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Other Moisture Barriers Besides Kerdi for Shower

Posted by sonepi (My Page) on
Sat, Jun 5, 10 at 23:56

I have read most of the posts here on Kerdi and that definitely seems the way to go, but just wondering if it is something regional or fairly new. I was at a bathroom designer showroom where they had part of the shower removed so you could see the layers of their work. They used a bright orange kind of thick plastic sheeting for their moisture barrier.

I am planning on having tile people come in to give bids for redoing our Master floor and shower area and wanted to know what other types of material are used to help keep moisture from going through tile. We will have a tile shower floor instead of the acrylic shower pan. It will be enlarged to about 45 to 48" square.

I guess I have a few questions:

1. What are the layers or steps that should be done to have a good shower construction/install?

2. Green board vs cement board vs other options in the shower? I've heard of something called Denshield. Is this something to consider?

3. What are some of the other types of moisture barrier besides Kerdi that may be used that would be effective?

4. What are some things to definitely avoid in an shower tile install?

With your help I can do some additional research so I will know the questions to ask the installer to make sure their process will get me the best outcome. Anything else you might suggest I know would be appreciated.


Follow-Up Postings:

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RE: Other Moisture Barriers Besides Kerdi for Shower

All my opinion.

There are two basic families of waterproofing membranes for showers. I'll use my own wording and refer to one as "traditional" and the other as "topical".

A traditional shower base would have the waterproofing membrane buried somewhere in the floor or wall. Working up from subfloor to tile, has a slip sheet, then expanded diamond mesh, then a deck mud preslope, then a relatively thick 40-mil (or so) membrane, usually CPE (chlorinated polyethylene) or CPVC (chlorinated polyvinylchloride). It's crucial that the membrane go on top of a sloped surface so that the membrane itself is sloped. On top of the membrane will be the tiling bed which is another thickness of deck mud, then thinset and tile.

You can see this on Harry Dunbar's site.

With that "traditional" base, you'll have traditional walls. Wood framing, then a waterproofing or drainage membrane (lapped tar paper or 6-mil poly sheeting) over the framing, then cement board over that, then thinset and tile.

So that's "traditional".

"Topical" would be having the membrane on the face or front side of the material that's to be tiled on instead of behind it, buried in the wall or buried in the floor. The advantage of topical is that all that can really get wet is the tile and the thinset. In a traditional shower the tile, thinset and cement board can get wet in the walls, or the tile, thinset, and deck mud tiling bed can get wet in the floor.

Both methods are fine, but topical does allow for better moisture control. My opinion.

Topical can be a fabric-covered tile-on sheet membrane like Kerdi or Nobel.

Topical can be a roll-on or trowel-on membrane like HydroBan, RedGard, Ultraset, or any of the several others that is applied over the appropriate substrate, in the appropriate mil thickness, with the appropriate number of coatings. These membranes, I recommend going to the manufacturer's specific websites to see the appropriate backer that they can be applied to. Some need reinforcing mesh or fabric in corners and over gapped panel joints.

Topical can be a sheet material like Wediboard, KerdiBoard, or even though I'll personally never use it but since you mentioned it, Denshield, applied directly to the wood framing. With sheetgoods all fastener penetration holes and panel seams need to be appropriately waterproofed.

Outside of the shower area, to waterproof the remainder of the bathroom floor all I've been using is Ditra with Kerdi over the seams.

So for your questions:

1) I hope I detailed that above.

2) No greenboard as a tile backer in a shower or tub surround. It's a code violation. 1/2" Cement board is excellent, and it can be used as a backer for all topical membranes in a "topical" shower. Or with poly sheeting between it and the wood framing, it can be used as a tile backer in a "traditional" shower.

3) Listed above

4) Worst mistake in a "traditional shower" is the membrane going flat on the subfloor and then sloped deck mud going on top of that. Remember, a PRESLOPE had to go in first, then the traditional membrane on top of that so that the membrane is sloped. Then more mud, then tile.

Worst mistake in "topical" membrane showers is not following the manufacturer's installation instructions. Kerdi and Nobel sheet membrane are pretty much bulletproof IF you follow the manufacturer's instructions. The roll-on membranes are excellent as long as they are applied at the proper thickness and reinforcing fabric is used where specified.

With sheet good materials like Wediboard, KerdiBoard, the worst mistake is not detailing fastener heads or cut panel edges.

With Denshield, I won't comment on it as I don't to use it.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Not that I can add much of value to mongo's post but I can share what we did/used in our guest bathroom and are in the process of doing/using in the MB and will be doing/using in the hall bath.

We used a cast iron shower pan in the guest bathroom. Shower walls are hardibacker (cement board). DH used Hydroban (from Laticrete) for the waterproofing membrane (two coats as per the instructions). Tile was installed with thinset, and then grouted with TEC grout (Accucolor, I think). I don't recall what DH type of "rock" used for the walls in the rest of the room--no tile outside of shower stall (except small backsplash over the sink).

