Replies

1. 
   Mongo | Mar 25, 2007 04:10am | #1

   I think differently.

   I don't worry about a Kerdi shower leaking.

   I don't use drywall because on an exterior wall, which most baths are on, I don't want the drywall between the vapor barrier (kerdi) and the exterior shell of the house.

   I don't want to use Kerdi over the drywall and visqueen behind it because then I'd have drywall sammiched between two vapor barriers.

   More later. Gotta go watch the Husky girls (no pun intended) beat up on some upstart team from NC.

1. 
   andybuildz | Mar 25, 2007 04:38am | #2

   Well the last two showers I did were on both on interior walls...how bout' those? Would you still use CBU then? Both on the second floor too.

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

1. 
   Mongo | Mar 26, 2007 09:53am | #25

   I think the more you do Kerdi, the faster you'll get with it.The irony is that the more complicated the shower...angles, niches, fancy curved seat and/or benches, etc, etc...the more Kerdi works in terms of it being able to better waterproof the shower.And I mean that in terms of it being a better physical barrier to deep water penetration, as well as being better in terms of installer confidence and beign able to walk away from the job and knowing that long-term, it's a "worry free" installation.The negative? Detailed showers can take longer to Kerdi. But in the end they are better. Better for the customer and better for the installer.You used a Kerdi pan in that shower, that right there saved you several hours of deck mud preslope/membrane/deck mud top layer. Materials vs labor on that one? Plus no seaming or folding the thick membranes, not having to notch out studs for the membrane folding up the sidewalls and corners? Oh, that's just priceless!Walls? Yeah, the Kerdi takes longer to hang than it takes to hang visqueen, but you don't have to tape/mud the CB seams with Kerdi. You can, but you don't have to. If tiling over CB, you have to tape and mud the seams. A little material vs labor there as well.Niches? You can do a preformed, or you can Kerdi a custom niche. A custom niche will certainly cost more, there's more labor involved. But in materials, a site-framed and Kerdi'd niche is less expensive than a preformed one.I dunno, bro.I went through a little bit of a quid pro quo on that Kerdi pic thread I did a few weeks ago. What's better on the floors, the walls, etc. It really depends on how well you work.To me, Kerdi sells itself, especially if anyone has had water problesm in the past. With mold remediation these days, tighter houses, etc, THAT sells Kerdi too.Me? I'll hang a sheet of CB any day before hanging a sheet of drywall. You know, it's funny, because about 16-17 months ago when we were emailing for a bit, Ole Johnny Bridge was howling at me that I wasn't using drywall. Has he really quit and gone to CB? He was always hardcore drywall behind Kerdi.I'm not the least bit worried about a Kerdi shower that I do leaking.From the building science perspective, I do have concerns, however unfounded they may be, of an exterior wall with the vapor barrier (Kerdi) on the interior side of the drywall.But that's just me.Cement board? I'll keep hanging it. I'd think a homeowner would understand that you're trying to give them a worry-free shower.I also think that as you become more experienced, you'll go faster, and you'll discover that the extra you pay for Kerdi material will be offset by you being able to actually work faster AND give the customer a better installation.Mongo

1. 
   Gene_Davis | Mar 27, 2007 04:51pm | #27

   Mongo, my little teenie market, in far upstate NY's Adirondack region, has gone almost 100 percent Schluter.  Maybe it's because Schluter's North America HQ and distribution center is just up the road in Plattsburgh.

   Here, you can buy Kerdi and Ditra by the foot, off of big rolls, at the lumberyards and hardware stores.  And every tile setter I know uses it.

   Since everybody is using it, has for a while, and is interacting with others, swapping technique stories, etc., most all the work I have watched go on happens pretty fast.  I think we are all well beyond the learning curve.

   Your assessments of cost and value are spot on!

1. 
   Mongo | Mar 28, 2007 12:18am | #29

   I'd love to see it sold like that around here. I buy Ditra and Kerdi in 3-roll packs. About $1K per, but they do last a while.Has Schluter yet stepped up to sponsor the Syracuse University sports teams? Can't wait to see the Orangemen really go "orange."Perspiration will just roll right off their uniforms.Practicing in the rain? No worries!

