are 24 inches.
I told the carpenter that the tech had to have given incorrect info. I went to the site and found the discrepancy. The carpenter used 1/2 inch greenboard and the code is 12 inches for that. If he had used 5/8 greenboard it could be 16 inches. So he removed the section above the shower and cementboard will go there. The rest of the ceiling had joists put in between the existing joists. I am very thankful you responded to my question so quickly that the error could be corrected. Diane