Installing cement board behind my shower

http://youtu.be/t2PvdnwcqB4

Here is a good way of marking the water level in a flood test.

Quote:

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Originally Posted by jadnashua

...Since most places require a water test, this discussion is kind of mute...

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Finally we agree on something. So at least now I know you actually know the proper procedure and we can move forward.

Quote:

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Originally Posted by jadnashua

and, the guys over there regularly tell people to get a permit and inspection...

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And then the BS shows up again. In fact over 'there' I have never seen any of your "Kerdi Boys" recommend to anyone to have a flood test done. In fact in almost three years not once have I seen it. Can you post a link to say two posts where you have noticed this? I'll hold my breath while you dig that info up.

But I'm happy you finally omitted that 'Most Places' (Canada & USA) require these flood tests. It most be that silly code that says all shower pans need to be built so they hold water. I might be just fishing here - but I think a flood test proves this. Imagine that - filling a shower pan to see if it in fact can do the job it's required to do.

You know what would be fun? If someone reading this back and forth bander (thinking we are a couple of school kids debating) just tries there own experiment and goes over to the John Bridge Forum and starts a new discussion called "Should I flood test my shower project?". Then sit back and watch how the posters have a field day. How many will say "Yes - It is required by code" and how many will say "I use Kerdi every month and if you use a sheet membrane it is kind of overkill". I know where my money is.

Flood test are not useless Jim - they are a code required step in shower construction. And of course you would protect them after doing them, although that is not written into the code books but just good old common sense.

"flood test" got hits on 280 threads over there in the DIY'er section. Building permits are often mentioned. I get nothing from any site I participate in except a way to keep my brain agile. Anyway, enough of this...I think we actually agree on more than we disagree on, and it's not pertinent to this thread.

Quote:

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Originally Posted by jadnashua

"flood test" got hits on 280 threads over there in the DIY'er section. Building permits are often mentioned. I get nothing from any site I participate in except a way to keep my brain agile. Anyway, enough of this...I think we actually agree on more than we disagree on, and it's not pertinent to this thread.

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I just goggled it Jim.

Here is the top hit on Goggle; http://www.johnbridge.com/vbulletin/...ad.php?t=83421 Aren't they your Kerdi Boys? I see CX replied. so did Davy, Jeff, Paul, & Brian

http://www.johnbridge.com/vbulletin/...ad.php?t=86562 Here one of the top Kerdi Men talks about how Kerdi can tear if your careless.

Found this quote of yours when someone had Kerdi Wicking issues.

From the picture, it appears you didn't get great adhesion of the thinset to the Kerdi. IF so, that is the reason it wicked as much as you've seen. It looks like there are bright orange and duller orange (and more bright) on the bottom sheet. If your thinset was too dry or you didn't embed it well, it is hard to get great adhesion and the full waterproofing at the seams, and your Kerdi isn't embedded as well as it should be. Normally, if it is done as good as it can be with full contact, it won't wick more than 1/4" or so. You're still probably okay...see what the pros think.
__________________
Jim DeBruycker
Longtime lurker, avid DIY'er

http://www.johnbridge.com/vbulletin/...ad.php?t=80396

That was in 2010 Jim.

Reading through these posts most references to Kerdi Flood Test are regular posters saying ya I flood test my showers but not actually anyone recommending it get done.

I love that on the John Bridge forum you comment on wicking and talk about poor adhesion. It is so easy to make a mistake. This is why you flood test showers.

JW

John, why don't you give it a rest already...?

What does your problem with the JohnBridge Forum have to do with this thread?

Quote:

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Originally Posted by dlarrivee

John, why don't you give it a rest already...?

What does your problem with the JohnBridge Forum have to do with this thread?

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In this thread while discussing the use of cement board we get a post of "I just use drywall and Kerdi". There is such a un fairly weighted scale offering up garbage advice. Our man Jim here aids in this online discussing pin holes and one sided opinions. If we could stop Jim from sending people away that would be a start. Sending people their does more harm than good in my opinion. Why don't you ask Jim to stop this practice?

