We’re prepping a shower for porcelain tile (for the first time) and are in the process of installing the Durock on the walls. We just noticed from the installation guide that the smooth side of the Durock is for mastic applications and the rough side is for thinset. Obviously, since it’s the shower we’re planning to use thinset. So, now we have much of it with the smooth side out, and some with the rough side out.
Will it be a problem to tile over the smooth side of the Durock with thinset? Will there be any additional problems because some of it is one way, and some the other?
Thanks for the help.
Replies
I would reinstal the backer, thinset will bond better with the rough side out.
It's not a problem.
If you have any doubt at all, thin set a couple of tiles to some scrap, wait a couple of days and try to get them off.
No worries, go ahead and set your tile. Make sure you realy comb on the thinset very well, back and forth in multiple directions, a small section at a time with the correct notched trowel.
Good luck.
edit
Make sure you put fibre tape (the special blue kind if you can get it) on all joints and corners. Do this first and let it set up before you try to install any tile.
Let me know if you need any more help and post some pics when you are done.
Eric
[email protected]
It's Never Too Late To Become What You Might Have Been
Edited 1/8/2006 7:33 pm ET by EricPaulson
Either side should be fine. If you want to make sure you get good adhesion, apply a thin skim coat of thinset to the board. Do it when you fiberglass tape the seams for in the durock water proof joints. This coat will give you plenty of "rough surface". If it were me, it would be a lot easier to do this than flip the board.
Note, the mud (thinset) does not stick because of the roughness of the surface. It is a chemical process called hydration that creates the bond - see: http://en.wikipedia.org/wiki/Concrete
Good luck.
Edited 1/8/2006 9:56 pm ET by TTF
I may sound like a stickler, but did you meant to say "waterproof joints"? None of the CBUs are waterproof. They are water impervious (unaffected).
I just didn't want your novice to be mislead.
Sorry - you are correct. They are not water proof, but water resistant. Shouldn't answer posts late at night...
Leave as is.....it will bond just fine.
J. D. Reynolds
Home Improvements
Like the others said, in you case it doesn't matter. If you were using mastic, you would want the smooth side showing because the mastic goes on in a much thinner later, and the roughness of the rough side would affect the adhesion.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Hope I can ask a question of my own, doing same thing. I was planning on mastic for a shower stall. Any thoughts on why thinset would be better? Does it depend on the weight of the tile being applied, in my case small ceramic, probably "subway" tiles 3x6".
Thanks
Kevin
It has nothing to do with the weight of the tile. Mastic deteriorates in the presence of water. People have a hard time understanding, but water will find its way through tile and grout ( even sealed ) and mastice which is organic will fail. Thinset is not hard to work with. It is superior. It will also get wet and water will penetrate it also, but it won't turn to goo.
Behind the CBU you should have a water impermeable barrier or use a product on the surface of your CBU called Kerdi ( plenty of references to this in the archives )
thanks max, i'll check the archives.
Hope I can ask a question of my own, doing same thing. I was planning on mastic for a shower stall. Any thoughts on why thinset would be better? Does it depend on the weight of the tile being applied, in my case small ceramic, probably "subway" tiles 3x6".
Take a look at this thread:
http://forums.taunton.com/tp-breaktime/messages?msg=63686.1.
It has some good information about thinset vs mastic. I'm a convert (I won't use mastic in a shower again). There are other threads also. You can use the search feature.
Basically, mastic is not waterproof, but will work if it never gets wet. That's hard to guarantee in a shower. Thinset is a cementitious material and like any cement, it's not affected by water.
I don't think the weight of the tiles is a factor.
-Don
Like I said in my reply I would install it the MFG states, but this is coming from a GC point of view. I had a house were my tile sub installed durock the other way and 2 months latter the tile started falling off. I called and had a field rep check it out and stated that thin set will bond better to the rough side witch is needed for a wall install. Rep also said if backer was the problem they could void warranty due to being installed incorrectly. Do as you wish, I am coming form a GC aspect and when their are problems I am the one liable for it.
Sounds to me as though the Durock rep was covering his tail. He found a technicality that got him off the hook. How tiles falling off a wall could be his problem in the first place is beyond me (Were the backer board failing in some manner would be a different story.)....but, he found his out.
I'm not suggesting that the Mfg. install procedures should be disregarded. In practice, rough side out when using thinset is proper.
I doubt that the scenario you described was the fault of the backer board. But you are wise to insist on following mfg. instructions.
J. D. Reynolds
Home Improvements
You are right, the backer was not the problem, but any time I have a product warranty issue I call the rep first so they can be their when we explor to see what the problem is. Had I known the backer was installed incorrectly I would have left them out of it. This was the 2nd job I used this tile sub for and a few jobs latter with problems I sent him packing.And you are right the rep found a loop hold he could use if it was a backer board failed, that's why I always have the install directions followed to the letter just in case.
that's why I always have the install directions followed to the letter just in case.