MB--same wall/waterproofing materials in tub area (cast iron tub). Tile will be up to and including the ceiling around the tub. Grout will be TEC XT; new-ish grout from TEC that is more stain and crack resistant, as well as mold and mildew resistant (has anti-bacteriacide in dry form in it). Walls and ceiling in remainder of room are purple board (better than greenboard)--those walls will be painted, not tiled (except over the vanity, up to the ceiling).

Plan to do the same in the hall bath.

HTH


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Your waterproofing choices

Posted by Mongo;

"So for your questions:

1) I hope I detailed that above.

2) No greenboard as a tile backer in a shower or tub surround. It's a code violation. 1/2" Cement board is excellent, and it can be used as a backer for all topical membranes in a "topical" shower. Or with poly sheeting between it and the wood framing, it can be used as a tile backer in a "traditional" shower.

3) Listed above

4) Worst mistake in a "traditional shower" is the membrane going flat on the subfloor and then sloped deck mud going on top of that. Remember, a PRESLOPE had to go in first, then the traditional membrane on top of that so that the membrane is sloped. Then more mud, then tile.

Worst mistake in "topical" membrane showers is not following the manufacturer's installation instructions. Kerdi and Nobel sheet membrane are pretty much bulletproof IF you follow the manufacturer's instructions. The roll-on membranes are excellent as long as they are applied at the proper thickness and reinforcing fabric is used where specified.

With sheet good materials like Wediboard, KerdiBoard, the worst mistake is not detailing fastener heads or cut panel edges.

With Denshield, I won't comment on it as I don't to use it."

Some expanded info on Mongo's post.

2). Green EBoard the ECO friendly backer board is most likely approved in your town.

3). Hydro Ban is my waterproofing product of choice and the same of many of the top people in North America.

4). The most important point in this topic. Pre-slope before waterproofing. This is key people!!!


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RE: Other Moisture Barriers Besides Kerdi for Shower

Thank YOU! Exactly the information I was looking for. I have had a few contractors come in. Now I need to ask more pointed questions. The one that started my mind to thinking about these questions was that he puts up cement board and then tiles after putting on mud. I asked about water proofing, like with Kerdi, but he did not seem to have heard of this product. He has several references that sound good, but maybe there hasn't been a leak yet.

It sounds like the bottom line is that there DOES need to be a waterproofing barrier of some type other than just using cement board. It can be over the framing with traditional. Topical would be waterproof membrane over the mud prior to tiling and after the cement board.

What I should beware of is an installer that does not use a separate moisture barrier of any kind besides cement board and mud. If the installer's step is a flat subfloor and building the mud up to slope it, that should ring an alarn bell. From the posts it sounds like the subfloor should be pre-sloped first, then a waterproof membrane of some type, then mud, then tile. Honestly, he did not say any of these things, but I will see what his process and steps are. He may have just been trying to be brief. The GC swears by him, but I am concerned about potential leaks. I definitely want beautiful tile work, but I also want has much water protection as possible.

I'll let you know what he says when I get more detail.


Thank you all soooo much. I hope I end up asking the right questions. I'll definitely ask about Hydroban


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RE: Other Moisture Barriers Besides Kerdi for Shower

quote: "Thank you all soooo much. I hope I end up asking the right questions. "

sonepi, allow me to correct a couple things.

I'll add some more background information too.

Your 3rd paragraph starts with "What I should beware of is an installer that does not use a separate moisture barrier of any kind besides cement board and mud. " Perhaps you would write that differently if you had more time to self-edit, or perhaps not, so I'm going to make it 100% clear here now, that it is wrong in every way to make it sound like cement board and mud are a barrier for anything H20-related. Whether it's called moisture, vapor, water, humidity, mold or any other term, the cementitious part of a shower is not a barrier for this.

The H20 barrier is another product made bought and sold as a shower membrane product. Mongo mentioned many types. There are even more types of shower membranes than that, too. And they are all good. Don't worry about the product. I repeat, that they are all good.

Your four questions in your original post are apparently good questions, to a novice.
The last of the four questions is a killer: "things to definitely avoid", and to this Mongo answered essentially this: Avoid installing the membrane as a flat install with the floor slope built on top of it, so in other words, first PRE-slope the structure before any of the possible membranes get installed."
It was and still is the killer question.
Your three questions preceding this killer question are more like indicators of YOUR knowledge today, and not the sharpest questions (If I may be so kind as to tell you this now).

--
I hope my post has cleared up the confusion already. Keep reading.

In your 2nd paragraph in last's night post, you also said "It sounds like the bottom line is that there DOES need to be a waterproofing barrier of some type other than just using cement board. It can be over the framing with traditional. Topical would be waterproof membrane over the mud prior to tiling and after the cement board."
True : "need waterproofing barrier" and cannot rely on "... just using cement board."
False to equate "... waterproofing barrier ... cement board" but I'll bet that is just due to sloppy editing.