The original question was I believe about vapour barrier and where to instal the cement board.

This is a good question and the use of liquid waterproofing can help greatly here. So could not screwing through the tub flange. So could solid blocking around the tubs tile flange. And a number of other points.

I agree I get off topic at times but this is only because I'm trying to save people from making mistakes and trying to slow the funnelling effect we have here on Terry's site down.

I write a lot on Contractor Talk and there are many tile men who have debated with me over the past few years. Most of the regulars there did like I asked or recommended and double checked with their local Schluter reps and Schluter head office and found that much on the install procedure they thought was correct was in fact wrong. Many have switched to the use of Hyro Ban, Aqua Defence and Noble Seal TS. It is rare to see a Kerdi Shower anymore there.

Online researchers need the facts. I'm trying to give them to them.

I do not see any harm in that.

http://i839.photobucket.com/albums/z...Fixforatub.jpg

Here is a look at cement board in a shower. The cement board was installed just above the tub flange and then I used liquid waterproofing from Hydro Ban to cover the cement board and to fill in a little the gap between the tub's tile flange and the bottom of the cement board. There was a solid blocking course around this tub.



http://i839.photobucket.com/albums/z...connection.jpg


After my Hydro Ban was finished I used a little Kerdi Fix to fill the reaming gap. Sealing the bottom of the cement board to the tub tile flange. This tub's waterproofing will not allow water to escape behind the backer board.

Many tubs are installed without the solid blocking course. This can cause deflection between the wall studs and lead to a failure point.

We have a new project in North Vancouver and the tubs are all going in. I'll snap a few pictures and outline this procedure better.

John Bridge sends people here for plumbing questions, and I send them there for tiling questions...I don't get paid, just like there are more plumbers that deal here, more tilers congregate there. They push people to follow the TCNA guidelines, which is the bible on how to do things tiled. WHile here, you may get one or two opinions on a tiled situation, there you may get 10, and in an hour verses a day or more. So, it behooves everyone to filter out the junk, but there are enough reviews so that if there's an error, it gets fixed pretty quickly.

And, in the examples you quoted, the problems were discovered during a flood test, and my explanation was why it occured - nobody was saying don't flood test. One reason Schluter specifies a minimum of a 2" overlap is to account for some errors...a properly done seam shouldn't wick more than 1/4-1/2", and if you have at least 2", it is still safe even if it wicks some as the result of marginal installation practices which may occur with a first-timer. There is generally little standing water, especially for 24-hours, so as long as it doesn't wick beyond the seam, it's still perfectly safe.

In one class, they had Kerdied a cardboard box...this one had been in use for about 6-months and was getting kind of floppy, but it was filled with ice and drinks everyday, and by the end was mostly water....the cardboard was fine except from the flexing was no longer stiff. But, the Kerdi was still intact and bonded. The stuff works...other stuff works. Just like I drive a BMW, you may prefer an Audi...they're both good.

The old Kerdi Drink box example. I love that.

I have made them with Hydro Ban, Red Guard and Aqua Defence in my shop. We check all new buckets with this testing procedure. I have grown fish food in these test boxes and then feed them to my fish (mosiquito larva).

Jim your an excellent salesman and a strong supporter for Kerdi. Thank you for agreeing that all showers need to be flood tested. Please remind people in your posts.

JW

Remind me next time I ask, to always find one of JW's showers to go swimming in.

As far as non-swimming showers, I'll stick with Kerdi properly lapped (done as roofing is done, horizontally with overlap, not with band), and never once be concerned that it will leak... unless of course I decide to plug up the drain and try to go swimming in my 4" deep shower-pool. Even then, I don't have any concern that it will leak, but its a moot point, as this is not a real world situation.

John knows his stuff and has his opinion. There are many other professionals who have a different opinion. Pretty much all of these waterproofing methods are valid when installed properly, so just install them properly.

