Proper Installation of Kerdi Band?

Discussion in 'Shower & Bathtub Forum & Blog' started by Jeff C, Dec 23, 2013.

  1. Jeff C

    Jeff C New Member

    Messages:
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    Location:
    NJ, USA
    First off, I want to say,"Hello!". My name's Jeff C. and I'm new to these forums (albeit I've surfed them many times in the past several years). The reason I'm posting, is because I have huge dilemma, and you're my last hope (pretty much). I'm more than 3/4 through with a reno of our Master bath, and have reached an impasse as far as how to finish the gap between the concrete backer board (HardiBacker 500), and the tub edge. Here's the layout of the job:
    1. Tub is going into a 3 wall alcove with one of the three walls being an exterior wall w/a window in it
    2. Tub (a Kohler Hourglass 1219-L; free standing with integral tile-flange, and no apron as I'm framing a knee-wall and tiling it instead)
    3. .6 mil plastic sheeting over the studs (in hindsight, if I had found these forums earlier in the project, I would have just used RedGard or a Noble product, and I probably wouldn't need to ask for further guidance, but que sera, sera)
    4. As mentioned above, HardiBacker 500 on walls installed with the recommended screws (1st course is already up, and taped)

    Ok, so the install instructions do say to bring the CBU over the flange, but due to that one window on the exterior wall (not to mention a huge pita), shimming the studs out any more than I did (1/4") was just not feasible. Sooooo, I'm trying to make the best of the current situation by "adapting to my environment". Which brings me to a couple of questions:
    Q1: I know that waterproofing the seam between the CBU and the tub is a crucial one to get absolutely correct, so I plan on using Kerdi-Band, with Kerdi-Seal, to tackle this seam. But, I'm not sure how I should install the Kerdi-Band. The install instructions say to bed it in thin-set on the outside of the CBU, but I'm wondering if this will have a detrimental effect due to the 6mil plastic already installed over the studs, under the CBU (the whole "two waterproof layers trapping moisture" thing) The other alternative is to install the Kerdi-Band behind the CBU, but if that's the proper installation method (in my case), should it go on top of the 6mil plastic, or underneath it?
    Q2: I've seen it mentioned, by one knowledgeable person on these forums, that "the tub should be filled with water before pinning it to the studs". Is that correct? (as I was under the impression that it should be filled with water/weighted down, prior to caulking, but have never heard filling it before screwing/nailing it to the studs.) If it's recommended that it should be filled/weighted down prior to nailing it to the studs, how is that accomplished? I mean, how would I prevent a 500+ lb tub from shifting around, off the shims, and/or potentially ruining the entire drain structure or whatever?
    This reno is going on over 5 years now (my wife has been very understanding, but her patience has run out) and has hit a serious snag (because I'm scared as hell at messing it up at this point). ANY help/opinions/intruction will be soooooo appreciated that I may name a grandson after the person that guides me in the right direction ... Thank you, thank you, thank you, in advance !!! .... Jeff C.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    If you are going to use a surface waterproofing, then I suppose you could use the Kerdiband there, otherwise, I do not think I'd use it at all. With the plastic behind, and Kerdiband, any moisture that may penetrate the cbu would be trapped. The beauty of a surface membrane is nothing on the entire wall behind it gets wet. In what you have, the cbu can wick some moisture, but the plastic film behind it protects the studs. The tiling flange (if your tub is level!) keeps water from sloshing into the walls from the rim, and the tile prevent major moisture from getting to the cbu in the first place, so it only has to dry a little, since it never gets very wet in the first place.

    Now, if you wanted to use the Kerdi system and waterproof the walls, Schluter has some diagrams on their website that describe how to do that. You'd use some KerdiFix to seal the Kerdiband at the tub wall junction, and thinset on the Kerdi/Kerdiband to waterproof the seams going up the wall.

    There are probably some hybrid systems you could use, but you wouldn't have a warranty. Lots of tub/showers work and last with the plastic sheet draped over the tiling flange, tile and caulk at the tub/wall junction. As said, though, if the tub isn't level, and water pools or flows back rather than into the tub, those can be problematic.
  3. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Sorry folks. I removed much of this discussion since it refrenced Kerdi and I have quit using and talking about Schluter's products.


    JW - "When it's perfect. It's Good Enough."

    www.No-Curb.com - my blog site on Barrier Free, No Curb, No Dam and Hobless Showers
    (604) 506-6792 jfrwhipple@gmail.com
    Last edited: Dec 13, 2014
  4. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Post(s) deleted by John Whipple
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  5. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Full topical water poofing approach

    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  6. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Kerdi Band to back side of board.