2. 
   mike585 | Mar 25, 2007 04:42am | #3

   I'll give you a non-pro answer:  I've seen the Kerdi system and I've seen the results of half-azzed leaking work. I'd pay the extra grand for the peace of mind provided by the Kerdi. The difference between me and the average homeowner is that I've educated myself on the subject (mostly here).  So, it seems to me that the key is to educate the customer so he/she understands what they are getting for the extra money.

   Namaskar

   P.S. I'm building a flagstone or blustone patio in the back yard this summer and I'd like to pick your brain a bit. More to follow if you are willing.

    

   "With every mistake we must surely be learning"
1. 
   andybuildz | Mar 25, 2007 05:00am | #5

   P.S. I'm building a flagstone or blustone patio in the back yard this summer and I'd like to pick your brain a bit. More to follow if you are willing.<<
   No problem!

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

3. 
   inperfectionist | Mar 25, 2007 04:51am | #4

   I talk to a lot of bath and shower folks in my area, what they are doing is using durock on the walls, deck mud base, kerdi drain, and kerdi on the floor and 12 to 18 inches up the walls. They kerdi the niches also.

   I tend to think this is not a bad system. There is no way I would build a shower out of drywall. The kerdi drain is nice,,,,, not cheap,,,,, but slick.

   I figure the mold issues are w the floor,,,, not the walls.

   Harry

    

1. 
   BryanKlakamp | Mar 25, 2007 05:31am | #8

   Harry,

   There could be a major flaw in using Kerdi the way you describe.

   If the Kerdi is on top of the Durock, then moisture will go behind the Kerdi, effectively defeating the purpose of using the Kerdi.

   Now, if you put the Kerdi on top of the deck mud base AND behind the Durock, with the vapor barrier behind the Durock overlapping the Kerdi, it would work. But, you are still defeating the purpose of the Kerdi. Kerdi is designed to keep moisture out of the backer, period.

   My thought is, either use the Kerdi the way it is designed, OR, don't use it at all.

   Waste of money to use it improperly.

   Of course, you may do whatever you wish.

   My 2 cents.

   Bryan"Objects in mirror appear closer than they are."

   Klakamp Construction, Findlay, Ohio

1. 
   jrnbj | Mar 28, 2007 05:43pm | #41

   Even though the concept of "rated assembly" applies here, it's still OK IMHO to mix & match...if the drain/membrane is a lot better than traditional, why not....

1. 
   BryanKlakamp | Mar 29, 2007 01:30am | #44

   The main point of my reply was - Do not lap the Kerdi on top of the Durock.

   Moisture will eventually get behind the Kerdi, and again, you will have a cesspool in the mud base and leaking through the floor below.

   If you want to mix products, that's up to you, but make sure that they are lapped properly.

   Bryan"Objects in mirror appear closer than they are."

   Klakamp Construction, Findlay, Ohio

4. 
   EricPaulson | Mar 25, 2007 05:09am | #6

   Andy,

   No time now, I'll get to you tomorrow with some good info I got from someone doing a lot of them.

   [email protected]

    

    

    

    

1. 
   andybuildz | Mar 25, 2007 05:29am | #7

   OK thanks...can't imagine a better answer than what David gave and also that CBU's are "code" in a lot of areas someone else told me but I don't care about that...I wanted a more practical/scientific answer.

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

1. 
   katiewa | Mar 27, 2007 09:52am | #26

   I wanted a more practical/scientific answer.

   Has to do with risk analysis, single-point failures, and redundant systems.

   Kerdi appears to be a good system; however, things can go wrong with any system/product.  On some things this is not a big deal--if the problem is easily detected, relatively easy to fix, and the damage caused by the problem is low--a single-point failure is not an issue.  On a shower, it is.  Small leaks are difficult to detect, yet can cause significant damage.  And the fix is painful and costly.  On a shower you want redundant water protection components.

