which waterproofing system for new shower?

Discussion in 'Shower & Bathtub Forum & Blog' started by ratherbefishing, Dec 10, 2011.

  1. ratherbefishing

    ratherbefishing New Member

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    Plumbing for my new bathroom is almost done. Insulating should go quickly. So, I'm on to thinking about the tile. The shower is 3x4', no tub; tile will probably go to the ceiling. I'll be making a mud bed. What waterproofing system do you guys recommend for a novice? I'd planned on Kerdi, after reading John Bridge's forum. Now I'm not so sure. Our local tile supplier sells Hydroment and Gold Plus. I've heard of RedGard, too.

    I've tiled a couple rooms, but never a bathroom. Which system is the best bet for a novice?

    Thanks!
     
  2. ratherbefishing

    ratherbefishing New Member

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    John,
    All that's done so far is the framing and plumbing rough-in. The shape and dimensions don't work for a store-bought pan, so I figure I'll build it myself. Walls will be 1/2"(?) cement board. Tiles haven't been selected yet, but my wife is leaning towards a subway shaped ceramic. Shower floor tiles will be smaller to accomodate the slope. The fella at the tile store recommended Gold Plus, a roll-on membrane.

    Oh yeah, I'm the plumber, too.
     
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    If you chose Kerdi, their recommended wall covering is drywall, larger sheets, fewer joints, cheaper. Since a properly built membrane shower keeps the moisture on the top side of the membrane, the drywall stays dry, and works fine. If it leaked, while the cbu wouldn't care, the structure would have problems, so leaks are a problem regardless, so choose whatever makes you feel happy, and don't look back second guessing. CBU works, too, but remember to wipe it down with a wet sponge first to take off the dust and to help prevent it sucking all of the moisture out of the thinset making installation harder and giving you less time. Other membranes, follow the manufacturer's recommendation on wall structure. A sheet membrane is sort of like putting up wallpaper, except it isn't critical matching patterns and an overlap is okay (you need one, whether it is the main sheet, or the manufactuer's banding material that can be added after or before the main sheets are applied, as long as you get the specified minimum overlap). The key with any membrane sheeting is to get the thinset mixed properly, and to use the proper premium type specified, and last, to pull a bit back off to check for proper coverage. The Kerdi drain is quite flexible as the square holding the grate can be easily moved during tiling to minimize cuts around it. My last one used 2x2 tile, and I was able to just cut four of them out of the mat and slide the center to perfectly align the gap...very neat and easy.
     
  5. dlarrivee

    dlarrivee New Member

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    Has anyone tried to use an airless paint sprayer to apply these liquid membranes?
     
  6. mtcummins

    mtcummins In the Trades

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    If you're using the Schluter products (Kerdi), you could get a 48x48 Schluter shower pan and cut it down to size. They're made to be cutable, so you'd just take 6" off 2 edges to get your 3x4 pan. This would save you the hassle/dry time of doing a mud bed.

    There may be other cut-able pans on the market, I'm not familiar with them if there are. These Schluter pans require Kerdi over them and a Kerdi Drain to make a water-tight system. Maybe you can use other products with their pan, but I don't know about that, I just use the complete Schluter system, as it was designed to be used all together.

    If you're going that route, you might as well just buy the whole shower kit and get everything in one shot. These generally run about $600.

    Lemme save JW the hassle, and tell you right now that he thinks they're junk, they're overpriced, they're marketing hype, that Jim and I are getting paid by Schluter to hock their junk, etc. Its all bullshit, but that's what you're about to hear.

    Choose the product you like (all of the ones JW likes are good products as well, if installed correctly), and install it properly, and you'll be fine.
     
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    IF the waterproofing membrane was also a wear surface (it is most certainly isn't), then thickness might be an issue. ALL are designed to be covered up with a wear surface, and MUST be protected prior to that happening. GoreTEx (TM) is MUCH thinner than Kerdi, and it works fine - because it isn't the wear surface - you NEVER see it as a top layer in clothing. Not saying GoreTex (TM) is a suitable tiling substrate, but this thickness argument just doesn't hold much water (pun intended!) with me. In a real situation, a thicker membrane can make corners harder to keep nice and flat. They ALL can get a hole poked into them, and if it does, it's poor workmanship. They ALL can be fixed, if that happens. ALL of the available membranes that have been approved (Kerdi has, along with many others) include a phrase like 'installed per manufactuer's instructions' that's part of the approval. Schluter recommends drywall, Kerdi is an approved method of waterproofing. Now, if you have a local code that doesn't allow it, it will work equally well installed over cbu, deckmud, a mudded wall, etc. It is NOT approved for use directly over wood, though, but most (all?) aren't. Choose whatever you prefer, but some people's rants against any one particular product are one person's rant, not the industries.
     
  8. mtcummins

    mtcummins In the Trades

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    I dunno Jim... thicker is always better in my experience...

    Thicker TVs make good designer statements and hold up better to their secondary use as a dartboard (when your team is doing poorly)
    Thicker underwear are nice and comfy
    Thicker glasses make for better vision (and more comfort on your face)
    Thicker phones fit in my pocket better
    Thicker skulls make smarter people

    C'mon Jim. Thicker is better. Get up to speed.
     
