# cement board behind tile ceiling in showers?



## ntsllc (May 5, 2011)

would it be a good idea to put cement board on the ceiling of a shower or would it be fine to just tile right over the existing primed drywall?? Its an 8' ceiling and will be above water line. Let me know what you think, could save the home owner some money by not having to tear drywall down...


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## angus242 (Oct 20, 2007)

Use a membrane. Moisture, particularly steam, will rise and hang out be the ceiling.

You can use a fabric or liquid membrane. I hope you use membranes for the rest of the shower too....


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## tazmanian (Jul 22, 2010)

i agree with him - use a membrane - if you want to be double sure you can use backer board above with a membrane and you will have no sleepless nights


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## Remodelor (Nov 5, 2010)

Membrane systems are the highest quality. That said, more than 95% of the showers in America probably have a simple painted ceiling over them and the water vapor doesn't destroy them.

I know I'll probably catch **** for not suggesting the absolute best possible solution, but in all reality, unless it's a sealed steam shower, you'd probably be fine installing the tile directly onto the primed sheetrock if it's already there.

If you are using hardibacker or another CBU for the rest of your shower substrate, I would suggest something that is a vapor barrier like Kerdi / Wedi / Densshield with Silicone on the seams and screwheads. Hardibacker lets moisture through and can still rot out. I just pulled out a hardibacker floor in a bathroom a month ago that was the consistency of wet newspaper.


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## lh66 (Apr 18, 2011)

Yeah Membrane systems would be the best


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## TBFGhost (Oct 9, 2008)

Remodelor said:


> Kerdi / Wedi / Densshield with Silicone on the seams and screwheads.




Silicone?


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## Remodelor (Nov 5, 2010)

TBFGhost said:


> Silicone?


Perhaps I was unclear. Not with Wedi or Kerdi obviously, but yes with Densshield. The manufacturer installation instructions say that seams can be filled with any flexible sealant. I use 100% RTV silicone.

http://www.google.com/url?sa=t&sour...FK_tDMvY8TJzLOReg&sig2=aQ2TsyuDFgcs2G-44G9T2g


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## remomarc (Jul 10, 2007)

YUP!:thumbsup:


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## remomarc (Jul 10, 2007)

I didn't see it was two questions so:
YUP! & NOPE!


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## fiveash (May 23, 2011)

I personally wouldn't put tile anything but concrete or backer board.


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## angus242 (Oct 20, 2007)

fiveash said:


> I personally wouldn't put tile anything but concrete or backer board.


Waterproofed?


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## CrpntrFrk (Oct 25, 2008)

fiveash said:


> I personally wouldn't put tile anything but concrete or backer board.


So on an 8" back splash you would rip the sheetrock out 8" above the counter and install backer board?

To each their own but that seems a bit far fetched.


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## angus242 (Oct 20, 2007)

The original question was about tile on a shower ceiling. I assume the CBU comment was in regards to that.


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## thom (Nov 3, 2006)

angus242 said:


> The original question was about tile on a shower ceiling. I assume the CBU comment was in regards to that.


15 years ago I tiled the walls and ceiling of a bathroom in my own house with marble. I covered the walls and ceiling with cbu (Hardi) then tiled them, it worked fine.

I did the ceiling first (diagonal checkerboard). To support the ceiling tiles I had rails screwed to the walls that supported 2X4's that ran wall to wall. Each tile was blocked to the ceiling from the 2X4's below them. It worked fine, was simple and easy. After the thin-set cured I removed all the supports and rails and did the walls.

In 15 years there has been no problems with the installation.


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## greg24k (May 19, 2007)

I don't think you allowed to use cement backer board or mat-gypsum backers on the ceilings in the shower area. 
If you using 1/2 water resistant gypsum backer board as the base for tile, the framing should be 12" OC. If 5/8 is used, then its ok to use for 16" OC.


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## jarvis design (May 6, 2008)

greg24k said:


> I don't think you allowed to use cement backer board or mat-gypsum backers on the ceilings in the shower area.
> If you using 1/2 water resistant gypsum backer board as the base for tile, the framing should be 12" OC. If 5/8 is used, then its ok to use for 16" OC.


You may want to double check that. I've being putting cement board on ceilings for years...wouldn't dream of using WR drywall in a shower or above a tub if it's being tiled.
Permabase, my brand of choice, can be installed on 16" centers on ceilings but you gotta frame between joists on the perimeter.


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