   Kathleen

   (Hopefully this information, learned from my engineer husband, will not put us into the "over-specifier" category of potential clients and adversely impact our chances of finding a good builder :-))

5. 
   davidmeiland | Mar 25, 2007 08:48am | #9

   My customer at the moment decided to go with Kerdi after we talked about the two or three possible ways to do it. He checked out the Schluter site. He checked out my Michael Byrne book with the traditional details. We agreed that keeping moisture out of the mortar and CBU seemed like a killer idea, and that was it. He's an engineer so he's able to "get" the whole thing.

   For a 3x4 shower with three walls tiled to 6' and a mortar preslope floor I've got ~$400 worth of Kerdi stuff. I bought the 10" band and used it without cutting, instead of the 5", and I bought a bunch of extra corners that I really didn't need, plus some of the roll is left over, so the actual amount spent on this job is more like $350.

   Time to install the Kerdi was ~8 hours but I really took my time and made a geeky science project out of the whole thing. Next time will be faster.

   I will say that actually installing the membrane is tedious. I ended up with a headbanger station on the radio to get me thru the last few hours.

1. 
   andybuildz | Mar 25, 2007 09:23am | #10

   david...the answer you gave was the best answer of all of em'!! I rephrased it or shortened it to..."cement to cement to kerdi to cement to tile". Says it all if you ask me!

   I agree about the time frame and I posted over at JB's that I felt a typical Kerdi job was about another grand $500 labor $500 materials..on 4x4 approx size.

   Here's some pic of my first Kerdi job start to finish w/the least expensive tile I could find. Tumbled marble from HD at about $5 a sq ft...and a gazillion cuts..ugh.

   edir: whooppsss theres one in there my daughter took of me on the way home today in the van...lol

   I still have to grout btw...duh

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

   Edited 3/25/2007 2:27 am ET by andybuildz

2. 
   andybuildz | Mar 25, 2007 09:35am | #11

   another thing..on the preslope I cut a 4x4 to 39" x 48" with no problem at all with the pitch. And no way can you even see it.

   It is definatly time consuming but like you said...the next time should go faster now that I've done it once.

   MAkes you wonder about Schluter though...we know the positives but to say you can hang DW on a ceiling and then kerdi on that and then BIGAZZ tiles if wanted on that...on a ceiling??? I don't think I could sleep at night but maybe they know something we don't!

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

3. 
   andybuildz | Mar 25, 2007 09:50am | #12

   ahhhh WTF...I'll throw these in too...lol...I just finished this bathroom while I was waiting for my wet saw blade to arrive from Tool King for the Kerdi shower (2wks for the blade to arrive) ...

   just need to grout that wavey thing I made and its 100%.

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

1. 
   jimblodgett | Mar 25, 2007 11:21pm | #20

   Looks great, Andy. Inspiring. 

   What are you going to do on the outside wall?

    Remodeling contractor who once visited the Glass City.

1. 
   andybuildz | Mar 26, 2007 04:07am | #21

   What are you going to do on the outside wall?>>
   Thanks James..I donno...not what I want to. Its already taken too long considering we'll be selling. I bought this awesome set of raised panel cutters from Infinity Tools..I was gonna do a shirtload of raied panelsfrom MDF around the whole room w/bookcases etc etc...but its not making sense to do that anymore. Only so much time left and I "really" do have to go back to work for customers again...ugh...so...sheetrock paint and be done with it. Its already more than I was originally gonna do. It was just going to stay an empty attic space but we figured making this a 3 full baths and 1 half bath house would add a lot more value...Actually this whole bonus room is going to be my favorite room in the house...almost makes me wanna stay....almost.
   Might see you in August...depends how it goes for all of us..may end up being during the fest so you wouldn't be around anyway...we shall see.
   andy

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

1. 
   jimblodgett | Mar 26, 2007 05:35am | #23

   We're not going to the Fest this year - our youngest is getting married late July - so if you do happen to get out this way we'd love to have you for as long as you'd like to stay.  For a cup of coffee, a meal, overnight, or for a couple weeks.  Whatever you're comfortable with.  We'll leave the light on for ya.Remodeling contractor who once visited the Glass City.