    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    FWIW, my definition of hybrid install is any set of products not installed in accordance with the local distributor's instructions...many of the products are designed as a system, and have unknown and possibly (not definitely) unknown characteristics and performance when not installed as designed. John likes to do his work his way, which in my definition (and the manufacturer's) is a hybrid system.
  8. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
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    Location:
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    The point being...if a manufacturer has a system that works, it is best to use it, and install it properly. Mixing systems is not necessarily going to improve the end result, and may lead to failures that are unanticipated. The manufacturers design and test things, and have a vested interest in preventing failures but those only apply if they are used as designed. You can 'get away with' combining products sometimes, but you are on virgin territory most of the time, and have a sample of one or few to determine if it is actually going to work. You get the same arguments with most things...the comment "I've been doing it that way for years and never had issues" comes up often. And, things may work fine that way, but just like in the codes, where stuff that used to be done worked most of the time, newer codes were written to handle the 'what if' situations, the old methods just couldn't handle. There, especially, you get comments like "but it worked fine, why should you change it now?" come up. The manufacturer is the one that has the experience and depth of engineering to determine how their products perform, and how best to use them to provide a suitable result.

    What the OP started with was a fairly typical tub/shower install. Don't remember a window being discussed in the initial question. Those require special consideration in a major wet area like a shower, and I'd not feel comfortable trying a conventional waterproofing/moisture control method there which is what you've started. I'd much prefer a surface membrane since I feel it is more reliable, especially when dealing with a window.

    Otherwise, when using a surface applied waterproofing, it should be all or nothing, especially if you have plastic film behind the wall already. Adding some on the surface at the tub/wall junction will trap moisture there. If you can prevent any moisture from penetrating the wall entirely, as a surface membrane does, it's not a big deal - the cbu should never get wet IF you waterproof it properly. THere's a big IF there, which is why having something behind it as well as on it can be an issue. The only good thing about cbu in this case is that it does not degenerate if it does get wet.

    One reason why I'm proud of having working in the defense industry is that it forces a mindset to consider all of the 'what if' situations. You don't get a second chance in trying to detect an enemy's missile attack, or to shoot down an offensive missile or target intending to rain harm on you. IOW, you have to do it right the first time, and consider how to make sure it is highly reliable...this is a mindset, ingrained from years of work that carries over to other aspects of life. Innovation helps, you have to stay ahead of the enemy. In the case of a shower, the enemy is moisture, and controlling it is critical. It has to be done right, and mixing systems is risky, as they each approach the solution from a different viewpoint and methodology, and they don't always get better with picking and choosing parts of each system, or, as one here likes, to build one on top of the other. Best to stick with one and do it well.
    Last edited: Dec 24, 2013
  10. Jeff C

    Jeff C New Member

    Messages:
    9
    Location:
    NJ, USA
    First off gentlemen, thank you sooooooooo much for replying so quickly. I (and I'm sure my wife) truly appreciate it. I should have been more specific in my initial post, when I mentioned the window. The window is not actually in the tub/shower alcove, but rather about 2' outside of it above the toilet. The reason I metioned it at all was to infer that partly because of the window, shimming out the studs in the bath alcove, any more than I already have (1/4"), would be too big a pita. My tub alcove is pretty much like yours John (as seen in the photos of the tub at your house), except I don't have any soap/shampoo/etc. recesses built into the walls, and the wall opposite the tub/shower plumbing and drain is an exterior wall (insulated with non-faced R13 to prevent moisture being trapped in the wall). I had read the past post you referred to (about the install with the window that's actually in the shower. As shown in those other pics that you included) I believe that after looking at the new pics you posted (of the install in your own house) the solution to my dilemna is as follows:
    1. Pin tub to tub alcove wall studs (I know that the nails should not be driven tight to the tub flange, but rather have just a slight bit of "wiggle room". But, as per question 2 of my initial post, I'm still uncertain as to whether I need to fill the tub before pinning it to the studs)
    2. Attach KerdiBand to tub alcove wall studs, like you did in your photos, allowing bottom edge of KerdiBand to overlap tub flange (I'm going to overlap the height of the flange plus 1/2" to 1" extra, then after sealing the seam, trim the excess)
    3. Overlap the KerdiBand with my 6 mil plastic vapor barrier (KerdiBand under w/plastic over) by maybe 2-3", then trim excess 6 mil sheeting (this will create a shingle-like effect)
    4. Bring CBU down to 1/8" above tub tile flange, then using KerdiFix to adhere KerdiBand to tub flange
    5. Install the ceramic tile I'm using on the walls in the tub area, and finish off the tile to tub seam with silicon caulk (where tile meets tub deck)