  9. ratherbefishing

    ratherbefishing New Member

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    JW, I am the tilesetter, plumber, framer and electrician on this project. So I'm learning a lot. The framing is straight and square, tho there may be a few more pieces of wood than an old pro woulda used. The last piece of Romex I ran looks better than the first, but they all passed inspection. I'm kinda proud of the copper in the crawl space. Looks almost like I knew what I was doing. But once I'm all done, all anyone will see is the tile. (Cr@p, I think I mighta made myself a little nervous there.)

    Time isn't that important, as I'm mostly working on the weekends. Money always counts, but I'll pay a little more for DIY friendly, if not idiot proof.

    Mike
     
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    The reason WHY drywall is allowed, is it is NOT in a wet area when Kerdi is properly installed. There should be no vapor or liquid water that gets to the drywall from the wet area, therefore not a wet area.

    From the Kerdi shower installation manual, it says solid backing materials for installing Kerdi, then, the section that describes what those suitable materials are (sorry, it didn't copy/paste with all the formatting, but it's all there):
    Solid Backing Materials

    Gypsum wallboard – ASTM C1396/C1396M

    Cementitious backer unit – ANSI A118.9 or ASTM C1325

    Fiber-cement underlayment – ASTM C1288

    Fiber-reinforced water-resistant gypsum backerboard/underlayment –

    ASTM C1278

    Coated glass mat water-resistant gypsum backerboard – ASTM C1178

    Portland cement mortar – ANSI A108.1B

    Concrete

    Masonry

    So, pick one that makes you and your local inspector happy, but ANY of these are approved.
     
    Last edited: Dec 10, 2011
  11. mtcummins

    mtcummins In the Trades

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    Question... why would it matter? Lets for a minute leave Kerdi and all of its "problems" out of the picture. And lets have an answer that isn't just about "approved uses," but an actual rational thinking answer.

    If your showers are so perfectly waterproof, who gives a crap if there's drywall behind it? It's only function is to provide a stable surface to attach the waterproofing to. Drywall is an acceptable substrate for backsplashes and other tile applications, so reason would state that it would be a sufficient substrate for a shower, if it was water tight. I thought your waterproofing was perfect, so the drywall behind a waterproof shower would actually be the best place to install it, as everywhere else, its exposed to a higher level of moisture and has a higher chance of becoming a mold problem.

    That said, I'm not advocating it as a substrate behind anything that it is not specified as acceptable by the manufacturer. Kerdi specifies it as an acceptable backing. It is not acceptable to use as a tile backer w/o waterproofing in a shower, which would be a "wet zone"... can't tell you how many times I've seen that... "Ceramic tile is waterproof, right?"
     
  12. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Re things like glass tile. The Kerdi instructions say to call the tile manufacturer AND Schluter to come up with a suitable workaround, if it is possible. Since the requirements can be quite stringent, and you want a warranty from both the tile and the membrane user, that collaberation is required. Chances are, you can get a suitable, warranteed install, but you need to ask. Since the exact solution may vary, they require the collaberation consulation before approval. Just like you may need approval from your local building inspector if you want to do something outside the norm. If that's too much trouble, use a different product.
     
  13. mtcummins

    mtcummins In the Trades

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    I love how much confidence you have in your perfect waterproofing. Properly waterproofed drywall behind a shower wall will NEVER grow mold. The MR gyp board that you put next to the shower is 10 times as likely to mold. Simple as that.

    Don't install waterproofing on drywall that the manufacturer doesn't allow.

    Your code reference is for Tile on Gyp board, thinset method. Not tile on gyp board, waterproofing then thinset method. Clearly its a dumb-ass idea to put up drywall and then tile in a shower. I tear those out from time to time, especially in tub surrounds. That is a different installation.

    Turns out OSB is not an acceptable roofing surface, unless you put a proper waterproof roof over top of it. Hmm... odd how that works, eh?

    If you don't want to use it, put in CMU, form a mold and pour a monolithic slab of concrete and use a pool liner before waterproofing, whatever makes you happy. Kerdi over drywall is accepted in the US, maybe Canada is different.
     
  14. mtcummins

    mtcummins In the Trades

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    You've sited many places that very obviously state not to use gyp board as a tile backer in a shower. Good for you. You've not cited anything about the substrate of a completely waterproofed area. There is a difference.

    Show me code that says you can't put kerdi on drywall.

    More than that, tell me WHY a perfectly waterproof system is ever going to mold the drywall behind it. It won't happen, unless you have a leak in the wall, in which case you're pretty much screwed either way. The walls surrounding a shower or tub are far more susceptible to water damage/mold. You don't seem to have any actual answer, just some vague references to code that does not specifically state what you are claiming.
     
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Refer to TCNA installation instruction B421.07, ANSI 118.10, and IPC as described in the test report linked http://www.johnbridge.com/images/mike2/For%20Liberry%20Stuff/ICC%20ESR-2467.pdf

    Additionally, Kerdi, installed per the manufacturer's instructions, is approved by state building codes notorious for their unique take on things in Massachusetts, Michigan, and Kentucky for places that may not adhere to the IPC, when building a shower. The TCNA 421.07 allows drywall (gypsum board).