2. 
   andybuildz | Mar 26, 2007 06:19am | #24

   Thanks James...I'll pass that along to Katrina...youngest married...mine's havin'a baby...geezzz...we old r sumpin'????

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

3. 
   mrfixitusa | Mar 27, 2007 09:34pm | #28

   The tile looks great !Is your wife a Realtor?If so, you guys make a powerful team.Especially if she can pocket 100% of the sales fee when you guys sell them?^^^^^^

    

   a Smith & Wesson beats four Aces

4. 
   andybuildz | Mar 28, 2007 05:23am | #35

   Well no one pockets 100% of anything plus the market has to be lined up with the stars when we sell : )
   Everythings a risk...some things more than others. This of course is more of a calculated risk but a risk none the less.
   Makes life interesting though : )

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

5. 
   mrfixitusa | Mar 28, 2007 05:40am | #36

   Here in Kansas the sales commission is 6 percent.The listing agent gets three percent and the selling agent gets 3 percent.(when the home gets listed in the MLS system).I will be selling the house I live in at some point and I would like to sell the house myself and get both sides of the commission.This would mean keeping it out of the MLS system, which is risky because I will be the only one showing the house.I would just have a For Sale By Owner sign in the yard.I think I'll probably start out FSBO and if I'm not getting anywhere in a month or two I'll put it in the MLS system.Good luck!^^^^^^

    

   a Smith & Wesson beats four Aces

6. 
   jesse | Mar 28, 2007 05:46am | #37

   Well, no. Just because an agent takes a 6% listing doesn't mean they have to offer 3% to other agents. They can offer 2.5%, the rationale being that they are spending a bunch of money on marketing.Anyways, you might have better luck with a FSBO if you offer 2.5-3% to agents who bring a buyer.

7. 
   davidmeiland | Mar 28, 2007 06:39am | #38

   I agree. We sold a house without an agent but we offered 3% to the buyer's agent. Unless you do that they won't bring anyone. I suppose if you're in a smoking hot market you might be able to sell directly without an agent on either side, but in most cases the agents control the buyers.

   Uh oh... the hijack alarm is going off.

8. 
   jayzog | Mar 28, 2007 01:18pm | #39

   I wish I had put a FSBO sign out.

   Just sold a spec house, paid the RE agent 5%, they did a good job, good number and quickly.

   The kicker is the buyers live 2 houses down the street! ARggg- pissed away 5%.

6. 
   JeffBuck | Mar 25, 2007 09:59am | #13

   I'll preface this by saying I haven't yet used Kerdi.

   but ... from my understanding of it ... seems to be the better choice in a nonstandard shower layout.

   I've had some showers in the past I think would have been ideal candidates.

   all since I learned about Kerdi have been more or less straight forward.

    

   square or rectangle ... with limited nooks. shelves, benches.

   Those ... I fully intend to do the "standard way". No need to step up to Kerdi, as I haven't had a leak yet ... so I'm not worried about leaks.

   and when I do get the next odd space shower ... or one with a ton of nooks and cranies ... I'll give Kerdi a shot. And I plan on using drywall, just as they recommend. As to me ... that's the whole point of the product.

   same with Ditra. Great product ... but I limit my application of it. No sense adding to the cost just because I can.

   there are cases when the only underlay I will use is Ditra.

   I'll use it if it definitely makes for a better job, or if it makes my life easier.

    

   I think of the Kerdi the same way. And in those limited situations, it's not really "adding" to the cost of the job ... it's just a specialized job is gonna naturally cost more. And the specialized materials are part of the process. So the customer will pay ... if I'm to do the job ... as that's the only "option" I will present.

