Durock Cement Board - Bathroom Ceiling

bsticksAugust 16, 2007

Hi there, I don't mean to post this twice but my other post seems to have not made it.

My question is, how and what do you use to finish off a ceiling? I have the fiberglass tape and thinset to finish off the joints, but what about the rest of the board? I have some pitting in some places and it looks a bit rough to just paint over. Should it be floated with thinset like you would a house foundation or is joint compound an option then just sand off to a smooth finish?

Thanks and sorry if this shows up 2x!

Bsticks

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ventupete

I guess my question is why you have cement board on your ceiling instead of drywall? Cement board is usually used as a base for ceramic or stone tile - never seen it used as the finished surface. It is very rough, and thinset mortar is not going to give you a smooth finish. You might be able to skim coat it with joint compound but it's a lot of work, especially on a ceiling. Have you considered putting a layer of drywall over it?

    Bookmark   August 16, 2007 at 5:04PM
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bsticks

Hi and thanks for answering. I had a mold problem that required a remediation to my second floor. Pinpointed to my bathroom. It's an 8'x 8' space and exhaust fans just couldn't get the job done. It was suggested and my code official in my town said put the time in and use the cement board. Long answer to why it's on the ceiling.

Actually about 60% of the space is pretty smooth and the 40% to skim coat are spots on only 5 boards. I just wanted to make sure that joint compound would bond well to the boards.

Thanks again!

    Bookmark   August 16, 2007 at 5:53PM
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ventupete

Almost any finish material (plaster, stucco, drywall compound, etc) will bond well to cement board. A friend of mine put cement board in his bathroom and then decided to only tile it part way. He skim coated the rest of the wall with drywall compound and it ultimately came out well. However, he had to put a second coat on to achieve a smooth finish - don't know if it was because he didn't do a good job on the initial coat or because the cement board absorbed the compound unevenly.

    Bookmark   August 16, 2007 at 7:19PM
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bsticks

Get information. Thank you very much...

    Bookmark   August 16, 2007 at 7:28PM
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kboeckman

My husband and I are going to tile our bathroom. What is the usual size of grout line for a 13 x 13 tile and
what is the minimum width the can be used for that size of tile.

    Bookmark   January 16, 2009 at 8:07AM
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homebound

3/16 or even 1/8 if the floor is fairly flat and even. (BTW, 3/16 often appears larger than that when finished, given rounded tiled edges, etc.) Other views may differ.

    Bookmark   January 16, 2009 at 11:01AM
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bill_vincent

The only view that SHOULD differ is if it's rectified porcelain. Other than that, 3/16" should be the minimum grout joint, unless you want to take the time (or pay your installer a little extra so HE can take the time) to fool with it and make it come out nice with the 1/8" joint. But be forewarned-- due to sizing, some culling may be necessary for the smaller joint.

    Bookmark   January 18, 2009 at 8:32PM
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brickeyee

"It's an 8'x 8' space and exhaust fans just couldn't get the job done. It was suggested and my code official in my town said put the time in and use the cement board."

You needed a larger exhaust fan.

Cement board was overkill.

Skim the surface with a setting type joint compound, prime and paint.

    Bookmark   January 19, 2009 at 10:57AM
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mightyanvil

Why would someone tag a different question on to a year and a half old thread and force people to read the old one to find the new one? That makes it necessary to read the date of every thread before reading it. Am I the only one who finds this inconsiderate?

    Bookmark   January 20, 2009 at 8:35AM
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msjay2u

I did my bathroom over because I also had mold in the walls. The bathroom was added in the 40's. I used the smooth cement board because I wanted the option to tile everything if I wanted PLUS I had a piece of cement board left outside in the heat, sun, rain, sleet, and snow for months and it never warped, came apart or anything. Granted, cement board is usually only used under tile but I think using it instead of drywall in the bathroom was a smart idea. We wound up only tiling the shower area tub to ceiling and painted the rest. If I change my mind and want to put in tile on the ceiling or on other parts of the wall it is an easy fix. There was a skim coat put on the cement board and it is very smooth. You just have to get someone who knows what they are doing to skim the walls. It looks just as good as drywall, if not better, and you can not tell the difference at all.

Hope this helps

    Bookmark   January 20, 2009 at 1:57PM
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davidro1

I agree with the above. CBU can be good as an anti mold surface.

    Bookmark   January 21, 2009 at 9:43PM
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bill_vincent

That makes it necessary to read the date of every thread before reading it. Am I the only one who finds this inconsiderate?

Sorry you had to go through "all that trouble". You just might be (the only one).

    Bookmark   January 22, 2009 at 7:39AM
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