    Now, if your local codes modify these, then you must adhere to those. Just like Canada allows 1.5" drains for showers and the USA requires 2", each jurisdiction can dictate what you should use, but the test results show that, properly applied over a backing material, Kerdi is waterproof and is a decent vapor barrier. If you were in a commercial situation and required greater vapor retardation than the 0.75perm rating on Kerdi, then you'd want to install it over something else, but this is more than sufficient for any typical home use and many light commercial uses. Since it is waterPROOF, the backer material is not wet.
     
  16. mcu

    mcu New Member

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    mtcummunins, do you use thinset alone to do the kerdi membrane and base or also chaulking that JW is talking about? Do you use preformed shower curbs and benches or build your own?
     
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    If you want a hanging bench, either corner or along a wall, I like the Innovis Better Bench. If you're going to build a Kerdi shower, you could use either Kerdiboard to form it, a monument bench, or something like the BetterBench. There are other companies that make similar products. Using Kerdiboard means the whole bench is waterproof. A monument bench is built inside the waterproofing. The Better Bench is installed after the waterproofing, and can be installed either before or after the tile is installed. Or, you can build the bench out of wood, cover it with ply, then either drywall or backer board, then cover the whole thing with Kerdi while doing the rest of the shower.
     
  18. mtcummins

    mtcummins In the Trades

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    I'm not sure what you mean by "thinset alone," but i like the schluter base, thinsetted down to the subfloor, then kerdi installed over that. I haven't built any huge showers, mine have pretty much all been 30-32" wide, but what I like to do is use basic roofing principles with the kerdi... start at the bottom, run the kerdi horizontally through the corners w/o seams, and overlap the edges bottom to top. This relies very little on the thinset for waterproofing, only wicking can get water past the seam. It does make the overlap area thicker than using the kerdi band, but i prefer this system. Alternatively, you could put the sheet on the wall, band over the edge and up onto your backer board, then bring the next sheet of kerdi down to the top edge of the lower sheet (rather than putting the band on top of the seam, you're lapping it like a roof). This would save you some thickness.

    Anyway, back to the width... one of the things that narrow showers lets you do is run the floor piece up the walls... i center the bottom sheet w/o cutting it to width, cut out the corners, and run the edge of the 39" sheet a few inches up the wall on all edges. Then I add the corners, then bring the first wall sheet all the way to the bottom of the wall. You have to get those corners in tight (squeeze out a bit more thinset than normal), or the buildup can be too much. Again, this is roofing style... don't count on the thinset seams much, but rather the lapping of the sheet.

    It is difficult to manage a sheet long enough to wrap all the way around the shower, but its worth it to me to not have seams in the inside corners.

    I have used the preformed curbs mostly, but I don't think they're necessary if you do a meticulous waterproofing job. You could just as easily, and much more cheaply, build your own. But, the extra time to do that isn't really worth it to me, so I generally just get the $50 curb in the kit and use it. I've not used any of the pre-made benches. I've always had very specific requirements for them, so I like to custom build them. Same thing with niches, they really need to be custom built to be able to get exactly what you want. I'm sure some of the bench options out there are good ones, but you don't want to ask me about that, as I don't have any experience with them. For example, the shower I'm doing next is 5 feet long at the shower pan, but then steps up for the bench, and out an additional foot. This space is suspended over a staircase. Its a maximizing space move, and one that has to be custom made for the application. It's also critical that the bench then gets completely waterproofed, as its not over a pan anymore...

    I like the valve seals and such they offer as well... keep it all sealed up tight.
     
  19. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Is 1/8" glass any less waterproof than 1/2" glass? Kerdi passes the ANSI 118.10 test as a waterproof membrane.
     
  20. mtcummins

    mtcummins In the Trades

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    Hmm... so you mean to tell me that the top tech at Schluter, who is on a chair of one of the many organizations names that you like to throw around (without referencing anything that actually says what you're claiming), along with all the other Schluter higher ups who are on other boards, allowed the Schluter SHOWER system instructions to specifically list Drywall as one of the proper substrates (and actually the FIRST in the list of substrates), when the organizations they chair supposedly say that it is totally unallowable? Hmm, thanks for convincing me that you're full of crap once again.
     
  21. mtcummins

    mtcummins In the Trades

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    JW, why don't you try reading sometime, rather than just responding with crap.

    http://www.schluter.com/media/ShowerHandbook.pdf

    NOTE: this is the SHOWER, let me repeat, SHOWER installation handbook from your reps that are on all your boards. One more time, this installation manual is for installing SHOWERS, not backsplashes, or whatever else you're claiming w/o any basis. Look at page 2, then look at page 5, then how about page 7, oh, then there it is again on page 9. Oh wait, not done yet, there it is again on page 11. Then there are the pictures on page 12, 14, 15, 17, 19. There's probably a lot more, but I'm already tired of being right.

    I will note one more thing... Read page 19. It specifically talks about protecting gypsum board in a wet zone with kerdi. Hmm... that doesn't sound like the bull crap you've been saying on here...
     
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