Regarding the ceiling of a shower encluse: what topcoat should be added over cement board to create a non-tiled ceiling that will eventually be painted ? Thinset ? If so, what should be added for workability, water proofing etc..? Shower is simply a drop-down head without all the jets etc.. Contact with water will be minimal.
Thanks.
GR
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Replies
Tape the corners and skimcoat the cement board with All Purpose joint compound, sand smooth, prime with an alkyd/ oil primer and finish with 2 coats Benjamin Moore Aqua Pearl in any color you wish.
Done.
Frankie
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What Frankie said -- that's good advice.
Or, you could rip out the cement board and put up drywall (but NOT the green stuff) -- then tape and mud, primer and paint.
YesMaam,
You say no green board? Why so? I thought it was moisture resistant, better suited to this app.
Green board is more moisture resistant, but has less strength than ordinary drywall, so it tends to sag when used on a ceiling.BruceT
I wasn't aware that green board is more apt to sag, thanks for the info. I just did a soffit over a shower stall, but fortunately I put in additional support to make the fan easier to install . I should be ok, but I will keep that in mind for future plans.
Greenboard...MR drywall, is perfectly acceptable, and recomended for bathroom walls and ceilings that will not see direct water contact.
Standard 16" OC framing is also adequate support.
I do recomend that ceilings....any drywall ceilings....are double screwed however.
J. D. Reynolds
Home Improvements
Most who have used it agree -- and there's lots of info available -- the stuff turns to mush just as quickly as the regular drywall when it gets wet.Politics is the antithesis of problem solving.
I agree. With the advent of fiberglass faced board like DensShield and DensArmor, I see no reason to even consider green board anymore.
If you go with joint compound, use a hot setting (curing) one, that won't react with water as much after it cures. But nothing wrong with the thinset, if you can smooth it out enough.
But be sure to use an oil based primer. That is critical.
use a hot setting (curing) one
You mean like a 20 minute mix?
.
Edited 3/31/2009 12:30 am ET by rez
It could be 20, 45, 90... whichever gives you the working time you need. For that application I would use the original Durobond 90, in the brown bag. The easy sand is easier to sand (of course), but doesn't stand up to moisture like the origina, much harder stuff. Use 80 grit to sand it smooth, then 100 or 120 to take out the scratches.
I would use 2 coats of Zinsser BIN primer for that application, as it's shellac based will withstand the moisture real well. Use a fine sponge sander between coats to take out any bumps or buggers. Then a good quality satin, pearl, eggshell, semi-gloss or high gloss (anything but flat, matter of preference) latex paint with anti-mildew additive added. Paint store should carry something along that line.
Latex is more flexible than oil based paints, so less likely to develop microscopic cracks at inside corners. You can't see them but moisture surely will find them.
Make sure that shower gets plenty of ventilation, as the anti-mildew additive can only do so much.
~ Ted W ~
Tool Auctions - MyToolbox.netSee my work - TedsCarpentry.com
Edited 3/31/2009 4:08 am by Ted W.
This thread is rather timely as I've been wondering how to work the 20inch high box area above a 48"wide Sterling plastic shower alcove bumpout into an adjoining room in a bath remodel.
Entry from the pre-existing low ceiling original bathroom.
At first considered placing a vent fan in the enclosure but complictions were approaching rocket science so the fan in now placed instead about 5 foot away.
Used fiberrock on the sides of the box and am thinking of furring out the ceiling and using a cement board product over the wallpapered plaster on the ceiling of the alcove, then tape and paint.
I normally use Zinnser's bath/kitchen antimold paint as it has always proved itself a quality product but you are saying I should still primer with the shellac based primer first?
Thanks
.
Definately, you should prime first. Zinsser's makes some top qualiyt products, but paint is still paint, and not primer. Primer is formulated for bonding and sealing, while paint is formulated for coverage and, in this case, mold control.~ Ted W ~
Tool Auctions - MyToolbox.netSee my work - TedsCarpentry.com
Over drywall, I have had luck with fiberglass tape and hot mud followed by 1 or 2 coats of Gardz (Zinser product / waterborne penetrating sealer) and two coats of self-priming eggshell bathroom paint. That would probably work fine over cement board. As others have said, some kind of penetrating sealer is probably the key element.
Hot mud works well for what you are doing, and it is smoother than thinset because it has no sand, plus it can be sanded if needed. Thinset is very difficult to sand and tends to tear when sanded green.
Have you ever tried to trowel thinset smooth? It ain't easy. I'd go with the suggestion to use stucco base with a smooth topcoat. Durabond is OK, but also hard to trowel really smooth without sanding. I'd use a plaster topcoat myself, painted with a good mildew-resistant paint made for damp locations. (Well, I'd actually use tile, but you already ruled that out. Or I'd use a waterproof gypsum product like DensArmor or DensShield instead of the cement board.)
Mike Hennessy
Pittsburgh, PA