--
You also wrote "If the installer's step is a flat subfloor and building the mud up to slope it, that should ring an alarn bell."
This is wrong.
Once again, with more time to edit, you might have written it more like this:
"If the installer's step is a flat MEMBRANE and then building the mud up to make a floor slope, that should ring an alarn bell."

You want a slope, and you certainly CAN have it built with mud.
You don't want the membrane to be flat, under a built-up slope.
You do want the membrane to be sloped, on a sloped floor.

You did say it correctly in your conclusion. You wrote "From the posts it sounds like the subfloor should be pre-sloped first, then a waterproof membrane of some type, then mud, then tile. Honestly, he did not say any of these things, but I will see what his process and steps are. He may have just been trying to be brief. The GC swears by him, but I am concerned about potential leaks. I definitely want beautiful tile work, but I also want has much water protection as possible"
This part is correct.
Please note that saying "mud" might mean thinset+tile to some, and might mean a big slope build-up to others. You could just say "tile it"

To answer your first question about "steps that should be done" :
Slope is the first thing. Membraning the slope is next.
Mongo said this. Mongo gave more information too. John FRW said this too. John FRW said "the most important point in this topic. Pre-slope before waterproofing. This is key"

Your second question is about wall product "to consider".
There is NO need to think about wall product, as the membrane does the job of making it a shower.
Mongo said this. Mongo gave more information too. John FRW wrote about 1 product he loves today. It's irrelevant.

Your third question is about "some of the other types of moisture barrier besides K...rdi"
There are sheet membranes that you unroll, and you need to seal the sheet overlap.
There are liquid membranes that you paint, roller, trowel on.
There are board membranes that you screw on and then seal the seams of (and the screw holes) with a caulk.
Mongo said this, in his own way. Mongo gave more information too. John FRW wrote about 1 product he loves today. It's not helpful information, since your installer may be best using what he already uses. Do not ask your installer about Hydroban. Do not focus on the product.

--

Your recommended installer has to confirm to you two things only:
A.) that he knows how to seal the membrane he uses, and
B.) that he handles the sloped floor by membraning it after it's sloped instead of installing the membrane flat.
Ask questions in a way that make him correct your mistakes instead of feeding him the answer you want.
Any membrane is good.

---

On the internet, Kerdi is definitely the way it often seems to go.
In reality, not on the internet, things are "real".

The Kerdi manufacturer has invested in making internet advisors into Kerdi users.
Free courses, free product, advertising dollars, and more.
They can even create profiles of people asking in a way that is mistaken so that good people can rush in and correct them.
Then, these internet queries can all end up "deciding" to use Kerdi, no matter how the thread started out. I've seen this happen hundreds of times at one Kerdi-sponsored advisor site.

--
David


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Mongo, in the future

Mongo,

Let's see if we agree on a strategy.
In a first reply, keep it short and general.
Not writing out the long answer first.

The above thread is a good example.
The more you wrote, the more it was good in every way, to me, but...
But it went over his head.
He didn't get it.
Last night he paraphrased by equating cement board with membraning,
In one of his sentences, when he might have meant membraning, he wrote "subfloor".
Talk about confusion!

Reframing "that the questions they REALLY want to ask are the following" is a great way to communicate.
Telling novices that they are asking the wrong questions is a good thing for them.
Not answering his questions would have been better for him.
Telling him less would have helped him more.

hth


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RE: Other Moisture Barriers Besides Kerdi for Shower

"If the installer's step is a flat subfloor and building the mud up to slope it, that should ring an alarn bell. From the posts it sounds like the subfloor should be pre-sloped first, then a waterproof membrane of some type, then mud, then tile."

Wow... lots of info up there for a newbie.

As a DIY, it took me over a year of reading all sorts of postings about all this stuff before I really started to understand everything. The shower pan part was the most mysterious to me, so I think I understand a little of your confusion with terminology. Actually, I wouldn't even consider building a showerpan myself due to the simple concept but need for meticulous correct/skilled construction.

So, just to pick up the semantics that you may have confused, the one thing you wrote that I quoted stood out.

It's not the "subfloor" that is "pre-sloped". Your subfloor is your subfloor and it is flat. The correct shower pan construct includes a few parts aimed at making sure that water does not just sit and collect but rather is directed to the drain. (your flat subfloor followed by a mud preslope followed by your membrane followed by more mud also sloped then thinset and tile). Unless a "topical system" like Kerdi/Noble are use, the are on top, no preslope is needed, just slope.

I think the thing I found most amazing was that water actually was seeping through everything in the traditional constructs. I just couldn't imagine that this was meant to be. But, so it is. When I deconstructed my 50+ year old shower I saw the way it all worked, and actually mine was in the process of failing- good timing!

