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I prepared my tub walls for Swanstone but than someone decided we wanted to do tile instead. Seams are taped and spackeled and everything is flat and ready. Can i tile over green board? I remember taking an old bath apart and finding the tile had been glued up on greenboard with mastic instead of thinset and grouted... it had worked just fine. As an alternative i was thinking maybe just he 1/4" hardibacker over the greenboard? What should I do?
I tile over greenboard all the time. Just get a tub of c-tile glue and a trowel, and of course some kind of tile cutter, and go for it. A recent post suggested that greenboard is no longer code for certain states, but since it's already in place, I'd go for it. Just do a good job of grouting and caulking, and you should be good for twenty years or more. Don't forget to caulk around your fixtures as well.
Put up a vapor barrier, and then 1/4" cbu. Then tile. Grout is not waterproof. The holes you put in to secure the greenboard compromised the surface layer. Drywall compound (at least the premixed stuff in a bucket) will get soft again if it sees moisture. The gypsum in the greenboard is food for mold. If it gets wet, it is ruined, and it is almost certain to do it in a shower.
Greenboard NEVER was a great idea, and by national code (local may differ) is no longer approved for wet areas. A shower definately is wet.
Check out that website recommended...they'll set you straight and help - www.johnbridge.com.
Important note - I'm not a pro
Retired Defense Industry Engineer
If you don't want to tear down the greenboard you need to look into a product called Kerdi (See johnbridge.com forums). It can be applied in situations like this.
Otherwise your other options are to pull down the greenboard and put in a vapor barrier and CBU like has been suggested already.
I just spent the past few weeks tearing out our bathroom (house built in 89) that had greenboard in the tub and shower behind tile. It was mushy as heck and had started leaking. What a mess.
As stated earlier, I can completely understand why this stuff is no longer allowed in new construction in Tub and Shower areas.
I agree that using CBU and a vapor barrier is the better way to go, but I've seen shower areas that have remained in good shape for decades as long as the grouting and caulking have been well maintained. This is just another way of making things "idiot proof."
Last edited by Verdeboy; 09-13-2006 at 10:18 AM.
The most crucial information is missing, Jim.
If shower water is going to get on the tiles, skip NO steps; you'll need the vapor barrier. And leave a space at the bottom of the 1/4" Hardibacker so water on the tub itself doesn't have any contact point to it. There is always some way for moisture to get behind tub caulk, and Hardiboard does let moisture inside it, and this will wick...
If this is a tub-only, you have a few options. One is to do with a less-best option.
Tile and grout are not waterproof. Moisture goes through grout.
I keep hearing that tile and grout and caulking are not waterproof. If that's the case, then the tile adhesive would continuously get wet and there would be tiles popping out all over the place, regardless of whether you are using CBU or greenboard.
My experience, especially in the area of multi-unit housing, is that the only time I have to replace tiles and fix damaged greenboard is when grouting and caulking are missing or had not been done properly, and the tenant waits until several tiles have fallen out before calling in the maint. request.
This is a case where a technique was used for many years....sometimes there were never any problems, ,,,more ofen than not things were not A-OK under the tile, and that may never have manifested any problems until it was torn down..
We no know that there are drawbacks to putting tile on greenboard in a shower. There is potential for problems ( mold, etc) AND there are better ways to do it . so why would you not take advantage of the best modern material?
I actually agree with you, Jimbo. If I was starting from scratch, I would take the "modern" approach. But the thread starter already has fresh greenboard in place and is ready to go. I think, if he does a good job grouting and caulking, he can rest easy that it will hold for many many years.
I'm with jimbo.
Green boards AKA is MR board (moisture resistant). It is not and never was water proof.
If jhetzig doesn't want to change the board and the MR board is not resting directly on the tub, If the tile & grouting job is done right, If the grout is sealed & caulked & maintained it should give many years of service
for a few $$$ and 1/2 a days work the job could be far better by installing CB or similar and then never having the worry of a failure or mold growth due to water penetration.
If the walls are taped, seamed, flat, etc., I would put Kerdi over the greenboard. Not sure how the wall-tub interface looks, but do all you can to keep water from wicking up behind the Kerdi. Color-matched caulk is commonly used, I think.
more missing information: did you put your greenboard inside or only butting up to the tub flange? This is important.
I've done a few jobs using greenboard. They were usually at the request of the owner, or required by a condo to replace what was originally there (usually a double layer of 5/8" gb for sound installation and fire code). In those cases I've applied a double coat of Red Guard for a water proofing layer before installing the tile and epoxy grout for it's exceptional water resistance, long life, and very low maintenance.