    

   Jeff

       Buck Construction

    Artistry In Carpentry

        Pittsburgh Pa

1. 
   andybuildz | Mar 25, 2007 06:55pm | #15

   >>>No need to step up to Kerdi, as I haven't had a leak yet<<<<Jeff...The reason I used it besides wanting to learn how to install it was because a real big complaint people have down the line about their showers is mildew which is whats made Tilex such a popular product. It removes mildew. Mildew is a hassle for people as well as unhealthy. The water/moisture sits behind the tile especially when the grout wears over the years. The moisture sits on/in the CBU cuz as you know a CBU is cement and cement holds water and then produces mildew. This is a huge selling point in my eyes as to what Kerdi does. It keeps the moisture from going back past the tile....as well as preventing any leaks. I thought the same thing as you until I thought more about it. Thats a huge selling point. Look back at David's post too.>>>And I plan on using drywall, just as they recommend. As to me ... that's the whole point of the product.<<<

   You're gonna hate this but thats wrong! I started another thread somewhere else about this topic too...over at JLC and John Bridges forums too..and David had THE best answer I've heard to date.
   It DOES work on drywall but it should be used on CBU's (sorry) cuz thinset is a cement product not meant to be put on paper really (drywall)..you "can" and I "did" but I won't ever again. If there is a leak behind the drywall...say from a pinhole in a supply line...or where ever...the drywall will turn to mush behind the Kerdi. I'm also concerned about thinsetting real heavy tile to a ceiling and just the kerdi stuck to a paper backing holding it. May be unfounded but it does concern me.
   Also...drywall in shower/wet areas is not to "code" in a lot of places.
   doesn't matter though once you realize what I said above...its to keep moisture and mildew that forms out...as well as leaks from the inside of the shower.>>>I'll use it if it definitely makes for a better job, or if it makes my life easier.<<<It'll make your customer's live's easier and healthier...and it'll make you more money...well deserved.
   Be well
   andy..

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

1. 
   davidmeiland | Mar 25, 2007 07:14pm | #16

   Dude, how do you have time for all this work on your own place? You must have one of those high-powered wives who's raking in loot bigtime while you toil away on the house. Does she have a sister?

1. 
   andybuildz | Mar 25, 2007 08:08pm | #17

   yeh...she spends alot of time playing tennis...lol.You forget, Real Estate right now is pretty bad so no..she's FAR from raking it in.
   We live off of previous house sale profits. Her money has always been gravey.
   You forget...I work on my own houses then sell em'. Its one of the "big" perks. Unfortunatly or fortunatly depending on how you look at it my puter room is ten feet from where I'm currently working...ugh.
   Nice thing too about working on your own house to make money is your hours are your own...I can start at 4 A.M which I actually do a lot of the time..and quit for an hour or two if I want then start back up and work in the evenings....my time is my own...no one to answer to. I can't think of a better working money making enviorment and it took me almost thirty years to get to this point. It was always the plan from the get go. Course when I start a huge project like this I can't be this lax...wayyyyyyyyy too much to do but I'm wrapping this house up and selling it in less than a year and on to the next venture : )

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

2. 
   andybuildz | Mar 25, 2007 08:15pm | #18

   oh yeh...and I do still think about the San Juan islands over there..too bad theres no tennis for Katrina...really. I searched the web. Seems everywhere I'd love to move hasn't enough tennis for Katrina.
   I wish there wasn't "so much" tennis around here. More tennis places than Home Depots..lol.
   Then we looked in Northern Calif..and bid on land in Sebastopol before this house but our offer wasn't accepted..I look there currently on line and its more expensive than Long Island,,,ugh.
   Friggin' tennis.... Makes for such limitations...lol

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

1. 
   davidmeiland | Mar 25, 2007 11:11pm | #19

   OK, so she's not raking in dough, but she's a tennis goddess.... Katrina Cliffordsova... I still say, does she have a sister?!

   No tennis here, but there's a nifty little racquetball clique. Real estate is not selling either. No way I could move this shack for what I want to, right now. Maybe that's how we know it's time to buy another?