Read Mongo's again. He specifically answered your question about waterproofing and vapor barriers (all good), as well as what to look for as one of the major failures in shower installs- an incorrectly fabricated showerpan.

So for me, the concepts are as follows in layman's terms, as I am simply that!

Traditional methods are meant to correctly handle moisture and water that will expectedly seep through the expected layers thus preventing moisture and mold damage to your home structure.

More contemporary methods simply prevent the seepage of moisture and water beyond that topical layer.

Either done correctly are valid. But I will add my 2 cents here- if one lives in a damp area, perhaps the more contemporary methods would be preferred? It makes for less moisture residual altogether!

I found all the postings a bit overwhelming, so you should post more questions if you got confused. I hope my fellow student perspective on all that was more helpful than just more words!


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RE: Other Moisture Barriers Besides Kerdi for Shower

"Mongo,

Let's see if we agree on a strategy.
In a first reply, keep it short and general. "

Okay.


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Ain't be no schill

"The Kerdi manufacturer has invested in making internet advisors into Kerdi users.
Free courses, free product, advertising dollars, and more. "

David, realize that I am not one of those people. I've never gotten anything from Schluter. Well, once I did get a paper cut from one of their brochures.

Ironically, the only company that ever gave me free product was Wedi, which I remember being your favorite. A rep was at the supply house when I was making a purchase and gave me a load of material.

You won't see me recommending anything but what I believe to be a solid solution to someone's problem. Might not be the only solution or your solution. It's just one solution.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Okay. Keep the comments coming. First of all he, is a she. LOL So my terminology is probably not up to par and I am probably even less than a novice when it come to tiling things...hence my questions. Thank you all for taking the time to post clarifications, details, corrections and restatement.

Hi David your quote, "Your three questions preceding this killer question are more like indicators of YOUR knowledge today, and not the sharpest questions (If I may be so kind as to tell you this now)." The 3 you mentioned were not really questions. You were correct in that I was trying to make sure my understanding of the previous posts was on point and correct. I was tired, it was almost 1:00 a.m so I was not as clear as I should have been, but I wanted to respond. Forgive me for that. You're right, my editing sucked! ;-) It still might suck today, but I will try to be more careful.

Yes, I understood that cement board and mud were not waterproofing and I should not have said "other than cement board." I also understood there were several products that can address this issue. Regarding my statement , "If the installer's step is a flat subfloor and building the mud up to slope it, that should ring an alarn bell." Thank you for clarifying and expounding on that. I DID NOT have it clear enough in my head. I am glad you explained it further.

My understanding now is that the "membrane" should not be flat, it should be sloped, but the installer can get that slope through various means depending on which technique is used. However he does it, the membrane should never be flat. Glad I got it right in the conclusion. Mongo stated this and I should have read it more than once before responding. LOL

I like the two statements of WHAT YOUR INSTALLER HAS TO CONFIRM. It seems like there should really be a third...some variation of what do you use for waterproofing or do you use any type of waterproofing membrane? Again, from what he stated, he may not actually use any type of membrane or barrierthat was why I initially asked my question on the forum.

Now to David about Mongos response. Mongos post was VERY helpful, it got me to thinking. You really cant fault Mongo for my poor use of words, i.e. equating cement board with membraningwhich I know is not the same. My use of the word subfloor just showed my own ignorance about the correct terminology. When I used the term subfloor I was thinking whatever was on the floor before they did the mud (might not be he right word eitherforgive me in advance) to create the slope. I want to apologize if my terminology confused anyone. You know how it is that you know what you mean, but may not know the proper word for it.

As a quasi-novice, telling me I am asking the wrong question is not useful, because if a person doesnt know a topic then they really dont know WHAT questions to ask. Saying that though, David your reframing the question to what you think I meant to ask or what I should have asked IS VERY helpful. So if you knock me about asking the wrong question, I forgive you if you reframe or state the question I should have asked. ☺

Boys, boys. I like both, brief and also detailed responses. Mongo wrote a great response to my question and I blame myself for not reading it thoroughly. David you stepped in to make sure I understood what Mongo had written. You BOTH furthered my knowledge base.

David I have to disagree with you though. Your statement, "Not answering his questions would have been better for him. 
Telling him less would have helped him more." That was sooooooooo wrong. Not having anyone answer my questions would have left me as ignorant about the shower tiling process as I was before I posted. I would prefer to get a response, which by the way Mongo gave an excellent initial responsethan no response at all.

Pepperidge You hit the nail right on the headI am a newbieokay even less than a newbie, but I try to get as much info as I can before having someone come to my home. If I am shopping for carpet, I read up on it. My confusion is that I could not get a clear answer with reading stuff on the web. It was conflicting, confusing, and many seemed biased towards a certain product or system. I knew if I posted here, someone would help me. Thank you for clearing up the subfloor statement. I WAS incorrect in my thinking. I WAS thinking they could slope the subfloor to get the slope, but you corrected that for me.