    Does that sound plausible John?? And again, thanx in advance ...
  11. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    Sounds like a plan. Kerdifix is really good stuff, and will even seal underwater...got a small hole in a pool liner...no need to drain, it will seal a patch fine. You don't need both the Kerdiband and the plastic film behind there, but for that small distance, it won't hurt, and the Kerdiband is tougher than the plastic film, so it would be harder to tear. While cbu isn't affected by being wet, my preference is to never allow it to get wet in the first place, which is why I prefer a surface applied membrane. THen, there's also less to ever dry out. But again, ensure the tub ledges are level - you do not want water pooling, you want it to be able to drain off that shelf or all run to one end (or out into the room!).
  12. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Last edited: Mar 15, 2014
  13. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Temporary Shower Dam - Installation of Kerdi Band - Photo(s)

    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  14. Jeff C

    Jeff C New Member

    Messages:
    9
    Location:
    NJ, USA
    Gentlemen, sorry it took me so long to reply back to the thread. In addition to a busy holiday season, my mother passed away shortly after New Year's. It's been a hectic several weeks to say the least. John, in answer to your questions:
    Q: What brand of backer board are you using?
    A: HardiBacker 500

    Q: What size mesh tape will you use to tape the backer board seams?
    A: 2", self-adhesive, alkali-resistant, fiberglass mesh, cement-board tape

    Q: Do you have blocking in all corners of the backer board sheets?
    A: Yes, extra framing was added where needed, and the manufacturer's installation instructions were followed exactly (http://www.jameshardie.com/homeowner/pdf/backer-install-us.pdf). I also added 2x4 blocks in between all studs (except for the span, between the studs, where the mixing valve/bath plumbing prevents it), to not only give me more usable area in which to pin the tub to the walls/studs, but to also give me a solid, level surface to brace the KerdiBand/Poly-to-tub seam.

    ** Your install as described is on small step above bare minimum code. Make sure the steps I mentioned above get done.
    The steps you mentioned will get done (much to my wife's consternation, I give the term anality new meaning), but I must ask something. If the install method I described (entire bathroom covered in 1/2" green-board, except the shower/bath nook that has HardiBacker 500 on the walls, and green-board on the ceiling. Extra framing was added in the ceiling to allow green-board to be screwed 12" O.C. as per code. 6mil poly sheeting installed over studs as vapor barrier (with un-faced insulation used above the tub-flange area, and paper faced insulation used below the tub-flange area, on the one exterior wall), with all staples/any holes siliconed over to maintain structural/waterproof integrity. In addition, a small squirt of silicon was shot into each screw hole before screwing to studs so as to maintain structural/waterproof integrity. All cement board seams in the alcove were/or will be siliconed in a way that ensured additional waterproofing properties, but not so as to impede the adherence of the cement-board tape, or the thinset used to seal the taped seams (in other words, neither the tape, nor the thinset, comes into contact with the silicon behind the seams). The tube will be set in a bed of mortar/cement, leveled << shimmed as needed with a generous amount of construction adhesive under the tub-feet blocks >>, then pinned to the studs with S/S Truss-head screws. As per your instructions, the cbu-to-tub flange seam will be finished with 7" KerdiBand attached to the studs, then the 6mil poly trimmed, run over the top of the KerdiBand << I'm going 2" down from the top of the KerdiBand >>, trimmed, and sealed with Kerd-Fix. Then the KerdiBand will be brought over the tub flange, trimmed to length, and sealed to the tub flange with Kerdi-Fix. Finally, the last course of cbu will be put up, and brought down to within 1/8" of the top of the tub flange. All seams will will be taped with the cement board tape, and finished off with modified thinset. It will be all be finished off with tile.) is "one step above minimum code", then what would "over and above code" entail? Especially if waterproofing products like RedGuard, Nobel etc. are not being used?

    Q: The exterior wall - do you have the vapor barrier down to the bottom plate prior to setting in the tub?
    A. No, the 6mil plastic vapor barrier is over un-faced fiberglass insulation above the tub flange area, but below the tub-flange area, paper-faced insulation was used on the exterior wall, thus eliminating the need for the plastic sheeting.
  15. eurob

    eurob master tile and stone installer

    Messages:
    843
    Location:
    Montreal
    Most of these are true, however old methods work very well vs. the new methods(codes) -- 2" vs. 1 1/2" for showers , etc. --.

    Usually most of the mfg recommendations are important when warranties are in play , but nobody talks about the situations -- at least openly -- where the products fail. What you get is -- read the fine printing or you are the only one with this sort of failure or etc. --. Nothing is an absolute , but for the intended recommendation , for a DIY , stick with the printed literature from the mfg. Check it often or save a copy of it at the same date as your project is completed.
    Last edited: Jan 16, 2014
  16. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Post(s) deleted by John Whipple
    Last edited: Mar 15, 2014
  17. Jeff C

    Jeff C New Member

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    (disregard this reply - was testing to make sure that i can post images successfully)
    Last edited: Jan 23, 2014
  18. Jeff C