3. 
   andybuildz | Mar 26, 2007 04:10am | #22

   Sorry David...no sisters...good looking brothers though...interested? LOL
   Sure hope the RE market picks up in the next year is all I have to say!!!
   I'd hate to "have to" stay here and wait it out. KAtrina and I were even putting it up for sale this summer depending on how things look...Timings everything ain't it?

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

7. 
   Waters | Mar 25, 2007 06:46pm | #14

   To andybuildz et all:

   I've wondered if anyone has used kerdi or like to build custom tile tubs?  Like in the japanese style of deeper/shorter soaking tubs or whatnot?

    

8. 
   jayzog | Mar 28, 2007 01:37am | #30

   For the past couple of years I have been using Kerdi over cement board, but doing a conventional liner and mud pan. My tilesetter doesn't think the Kerdi is neccasary, but I make him do it anyway.

   Today he came back from the supply house and said on the next one how bout we

   use this stuff http://laticrete.com/Architects/Products/NewProducts/HydroBan/ProductInformation/tabid/426/Default.aspx

   You just roll-brush it on for a membrane, saving a lot of labor.

   Has anyone used it? Something simular?

    

1. 
   Mongo | Mar 28, 2007 02:53am | #31

   Never used it.Pluses: Sounds like a good product.Negatives: To roll it on cement board you first have to skim coat the cement board with thinset. Then you have to wait for the membrane to cure before you tile over it.Time delay? Cement board, then skim coat. Let cure overnight? Next day roll on the membrane. Let cure most of the day or overnight? Next day tile.Time is money!Still, sounds like a good product.One other thing...detailing the pan-to-wall intersection...how to "bridge" with the roll on membrane? You want some flex for house movement, that's my worry with roll-on or trowel on membranes. How well they maintain their integrity with movement.Most are anti-fracture, good for 1/8th inch or so. But that's why I like Kerdi. No worries.Mongo

1. 
   jayzog | Mar 28, 2007 03:39am | #32

   Some good points.

   You obviously read more on the link that I posted than I did.

   If the building moves what happens to Kerdi ? I havent read their specs carefully either.

   I have seen many times where the exterior walls are 3/8" above the floor,held by the plywood sheathing, because the floor joists have shrunk that much. Would the Kerdi tear? Delaminate from the base?

   That ? at the wall /floor intersection has always bothered me, I guess that is why I have stayed with a conventional liner.

   I have liked the Kerdi, and will continue to use it.. maybe the next one I'll even do the floor, but that will be at my house, the test zone.

    

    

1. 
   andybuildz | Mar 28, 2007 05:18am | #33

   My Kerdi job was sitting about two weeks with some drastic weather changes in the room due to the cold and then my bullet heater over and over(its still unheated) FWTW. Right before I tiled I filled the pan right up to the brim (5"ish) and left it most of the day with the drain plugged. Not one dropped leaked (the ceiling's open below). For whatever thats worth...Was worth a lot to me!
   I also did a bunch of test pieces. One where I wrapped a chunk of sheetrock with Kerdi in thinset, Dropped it in my cleaning water bucket for days...cut it open..dry as a bone. I did a test on Luan as well...not that you'd be kerdi'ing luan..but I did on the curve I made on my footstool and thats against luan's recommendations. Worked fine "as long as you rough up the luan with a 36 grit sandpaper" otherwise the thinset and kerdi won't hold as well I found..mostly due to the mill haze I think.

    

    

    

   http://WWW.CLIFFORDRENOVATIONS.COM                                   

    

2. 
   Mongo | Mar 28, 2007 05:20am | #34

   Nothing scientific, but I did a few test using different thinsets, dry set, lightly modified, heavily modified, etc......then tried to pull the Kerdi off the cement board.They all adhered pretty well, the worst that happened is the spun fleece delaminated from Kerdi's polyethylene core, but the poly itself was pretty tough to tear.So yeah, I feel confident Kerdi can handle a bit of joint movement.Depending on the particular structure, at some joints I also don't thinset the Kerdi to the substrate right at the joint. I'll still thinset the joint, but I'll use a strip of painters tape or something to keep the thinset from sticking to the Kerdi.Kerdi does make a product for that...I don't use it, so I'm unfamiliar with the name...but it's a strip like Kerdi Band that has a 1" or so strip down the center of it where there is no fleece.If you haven't yet done Kerdi over a drypack preslope, you'll like it. I posted some pics on the "Kerdi with Niche" thread over in the Photo Gallery. The floor starts on this post: http://forums.taunton.com/tp-breaktime/messages?msg=86714.22

1. 
   davidmeiland | Mar 28, 2007 05:40pm | #40

   >>I did a few test using different thinsets, dry set, lightly modified, heavily modified, etc...