Dont worry. I have no problems asking questions or showing my lack of knowledge (ignorance) about a topic.

I want to thank ALL of you for your comments. They have helped me immensely.


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clarification

sonepi, a couple of follow-ups:

"It sounds like the bottom line is that there DOES need to be a waterproofing barrier of some type other than just using cement board."

Cement board is not waterproof. It won't be damaged by water, but it it not waterproof. So yes, you either want a membrane behind the cement board, between the cement board and the wood framing. If you do that you then thinset and tile right on the cement board.

If no membrane goes behind the cement board then you have to have a membrane applied to the front of the cement board. In that case, after the membrane has dried/cured, you'll apply the thinset to and tile directly on the cured membrane.

"If the installer's step is a flat subfloor and building the mud up to slope it, that should ring an alarn bell. "

Not necessarily. Did you watch the steps taken in this link that I posted way back when? That link shows how to do what I referred to as a traditional shower pan in my previous post.

You start with a flat wood subfloor. Then a slip sheet and wire mesh are placed on that. THEN you create a sloped "preslope" out of deck mud right on top of the flat wood subfloor. Then the membrane goes on top of the mud preslope, which causes the membrane to be sloped. Then another layer of mud goes on top of the sloped membrane. Then thinset and tile on that second layer of mud.

If your guy places the membrane on a flat wood subfloor and then places sloped mud over that, the membrane is flat...that is a huge no-no.

Go watch that link I embedded in this post. Step-by-step.


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RE: Other Moisture Barriers Besides Kerdi for Shower

sonepi if your installer hasn't mentioned membranes so far, I don't think that means anything yet. I'm sure there is a membrane. Ask about it, and ask at what point it gets installed. Under which layers.

Sooner or later the installer will mention the slope he has to build, and this is where you start listening real close, prodding him to keep on explaining. He could say the membrane HAS to be on top of the slope, or he could say something fuzzy or evasive or whatever, and if so this is a warning sign. You could giggle and go along with it and say yeah it don't matter let's not be fussy let's not concern ourselves about whether it'll last 20 years, we're just gonna git this thing built aren't we. If he corrects you and says the membrane has to go on top of the new slope, you have a winner.

Code requires membranes to be sloped, as far as I know. (Membranes on floors).

Regardless of code, if the membrane is installed flat, what happens? Water seeps in, and stagnates. Within a year it smells. You will not be satisfied. It can soon smell so bad, it hurts. When it disintegrates, or when you rip it out, the smell released can be so strong, it will stun everyone in the vicinity. Regardless of the intensity of the smell, the failure of the install is guaranteed, either 99.5% or 90% or whatever large number you wish (statistics based on anecdotal evidence and will vary)

hth


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RE: Other Moisture Barriers Besides Kerdi for Shower

Mongo,

I found all of the information you gave to be very helpful, as I was looking for exactly that information and haven't been able to find it elsewhere. I find your posts to be very clearly written. If there is some source of confusion, I'm sure someone will jump in for clarification, but please do not stop giving out detailed information and writing lengthy posts. The more information, the better. I appreciate the time you take to help people in this forum and I have learned tons from your posts.


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RE: Other Moisture Barriers Besides Kerdi for Shower

kitchenkrazed,

Thanks. If I can answer in one word, I shall do that. If I need more I use what I deem appropriate. Depends on how I feel at that moment in time.

I do understand David's concern. Some questions are somewhat open-ended; "how do I tile my bathroom". Instead of writing a book the best approach is to qualify the initial poster's question with questions of our own to narrow the focus of the thread and to provide a specific and proper answer.

Sonepi provided a little background, then asked four questions. Then asked an open-ended question at the end of the post. I answered them as I felt appropriate.

Sometimes my replies will be tempered by my own schedule. If I know I'll be checking in on the forum in the near future then I might write a quick reply anticipating a bit of back and forth over the course of the next couple of days. If I won't be on the forum for several days, then I might try to write something more lengthy and detailed. It all depends.

No worries.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Code requires membranes to be sloped, as far as I know. (Membranes on floors).

Required by International Residential Code (IRC), American National Standards Institute (ANSI), Tile Council of North America (TCNA) and Universal Plumbers Code (UPC). The following is the UPC language, but all are either exactly the same, or very similar:

Uniform Plumbing Code related to shower pan construction.