Very shmart man!
I love when subs try telling me their way is "better" than mfg. installation directions. Thats fine when it's thier tail on the line.
J. D. Reynolds
Home Improvements
Thanks to everyone for their input and advice. I would certainly have prefered that we install all of it with the rough side out (with no hands-on experience, my preference is to do it as 'by-the-book' as possible), but am glad to hear that we don't necessarily have to reinstall it all. This project is on weekends at my in-laws house (their basement bathroom), and everything always takes 10 times longer than we think it's going to. Particularly while trying to take care of a 2-year old at the same time. We'll definitely be following the advice y'all have given, and will do the skim coat of thinset when we do the joints.
I've heard of the Schluter Kerdi system (saw it on Bathroom Renovations or similar show), but it was kind of expensive, so we opted for the tar paper under the Durock. We actually put some plastic sheeting up first, then the tar paper, then screwed the Durock to the studs. Anyway, we did a preslope the best we could with the space we had (the plumber installed the drain kind of low in the cement subfloor and we had very little room to work with), then put our roofing felt and membrane over that. Next step after getting the lower courses of Durock up is pouring the shower pan. We're following instructions in a Taunton book on bathroom renovations, but we're still a bit mysified as to doing the curb/threshold part of the pan. If I recall, the author uses cement board on the curb rather than using mortar for it, and we can't quite figure out how to affix the cement board to the inside of the curb without putting any fasteners in that would puncture the membrane. Can we use the metal lath over the curb and use mortar for the inside, but still use cement board for the top and outside?
Anyway, thanks again for all the help. Given the effort (and expense) of doing this, I certainly want it to turn out well and last for a while! My in-laws' whole house needs work (they bought it as a fixer-upper 20 years ago and haven't fixed it up, not to mention that the previous homeowner was quite a 'handyman'), so this is our first major renovation project there. They deserve something in their house that isn't falling apart!
Kirsten
See if you can find the Taunton book "Setting Tile": by Michael Byrne. He has a chapter devoted to showers, and clearly shows how toi use wire lath to form the curb.
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
When installing tiles a firm scratch coat on both surfaces ensures good adherance.
Hey Kirs10:
There is some good advice here on setting your tile. A few points on how we prep and set tile: First we always use cement backer board screwed directly to the studs. Over that we use the Schlueter Kerdi system(the orange fabric), in fact most of the time we use their pre-formed foam tile base with Kerdi cloth over everything. We run the cloth up to a 6 ft height. When combing on the thinset DO NOT create a swirl pattern in the thinset. ALWAYS comb the thinset in straight lines and make sure to nest the tiles in completely for 100% transfer, thereby eliminating any air pockets behind the tile that always result from setting tile in thinset which has a swirl pattern to it. Air pockets behind tile in a shower = mold, mildew, and who knows what else. We comb our thinset this way no matter what the tile installation - walls, floors, countertops.
A good way to practice - all of my field guys go through this - is to comb thinset on to a 4'x4' piece of plywood, and set 12" square pieces of glass into the mud, just as if they were real tiles. This will show if the process is being performed correctly and if you are gettting 100% transfer. We always back butter our tiles if they are larger than 10x10, for better adhesion.
Good luck
Interesting post Sully.
Makes a lot of sense to me too.
There is a post here someplace with someone asking questions about detailing membrane for what I think he is describing as a step down shower.
Are you able to buy the Schluter products local?
Please stick around, it's always nice to get fresh ideas.
Eric[email protected]
It's Never Too Late To Become What You Might Have Been
We are in St Louis MO so there is no shortage of supply houses to purchase from. We have 3 favorite tile suppliers we purchase from and 2 of them carry the Schlueter products.
One of the benefits of living in a populated area is the access to extensive training on various products and techniques. We attend training seminars on a regular basis - about ten a year - on all phases of construction. After 28 years of doing construction I still am able to learn something every time. At a tile seminar 2 years ago I was kindly chastised when I suggested swirling the thinset to set tile. The instructors explanation and demonstration of combing it in straight lines made perfect sense. You really can teach an old dog new tricks.
Thanks
I bought the schluter shower kit at Home Depot. They have a list of suppliers on their website, Home Depot was the cheapest and had the 30x60 size in stock, that the others didn't. They have the Kerdi there as well, by the foot. The kit comes with an installation video, and the video is also on their website. I installed my durock smooth side out, so hopefully it's okay with the kerdi system, you'd think it would be easier to apply the membrane to a smooth surface. The instuctrions just say to install the substrate to manufacturers specs.