    Jeff C New Member

    Messages:
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    Location:
    NJ, USA
    Thanx again guys for all your help so far ... I'm going to lay the mortar bed, hopefully tomorrow (been busy clearing out my Mom's house getting it ready for sale, donating her belongings, all the will hoopla, etc.), and just wanted to answer the couple questions you asked John ...
    "So I am unclear on your local code for vapour barriers. You must follow local code here first - and then tie into this code approved and inspected step second. Do you have vapour barrier and insulation inspections?"
    Answer: No, we do not have vapor barrier and/or insulation inspections, at least not for what I'm doing (the bathroom renovation). There might be inspections of that nature for new construction, but again, I don't know. I did call my local building inspector to ask whether I needed a vapor barrier in the alcove, and much to my surprise he said, "No". He said that the CBU/Tile combination acts as a vapor barrier, and therefor I didn't "need" another. He said that I could use the 6mil poly sheeting behind the CBU as extra protection, but that it wasn't needed by code. To be quite honest, his answer doesn't make much sense to me as I was under the impression that both the CBU (HardiBacker 500) and the tile grout are both permeable, therefore a moisture barrier was needed. He also said (in relation to the same 6mil poly sheeting vapor barrier, on the exterior wall of the tub alcove) that I didn't need a vapor barrier there either (I suppose that if I was using paper faced insulation with taped seams I wouldn't), but surprised me again when I asked. "If I ever got vinyl siding put on the house, and wanted to wrap the house in Tyvek before the siding, would I have a problem of a double moisture barrier?" and he replied, "Yes!". He said that if I ever put up Tyvek, I'd have to remove the sheathing from the exterior of that small section of alcove wall, and slit the poly sheet vapor barrier, before wrapping the house with Tyvek. Doesn't make any sense to me, as although Tyvek is water resistant, it is highly breathable allowing water vapor to escape and thus avoid being trapped between two vapor barriers (in the wall). In any case, now I'm wondering if I should just say "screw the vapor barrier on the lower half of the the walls (The 6mil poly sheeting is already up, covered by HardiBacker, taped and thinsetted, on the top-most 36" of wall, nearest the ceiling). But if I can just re-install paper-faced insulation in the small section of exterior wall (thus eliminating the need for the poly), and skip the poly altogether in the other 2 (out of 3) walls of the alcove, then I could just use the KerdiBand, and install it the regular way (thin-setted to surface of the CBU, and sealed to the tub-flange with the Kerdi-Fix. What are your thoughts gentlemen? (see pics below...)

    Not the best approach to pin the tub with screws. Did you see how I did my daughters tub with the window clips?
    Answer: I did John, and if I can purchase those clips locally (stores like Lowes, Home Depot, Ace Hardware, True Value, etc.), then I'd love to go with the same solution. Where did you get those window clips from?

    2014-01-23 14.18.00VER2.jpg 2014-01-23 14.19.03VER2.jpg
    (MEASUREMENT IN 2ND PICTURE IS 39 3/4")
    Last edited: Jan 23, 2014
  19. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  20. Jeff C

    Jeff C New Member

    Messages:
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    Location:
    NJ, USA
    "Jeff does your exterior walls require vapour barriers? Yes - No."
    Answer: Yes, insulation is required. Either Kraft-faced, fiberglass insulation (with the Kraft side facing the warm side of the house) OR un-faced insulation with poly film over it, is acceptable.

    If yes why is the vapour barrier not in place below the tub that is shown now?
    Answer: The tub is not installed yet. It has simply been slid into the alcove to facilitate easier moving around in the work-space while I try to hammer out the final details on how to proceed on this project.

    I see blocking between studs but not between the two sheets (when second goes in).
    Answer: Sorry John, I have no idea what you mean. Are you saying that I need even more blocking between the studs?

    The pieces I held my daughter tub in place are window clips. Any building store should sell them....

    Answer: Well, I'll be checking the "big-box stores" later today to see if I can find similar ones, but so far both Ace Hardware and True-Value had nothing that even came close.

    Question: It appears that the whole root of my particular dilemma, is that friggin' poly sheet. SO, taking into account that my building inspector said that A. I do not need a vapor barrier on the interior long wall of the tub alcove, and B. That I do not need the plastic sheeting (as a vapor barrier) on the exterior wall as long as I'm using Kraft paper-faced insulation, I'm thinking I can end my confusion, and finish this project by just 1. Cutting the poly sheeting off below the first installed course of CBU (obviously I can't remove it, because it's covered by CBU). *** 2. Replace the non paper-faced insulation on the exterior wall with Kraft-faced insulation from the bottom of the existing course of CBU, all the way to the floor. *** 3. Installing the remaining CBU, then installing the Kerdi-Band as normal by embedding it in thin-set on the outside of the CBU, then sealing it to the tub-flange with Kerdi-Fix. Thoughts??
    BathroomProjectSolution.jpg
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