"412.8 When the construction of on-site built-up shower receptors is
permitted by the Administrative Authority, one of the following means shall
be employed:
(1) Shower receptors built directly on the ground:
Shower receptors built directly on the ground shall be watertight and shall
be constructed from approved type dense, non-absorbent and non-corrosive
materials. Each such receptor shall be adequately reinforced, shall be
provided with an approved flanged floor drain designed to make a watertight
joint in the floor, and shall have smooth, impervious, and durable surfaces.
(2) Shower receptors built above ground:
When shower receptors are built above ground the sub-floor and rough side of
walls to a height of not less than three (3) inches (76 mm) above the top of
the finished dam or threshold shall be first lined with sheet plastic*,
lead* or copper* or shall be lined with other durable and watertight
materials.
All lining materials shall be pitched one-quarter (1/4) inch per foot
(20.9 mm/m) to weep holes in the subdrain of a smooth and solidly formed
sub-base.
All such lining materials shall extend upward on the rough jambs
of the shower opening to a point no less
than three (3) inches (76 mm) above the top of the finished dam or threshold
and shall extend outward over the top of the rough threshold and be turned
over and fastened on the outside face of both the rough threshold and the
jambs.

As for the part about Schluter "buying" support from pros like myself, it IS customary for manufacturers to give away all kinds of logo bearing swag. Of all the manufacturers I've dealt with, the ONLY thing I've ever received from Schluter was carpenter's pencils. No t-shirts, sweatshirts, not even pads of paper.

As for free product, I mentioned to the regional rep the other day that I was getting ready to do some extensive tile work to my own home, and asked what the chances are that I might be able to get a large roll of Ditra. His answer was that the chances were very good-- that he was sure that Daltile's warehouse stocks them, so I could buy one there at any time.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Okay, I'm back. ;-) I talked to the tile guy today. My questions or statements are in quotes, his are not.

Here is what he said...We put up backer board. Some people use Hardibacker but I usually use cement board. It's waterproof so it does fine. "So thats all you need on the walls?" I sometimes use Aqua Touch its a cement board, but its waterproof too. Sometimes you have these cracks so I waterproof it like with silicone to fill the cracks. "What cracks?" Sometimes there are little cracks and I fill them with silicone and then when you put the boards together there will be cracks. "Like when they put up drywall and the two pieces meet like at the seams? I sew a little bit. " Yeah, the seams. What I do is I'll cover up those seams with the silicone to make sure it's stays waterproof. "So is that all you need to do to make it waterproof?" He said yeah.

I asked about the tile pan floor. He said we use a sand mix, it's not really sand, it's just concrete without the rocks. So after we demo the walls, we put the sand mix down then we put the rubber liner over the mix up to about a foot up the wall. "So, the rubber liner thing doesn't go over the entire wall?" No it just goes on the floor pan area and up about a foot on the wall. The cement board is all you need on the walls and the silicone for any cracks. I lay the floor first. "So you tile over the rubber part?" No, we have to put some more sand mix down to make the slope. That's so the water will drain into the drain when you take a shower. "So then you tile over that after you put the rubber liner down?" Yes. "So the rubber thing only goes up a foot? I just need to get this right so I can tell my husband. "Yeah, you don't need anything more than that because if you are going to have water problems it's going to be where it drains, not on the wall, 'cause the water will be falling to the floor. I do the floor, then the wall tile except the last row row of wall tile because I want to put the wall on top of the floor tile. Thats to make sure the water doesnt end up anywhere but the floor.

I asked about the curb walk entrance level so it wouldnt seem like I was so focused on the water barrier process he used. "How high is the walk-in curb?" About 4 1/2 inches. "Could it be shorter?" Well it's 4 1/2" on the outside, but the inside is only about 2" cause we have to build up the floor to do the shower pan. It could probably be a little shorter. If you or your husband have any more questions, just call me anytime.

Based on this conversation, your thoughts? He did not allay my concerns and kind of confirmed my initial instincts. Thanks everyone again.


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RE: Other Moisture Barriers Besides Kerdi for Shower

In mongo's first response he described "traditional". This guy's methods are in that field. His shower floors may be good.

The guy didn't tell you about "poly", a plastic barrier behind the cement board, and he didn't answer those wall questions well when he kept on agreeing with you that a little silicone would do the trick.

He didn't say which kind of drain he uses, with weep-holes -- but that maybe is not serious. However, not once did he complete your questions with a small sentence to say water seeping through the grout goes down onto the membrane and slides towards the Weepholes and leaves your house.

I wouldn't trust him to do a good job, based on that conversation. Even if he did use the right drain, he might block the weepholes. Either through ignorance or laziness.

In a certain kind of well-ventilated "leaky" house, his showers might last for many years and not cause moisture and mold in the walls. But those remarks about silicone are killers. If he thinks a little silicone is going to help "waterproof" walls, his sense of what works is not good to begin with. He shouldn't have given you those easy answers.

Even if he agrees to put poly up, he might not put it up with care. There aren't many people who like being corrected and shown what is wrong. Certainly not among tradesmen who have their pride to protect. After all, he was recommended to you and he knows it. He is not likely to want to know how to improve his methods. My assessment.

Here is a link that might be useful: Harry Dunbar Ontario Tile


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RE: Other Moisture Barriers Besides Kerdi for Shower

Hi David,

You are correct. It was quite clear to me during our conversation that he puts up the cement board and places silicone caulk on the seams of the cement board sections. He also caulks any cracks. Nothing else goes up on the walls. There was no mention (even though I asked without trying to "lead" him), of tar paper or any other type of waterproofing or drainage membrane on the wall frames as everyone has mentioned. I also had read up on Harry Dunbar link that Mongo supplied.