You'll probably note here that I'm the one who said to install kerdi on drywall (per manufacturers instructions), and that I just use VersaBond (knowing full well that this will void the warranty). If you're not comfortable with doing that, don't. Simple as that. I'm comfortable with the performance given using this method, and with voiding the warranty.

John, a little more tact would be appreciated. You can feel free to express your opinions, but you don't have to be an ass about it. I'm offended on Jim's behalf the way you've responded to him. I respect your knowledge and input on showers, as you clearly know a lot about it. I'd respect your comments a lot more if they were a bit more polite. You don't have to back off on your beliefs at all to state them firmly and with respect to others. Thanks.

Quote:

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Originally Posted by mtcummins

... I'd respect your comments a lot more if they were a bit more polite. You don't have to back off on your beliefs at all to state them firmly and with respect to others. Thanks.

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Polite? Respect? What does this have to do with trying to outline proper shower construction?

I appreciate your disclaimer that your method of construction is not per the manufacture's guidelines. At least you spell it out. Would you share you company name with us? Do your clients in Pittsburgh PA know that you are deviating from the manufactures guidelines? I would bet that if given the choice any one of your clients would want you to follow all the manufactures guidelines and I would further bet that if I called your local building department they would tell me that you are skipping a code required step.

I'm guessing that these flood test are not convient for your scheduling as it is hard to book and fill up a week. I get that. But. You are building showers with no safety measures in place and that is wrong. Sorry if this hurts your feelings or you think I'm being mean or have no tact. I'm a tradesman not a politician.

Facts are facts.

I wonder how many plumbers here skip a flood test. I bet very few. But when a tile man does this step all of a sudden it is an option. I would guess you install these Kerdi drains as well. Are you a ticketed plumber? Plumber's install drains. Tile men set tile and waterproof - it's a team effort.

Your use of drywall is crazy - no offense. Spec'd by Schluter or not it is probably the worst way to construct a shower. This door is closing on this practice - that you can bet on. And if you live in Vancouver it flat out is not allowed. No no no.

I do have strong opinions. I think most of the work build out there is crap. I find most trades just don't give a $%^* and it shows in the performance of these showers. I find that box store advice is like the blind leading the blind and I have been working week after week for almost three years to make a small dent in this miss information and marketing maddness.

The more people research this point, the more people who double check facts the better chance they have of getting a properly built shower. An average bathroom renovation is in the $7,000 - $ 37,000 price point. A tile man might bill between $ 700 - $ 4,000 on a average project so for the convience of "ONE TRADESMAN" you are going to risk a failure that can make your kids sick, harm your home or worse put your life in danger! Crazy Talk.

Hire a pro. Spec that all guidelines are followed. Flood test the work. Easy as pie.

If you do it yourself. Meet your building inspectors. Research the facts. Call the suppliers. Call the manufactures. Study. Double Check. Triple check the facts.

Who is right? Me - I know I am. Jim - Sometimes. You - not even close.

Sorry. I'll work on my tact in the future.

Mtcummins I would appreciate it if you would share your company name with us so people researching showers in Pittsburgh can decide to call or not call you passed on their acceptance of showers constructed outside of the norm. I would appreciate it if you could in the future flood test your work so you can do your part to reduce possible watse in out land fills.

Jim's a grown man and chooses to market Kerdi and promote John Bridge's web site. The John Bridge tile forum chooses to promote the use of Kerdi and in doing so lets the manufacture's guidelines go by the way side ( I think) on most cases. They don't come out and state it it is done more in a soft sell scenerio. "A little birdy told me...." "I know your not suppose to, but ...." "and on and on..."

I'll let my work not my words speak for them self. Any homeowner researching shower construction should always confirm the facts they read online. Call the manufuactures and always in your agreement with subtrades insist that all printed guidelines be followed. Just read a code book or speak to a city inspector - these are the rules and people that make the calls - not some guy from Vancouver or Pittsburgh who says it's OK to do it like this.