   Did you notice any difference between the various recipes? I don't remember from your photo thread what you used for Kerdi-->CBU and for tile-->Kerdi.

2. 
   Mongo | Mar 28, 2007 07:53pm | #42

   Initially I did small patches, then looked at them late that day and then again the next day. Not much difference between the dry set and the lightly moidified, but the highly modified did take longer. There wasn't a substantial difference, as due to the small size of the patches air getting to the thinset wasn't really a problem.I then did larger squares of Kerdi samples, there the difference was more apparent. The dry set fully cured a little faster than the lightly modified (Versabond). The highly modified (Flexbond) was still not fully cured after a couple of days. The edges of the sample were cured, but it was still soft in the center of the sample.You probably know that modified thinsets require air to cure, and that's why Schluter originally mandated that dry set only be used. No air can get through the polyethelene, so the modified mixes may not get a proper cure. No proper cure means a lower strength bond.My "testing" was as unscientifically low-tech as you can get, and about as subjective (my opinion vs measured results) as you can get. My opinion.To me, the size of the tile could also be a factor. No air will pass through the thickness of a porcelain tile, so modified thinset sandwiched between air-blocking porcelain tile and air-blocking Kerdi may have difficulting reaching a timely cure. Picking extremes, large format porcelains would be more at risk than smaller mosaics for a couple of reasons:
   -Large format usually requires a slightly thicker bedding of thinset than small mosaics to ensure full coverage
   -smaller mosaic tiles would also allow more air to the thinset through the spaces between the mosaics.Again, unscientific.I have been told by others that natural stone will allow air through it better than porcelains.My conclusions? I wouldn't use a highly modified thinset with Kerdi. I think that you could use a lightly modified thinset on walls with no worries unless you're using large tiles. You might still be able to use it, but ?? who knows. If I were doing tile on a floor over Ditra, I'd just use dry set.To answer your question: On the preceeding shower, I use gray dryset between the cement board and the Kerdi. I used white Versabond between the Kerdi and the tile. Partly because I felt comfortable switching to Versabond, partly because I wanted white thinset behind the tiles and I couldn't get and white dry set.What did I learn? I'd feel comfortable using Versabond to thinset the Kerdi to the cement board. I bought the dry set ahead of time for this shower, so I already had the dry set on hand.If using something like DenSheild as a backer behind the Kerdi? Denshield's facing is a vapor barrier, so I'd only use dryset to adhere Kerdi to DenShield or something like DenShield.A while ago I talked to Schluter's tech department and pretty much asked them about the conclusions that I came to. Back then he said that he agreed that:
   -lightly modified thinsets were okay on shower walls and on shower floors where you only have 2-4-6" tiles max on the floors.
   -Non-shower tiled floors over Ditra? Use dryset. It's not that the modified won't cure between the tile and the Ditra, but that the cure time may be excessive, restricting how soon you can walk on the floor or grout it. It may seem cured around the edges of the tile, but the interior bond may still be soft. Walking on it could shift or flex the tile slightly, breaking the bond without you knowing it.Makes sense to me.He said that they plan on allowing wider use of modified thinsets in the future, but that they're wrestling with their legal department over it. Mongo

2. 
   joeh | Mar 29, 2007 12:09am | #43

   Looks like their old green product without the fabric, but on page 3 of the photos they are using the same fabric to cover seams and corners.

   Guess I'd try it, I'm in a Kerdi free zone here and I have used Laticrete before with no problems.

   Joe H