It appears from his answers to my questions was that his initial "sand mix" goes down and then the membrane, then more sand mix sloped. I could not get him to say that initial sand mix was sloped and it sounded like it probably went down flat (as all of you have said should not happen), then the sand mix pre-sloped on top of the membrane.

David you hit on my other concern, even if I mention wanting something done differently, i.e. some type of membrane over framing before cement board or membrane after pre-slope, I would still wonder if it was correctly installed .

Any of you experts available in the Texas area? LOL


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RE: Other Moisture Barriers Besides Kerdi for Shower

It doesn't seem like your guy is deceptive, he just comes across as being uneducated.

He's probably referring to "Aqua Tough" instead of "Aqua Touch". Aqua Tough is not a cement board. It's a derivative of gypsum and fiber cellulose. Even though USG recommends it for tub and shower surrounds, personally I would not use it in a shower. But that's my personal opinion. Nothing more.

I've already discussed why cement board is not waterproof in my previous posts.

His shower pan description sounds fine. "Sand mix" is fine.

Using silicone on the walls? A waste of time. My opinion. All he needs to do is use 6-mil polyethylene plastic sheeting on the walls before hanging the cement board. Have the bottom edge of the poly drape OVER the part of the floor membrane that goes 10" up the wall. The cost of the polyethylene is pennies, it will be less than the cost of the silicone and it'll actually provide protection.

The cement board seams? Those should be taped with alaklai-resistant mesh tape and then thinsetted. The reason the seams should be taped and thinsetted is to make the wall assembly that is made up of several individual pieces of cement board perform as a singular monolithic surface. Seams that are not taped and thinsetted could cause cracking in the tile and grout over the seams. The silicone does pretty much nothing.

If he resists, hire someone else. My opinion.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Thank you so much Mongo. Wonderful points. I know on a couple of things you've said "Just my opinion," but I would like to know why you would not use Aqua Tough?

I understand it is your opinion, but I value your opinion and all the other experts/professionals on this site. In my field, an informed consent (will use informed opinion here), is one that weighs pros, cons, other information and that person can then make their own determination based on this input.

Being my wordy self...as usual...I would like your opinion on Aqua Tough and why you don't use it.

Thanks again for your time.


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RE: Other Moisture Barriers Besides Kerdi for Shower

The structural integrity of plain old gypsum board can be destroyed by exposure to moisture.

A manufacturer can combine gypsum with other additives that promote water resistance or waterproofing. Or they might apply a water resistant or water proof skin over a gypsum core.

Basic testing is done and the product passes whatever tests it passes, it's the new miracle product that keeps the manufacturers gypsum plant rolling along. They've maintained market share for a couple of more years.

The product may perform well over the long term, or it may turn out to be an abomination like good old "green board" or moisture resistant drywall, that was touted as a tile backer in wet areas for years, even after it showed signs of failure in application.

Aqua Tough may perform fine for decades. Or it may not.

Cement board like Wonderboard and Durock has been performing fine for decades.

I'm not trying to disparage the Aqua Tough product or the manufacturer. "My opinion" is that there are other products out there that work well, are proven performers over decades of use, and in my opinion, are not a gamble. They are knowns that have been known for decades.

Cheaper? I'm willing to spend $11 more per shower built for materials. Lighter? I'm willing to carry an extra 18 pounds of the heavier material up a flight of stairs.

Lighter and less expensive doesn't mean better. Nor does heavier and more expensive guarantee better performance. Nor does the newest technology always trump the old.

I simply try to choose the better and more reliable product for the application at hand and I don't fret over a couple of dollars or a couple of extra pounds.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Thank you Mongo for the explanation. It came just in time. I just had two other tile guys come in today and YOU WILL NOT BELILEVE...okay you pros out there probably will believe...what I heard today.

When I mentioned what the original installer said, I think David you called it laziness, Mongo you called it uneducated. Here's what I found out.

I had two additional tile installers out today. I was still not hearing what I wanted to hear when I asked for details about their process, esp. regarding the moisture barriers behind the cement board and the membrane on the shower pan floor. The last guy seemed very knowledgeable and I said to myself, I've got to come on out and just point blank ask because I am not getting anywhere.

He said the same thing about cement board as the previous guy, but at least HE mentioned, taping those seams of the cement board with a mesh strip and thin setting it. So far so good. I asked about some other moisture barrier for the framing before cement board. He said they use a poly liner thing behind the cement board on the exterior wall. They don't normally do it on any other wall but they could... no problem. He mentioned some of the new boards that are lighter and made of foam, but he said they don't use them. Same deal, unproven and he would prefer cement in his own home.