JW

Ha, this extreme idea of safety reminds me of the discussion on putting GFCIs on refrigerators. Why is it that specific trade people think that every little minute detail of their trade is a life or death issue? Is this just protectionism? Fear of the DIYers taking their work away? Can we really not be reasonable in our discussions about what is truly important vs what isn't? I have a news flash, if this is how you view your work... not everything you do is all that important in the grand scheme of things. I doubt many plumbers in here would have an actual problem with a tiler setting a kerdi drain, if they're experienced with PVC/ABS connections. Maybe some will say otherwise, as it is prudent to protect their businesses. But really, its not rocket science to make one connection, and its a connection that under 99% of circumstances could be made with a shoestring (no cement) and not leak. With the exception of course being when you plug up the drain and go bobbing for apples in your shower stall. That said, if you just asked why concrete has anything to do with plumbing... put the kerdi drain down and go call a plumber... right now.

I get that you're doing things by your prescribed code. I also get that there are probably less than 100 bathroom remodels in Pittsburgh that cost $20,000. Prolly hard to believe in Vancouver, but here you can buy a decent house for about double your high end bathroom remodel number. And that's in a decent neighborhood. Most people quite simply do not spend this kind of money on remodels here.

That said, if you can find someone willing to waterproof anything, you're doing well. Try to sell them on this, and you better have thick skin. Most of the stuff I take out isn't waterproofed at all, if I'm lucky its tile on cmu, often its tile on gyp board that's rotted all to hell, moldy, etc. I waterproof b/c I think its important to do so, even when I could get away with just doing cmu and tile in a tub surround. I don't flood test b/c I don't think its necessary with membranes, as if you know how to install them and are careful around them, you know if its going to leak or not. I would flood test a liquid system, if I chose to use one.

I won't share my company info, but I'm not looking for any work, so no worries to any of you out there looking to build indoor goldfish ponds. I won't risk your whole family's lives by building a shower in your home. I have a set of regular clients I work for on occasion, and I do work for my own property. I'll be the one who has to fix all my showers that are in imminent danger of leaking any second now.

The shower stalls I install for most of my clients are not tiled. They're not that type of clients. Those showers tend to be Vikrell units of 1-4 pieces, and don't require most of this work, just good straight stud walls, sturdy level floors, and proper assembly of parts. I sometimes, though not too often, build a shower in one of my own properties, and the kerdi system works great for this. Most of these installs are still tubs with a tile surround though, so there's no pan to flood test.

I'm not sure how respect and proper shower construction are mutually exclusive. If you want to make a dent in people's perceptions (that are definitely more often than not led astray by HD types, I agree), you won't do half as good a job with a sledgehammer over people's heads (they tend to resent that a bit, it turns out, and the information just leaks right on out of their smashed in skulls (perhaps they needed flood tests on their brain-leak waterpoofing before sledgehammering?)) as you will with polite instruction. Its that hole attracting bees with honey thing...

So your saying that in your town waterproofing a shower is too expensive yet you build them with a $130.00 Kerdi Drain and Kerdi which sells for about $3.00 per square foot. An average shower is say for arguments sake 3'x4'. With bring the waterproofing up 6' you have a total of 72 square feet of membrane needed - give or take.

72 x $3.00 = $216.00
One Drain = $ 130.00

Now setting a Kerdi Drain you need at least 3/4" of mortar under the drain but 1 1/4" to 1 1/2" is advised. So if the shower pan is 3'x4' with a center drain that makes a total volume of the shower pan at 18 cubic feet. A 40 pound mix of 4-1 (sand and cement) will net about 3.5 cubic feet. So 18 cubic feet by 3.5 = a hair more than 5

5 Bags of clean sand = $25.00
1 Bag of cement = $15.00
1 3'x5' sheet of expanded metal lath. = $15.00
1 section of 30 minute building paper = $5.00
1 Bag of thinset = $15.00

So to build a Kerdi shower and waterproof the walls your looking at an investment of roughly $421.00 excluding install charges.

If your local town's clients do not want to build a waterproofed shower perhaps a good old compression drain and liner is the way to go.


