I’ve ripped out the bathroom and am rebuilding. The shower is enclosed in concrete backer board with tile. Tile runs to the ceiling. I will need to put a veneer coat over the ceiling concrete board both because of needing a smooth finish, but also to compensate for a slope of about 1/8″. What would you recommend for finish coat material?
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ok didn't quite understand your post.......
Are you building a new shower? Has old concrete board on the ceiling?
There is an 1/8 slope on the ceiling?
Usually on a floor, you can skim coat with thinset to level things out, but only to a thickness of 1/4 inch. Anything thicker requires Self Leveling compound.
So I would think you could just use thinset, but please explain the situation better.
It's a renovation with all new concrete board. I need to finish coat the concrete board on the ceiling (it's not going to be tiled) and am wondering what is the best material to use (ie, thin-set, drywall mud, etc...). I would try thin-set, but it doesn't look like it'll be very smooth.
I guess mentioning the ceiling slope is abit confusing. I realize now how it sounded and so disregard. I mentioned it so that the reader would know the thinckness of the finish has to be at least one eighth inch.
Thanks
My taper uses ap-light by Beadex over a large variety of boards --green, concrete ,hardy to name a few. On my high rise jobs where concrete is the finished ceiling material they use ap-lite aswell.
Remember it's the paint that's sealing the surface not the mud.
Ok OK I understand what you are saying now. No the thinset or SLC is if you are going to tile. You couldn't probably skim coat it with drywall mud....
I don't know anything about Ap/light that plumbbill is talking about, but it sounds interesting.
Why didn't you just put greenboard on the ceiling?
When in doubt, get a bigger hammer!
ap-lite = all purpose light weight - beadex is the brand basic taping mud.
I agree why not use green board. Since there is no tile going on it.
Also maybe it's just me but I don't like concrete backer. I use hardy backer & some really fun stuff called denseshield for tile applications.
Denseshield is 5/8" fiberglass reinforced sheetrock with a gray vinyl type coating on one side. Can you say itchy itchy itchy
green board isn't recommended for ceiling applications.
Jeff
Buck Construction
Artistry In Carpentry
Pittsburgh Pa
I have heard that about greenboard.
I am currently doing an indoor swimming pool for a hotel. They are using 5/8" greenboard on the ceiling about 3000 square feet I'll have to ask the guys about the properties of the product.
Assuming I can find one that speaks english
Thanks for the info Plumbbill----
Jeff: Got some info on that? I have heard rumors of that, but we have always used it in bathroom ceilings. Don't think it weighs any more than standard rock, and it comes in 5/8 too.
If it were my Baño then I'd be taking that CBU down and putting in some rock. I have my doubts as too how well mud stick to the stuff.
When in doubt, get a bigger hammer!
Custombuilt,Setting-type mud, like the USG Easysand you can buy at the orange Borg, sticks very well to Durock, and withstands high humidity and incidental wetting a lot better than premixed muds. You can get it smooth like glass without much trouble. And the great thing about the Durock on the ceiling is that water won't ever bring it down. Having said that, I will add that in an open shower stall I would just use regular 5/8" drywall on the ceiling if it was getting paint.Bill
check the manufacturers site and compare their minimum framing OC to what ceilings are usually framed with.
and even at that minimum ... the stuff sags over time in high moisture areas.
Jeff Buck Construction
Artistry In Carpentry
Pittsburgh Pa
Thanks for all the great feedback. I didn't use greenboard because I don't think it's as good around moisture areas as concrete board. I swore after rebuilding the shower in my last house that I wouldn't use it. I wish I had known about the 5/8" denseshield when I started. That would have made life alot easier. Thanks again for the feedback.
Richard
thanks for the inf. I'll have to try out the setting compound.
Yeah plumb-- I've had a couple encouters with denshield........thats can be some nasty stuff for poor fool installing it.
When in doubt, get a bigger hammer!
We had an entire shower built out of mortar that was painted. It lasted probably 70 years or so. So I would think that you could coat the mortar board with a smooth coat of mortar and paint it with masonary paint, that is if you are really concerned about moisture. But I would think that any setting type mud that is rated to adhere to CBU would also work.FYI, if you work with DensShield and want a painted finish, get DensGlass for the paint area. DensShield has a texture to help the thinset adhere, and where it gets taped it ends up with a smoother texture than the rest of the board. I have a vanity light that shines right down the board. I can see every imperfection, tape joint, and tape edge on the wall.
Greenboard is fine for the ceiling, but it is heavier, so 16 on center won't cut it--you'll have to use blocking.Then two coats of a really good sealer and an acrylic paint that resists moisture.Or F'it--just tile it. I mean why not?Regards, Scooter"I may be drunk, but you're crazy, and I'll be sober tomorrow." WC Fields, "Its a Gift" 1934