We talked about the shower pan membrane and he too talked about sand mix, membrane, build slope and tile. I finally came out and said, "I read somewhere the membrane should be put on a slope or something." He said we generally do it flat but what you are talking about is the pre-slope. He KNEW ALL ABOUT IT! What he said next floored me. He said yes in the Highland Park area we do a preslope. They have million dollar homes there. Not to say your house is not nice, but that area has more restrictions. Mongo, David and Bill...he described the steps just like you said...I guess my less than million dollar house didn't warrant the "correct" installation technique. :-( He even said why it is better to put it on the preslope, but I guess "cheap" houses don't get the extra steps. LOL

I asked him about the membrane placement and he described what I had seen in the Harry Dunbar website. He did say he goes up about 8" on the walls, not 12 inches. He did say doing the preslope would make the shower pan area higher, but I told him I did not have a problem with that as long as the membrane was on the preslope. He did not have any problem doing it, but I am sure it will be reflected in the estimate he gives me. :-(

Thought you guys would be interested in what I found out today. Thank you so much. I definitely will not be using the first guy.


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RE: Other Moisture Barriers Besides Kerdi for Shower

yes, there are many more reasons to avoid using this installer.

Sonepi if your quotes are accurate, then he said he slopes only after the membrane is laid down, instead of presloping. That is a major concern.

A minor concern is that he used "waterproof" to describe something that is water-resistant. It has long been known that gypsum boards can be made water-resistant but that this is NOT good enough for a shower wall. Reading usg.com site, I see "Unlike traditional water-resistant gypsum board, FIBEROCK Aqua-Tough tile backerboard..." which makes it sound like it is different from traditional water-resistant gypsum board. No it isn't, as the sentence finishes with : "...derives both strength and water-resistance from its uniform composition." In other words, it too is just another gypsum board that RESISTS falling apart when soaked. It also remains rigid when mold grows in it, so it is "mold-resistant". It will not crumble or turn to mush, when moist, while it will be contributing actively to make your house rot because gypsum boards hold moisture more than cement boards do.

hth


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RE: 2 Other Moisture Barriers Besides Kerdi for Shower

My remarks were about the first installer.
Your new post came in 5 minutes before but i had not yet gotten it.


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RE: Other Moisture Barriers Besides Kerdi for Shower

Totally agree with you David. My first instinct when talking to the first installer was something he said seemed off. I have taken him off my list. He did like the word waterproof though. LOL.

The last installer, I am going to consider. I'll check references and look at his work. He knew what and how to do the job, he just did not routinely do it that way. He did not seem to have a problem doing it the way the "rich folk" have it done. ;-) We'll just have to see what happens and if I will have to pay "rich folk" pricing to get the job done correctly. ;-)


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RE: Other Moisture Barriers Besides Kerdi for Shower

Hi sonepi,

Would you share about where you are now with this? What was the estimate like from the third guy doing it the "rich person" way?

I've learned so much simply reading your thread here. :-)


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Nobel Membrane is not Kerdi

Nobel Company makes a membrane that looks just like Kerdi I believe - it is even almost the same colour.

Christopher from Wrightworks LLC is building a nice Quick Drain USA Channel drain shower installation and they used Nobels membrane up the wall and on the shower floor. I'll try and get Chris to post his work here or get him permission for me to share his pictures. Here is another top online gentleman that most of you will not know. Check out his work - he is one of the top builders in the USA.

Kerdi is but one option. The new Kerdi Board I believe only has WEDI as competition...


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RE: Other Moisture Barriers Besides Kerdi for Shower

Nobel Company makes a membrane that looks just like Kerdi I believe - it is even almost the same colour.

If I'm not mistaken, that's Noble CS, which is a crack suppression membrane, not made for waterproofing showers. It's actually a thicker sheeting.


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Nobel's Orange Coloured Membrane for showers

Hey Bill.

I spoke with Nelson at Nobel today and inquired about this Kerdi Twin. It turns out it is the same product as the Blue Nobel membrane but a different die lot for Dal Tile outlets.

I wondered the same when I saw Chris's pictures. Dal Tile does not stock it here so I called head Office to get a roll. "Square Pusher" is pitching a new Quick Drain installation and I am going to install this first one for him if he gets the job. I ordered a 5'x100' roll - that should keep me and Peter busy...

Nelson mentioned that the release of their new drain is still a week or so away and I asked him to send one to Paul in Huston for a second opinion (other than mine). I look forward to Paul's report and getting these 2 new channel drains....

Love it!


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Nobel Membrane sales in North America

Who is installing with Nobel Membrane on a regular basis?

The product was hard to track down locally and in the end I went straight to the head office and they got their local man out in my parts to come by and show me the new Nobel Drain (well half of it) and pick up my deposit on the 100 foot roll I ordered.

Not much help to most of you but if you need Nobel - I'm packing in about 2 weeks...


 o Post a Follow-Up

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