5 Bags of clean sand = $25.00
1 Bag of cement = $15.00
1 3'x5' sheet of expanded metal lath. = $15.00
1 section of 30 minute building paper = $5.00
1 Bag of thinset = $15.00
Clamping Drain = $17.00
Liner = $40.00
Glue = $10.00

$142.00 total cost. Now this a lot lower than the Kerdi Shower and both if built right will pass a flood test. But this shower has no pre-slope. Add in a Noble Pre-slope for $45.00 and your total cost is $187.00 under half the cost of the Kerdi Shower.

What if your in a rush and all this waterproofing is "Hog Wash"? It's not but lets say you want it fast and cheap.

Have your plumber come and set the drain and liner day one and fill with water - he might as well install that new shower head and fixture while he is there. Your plumber can do this all in a day easy.

Have your tile guy come in and set up day two. He can protect the shower pan and start the wall boarding. Near the end of this second day your tile guy can drain the shower test and set a slope with Mapecum and by morning he is tiling. This system is faster than a Kerdi system and half the price. A good tile guy will protect the weep holes from plugging and here again Noble makes a great weep hole protector for about $5.00. Some pea gravel or candle wick will also work.

It's knowledge and a understanding of the different building materials that can built fast cheap shower that work as well as any high end unit. You need not have to deal with a leaky moldy mess just because you can't afford the fancier materials.

It's marketing and time lines that have led to this confusion over proper shower construction.

In an effort to make more money or save more time people skip steps. If enough people do this it becomes common place. No need for it.

If your a builder ask your old crew these questions. Question their building practice. Ask them to raise their game.

As a home owner remember it is your house and it is well within your right to get a code approved, flood test, damp proofed shower. If you crew can not deliver it you should at least acknowledge that your settling for less. I bet most clients are never informed and are blind to the fact that their new shower is leaking from day one.

JW

Wow, some lucky company saw a sucker coming to get you to pay that for kerdi products. I pay nowhere near that. I'd be a kerdi hater at that pricing too. And I don't do mud beds with kerdi, they're unnecessary. So all of your pricing info is way off the reality I live in.

But, thats pretty much beside the point... if you actually read my post, I said I don't install these for clients. I install these for my own projects/properties, and I spend the extra money to waterproof it right b/c I feel its the right thing to do. I actually spent more than your number on my most recent kerdi shower (in my master bath), which was larger and had niches, a bench, etc, so it took a good bit of product to seal it up right.

"I bet most clients are never informed and are blind to the fact that their new shower is leaking from day one." Wow, this is a bold statement based on nothing. Once again, a moot point b/c I don't put these in clients homes, or at least haven't to date. But assuming I did, you're still making an awful lot of assumptions to make a ridiculous claim like this.

Build your showers your way. I'm sure they're done well and that's fine. I have no interest in "converting" you to kerdi, or telling anyone else out there that likes hydroban or noble or whatever they like that kerdi is better than what they use. For those people who want to do their own shower installs (which is what this forum is mostly about), Kerdi is a great product and does its job well. If you're halfway decent with thinset, you can make an extremely well made shower w/o some of the hassles that those of you who are pros at this do (such as creating a mud bed). If you don't like it, don't use it. But don't come on here telling people that its junk when you don't even explain how to properly build a shower using kerdi's system... you've just used kerdi in place of your waterproofing methods and ignored the rest of the system. Then you make claims about improper installations and such and such.

For those of you looking at Kerdi, don't let JW scare you away with this crap. I agree with him on some things, do your homework, research the different options. Choose one of his methods if you're comfortable with that. Install them to manufacturers specs for your peace of mind, and know that whether you choose Kerdi or Noble, or most of the liquid systems, you'll have a great shower if you install them correctly. Do the flood test if it makes you happy - I'm not opposed to it, just find it unnecessary if you know how to properly install a membrane shower system.

I'm done with this conversation, its clear that its going nowhere. Say what you will, I've said my piece and I'm not responding anymore.

Don't go now. We have just started the debate.

I'm not scaring anyone away from Kerdi just making sure they flood test their work. Remember Kerdi is the thinest waterproofing on the market to my knowledge. Can you think of anything thinner?

Thin makes things easy for build up in corners (but with simple forethought this is a non issue) - this is true but also makes it so easy to tear. Easy to pop a hole in with a screw or dropped tool.

Quote:

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Originally Posted by mtcummins

Wow, some lucky company saw a sucker coming to get you to pay that for kerdi products. I pay nowhere near that. I'd be a kerdi hater at that pricing too. And I don't do mud beds with kerdi, they're unnecessary. So all of your pricing info is way off the reality I live in...

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The prices are quoted are retail prices in Home Depot and Rona. With my trades discount I can get the Kerdi drain for $92.00 (if I buy ten at once). Kerdi can be sold for as little as $2.10 square foot but this is buying massive rolls. You must buy the Kerdi Shower kits. Here in Vancouver they retail for over $600.00.

The main point of this discussion is to flood test projects and build proper showers - not what the price of Kerdi is in North America. Your stand I think is you only build them right for your own personal projects but not for everyday clients. I don't see the logic there at all.

We can agree that any waterproofing material can build a code approved shower. This is for sure and I use multiple products here in vancouver and show them all off. Kerdi is the one product I care the least for and to review this is because they don't allow modified thin sets over top and it's just 8mill thick roughly 1/3 the thickness of a credit card.

Build your shower anyway you like and to check your work or to check the work of the installer insist it get flood tested. Do you really want to "Trust" your installer that he did it right. That the thinset was fresh. That the liquid didn't freeze. That the floor was sound.

Or

Do you want to see first hand that the work you did or paid to have done in fact does it's job.

Here is what a flood test sounds like when finished.

http://www.youtube.com/watch?v=9Oi1mNht7Lk

I used Mapei Aqua Defence on this project.

http://www.youtube.com/watch?v=9Oi1mNht7Lk

Quote:

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Originally Posted by johnfrwhipple

John Bridge only used Kerdi I believe for perhaps 8 years and then retired. I believe I flood tested more showers last month than John Bridge did in his entire career. I believe he commented on one of his Kerdi threads that he did it once or twice and then felt it was no longer necessary. I find it odd that such a well respected tile forum does not promote flood inspections. If you look into this Jim you will I believe find one example of a John Bridge flood test. It's that crazy shower built with a couple of 2"x6"'s for a curb.

I do not think I have built more shower's than Mr. Bridge. I do feel that his acceptance to installation guidelines that differ from the manufactures recommendations is wrong. I also feel that Schluter's position of not correcting it is wrong. I also think that most of the posters on the John Bridge forum are made by people who actually don't even build showers for a living.

I think people should build proper showers. I think people should install mortar and waterproofing products as directed by the manufactures. I think all drains should be installed by plumbers not tile men.

Like you said Jim we are all individuals and we all have our own opinions. I want to see a reduction in land fill waste. So many showers fail because of poor construction. failures do to installer error. This is why we flood test showers in permitted projects and all new construction.

Everyone online should research the facts.

I offer up only my expeirence and share my successes here in Vancouver. I would love to see a few Kerdi flood tests. Perhaps Jim you can post a few of yours?

I would also like to see Shark Bite fittings taken off the shelves and sold only to plumbers. I would like to see all residential water lines pressure tested. I would like to see all drain and vent lines flooded. But there is only so much time to type. So I monitor the waterproofing side of the internet.

Jim your good friend of Mr. Bridge I'm sure. Maybe you can ask him to promote flood test on his forum for me? Maybe you can start a thread and promote them. I have never read any post of yours where you recommend someone to preform them? I do read post after post - year after year your postings on how easy Kerdi is to install.

Help me out Jim. Get the boys on the John Bridge forum to recommend flood tests. Think about how much waste can be saved from these dump sites.

As far as tech support that is easy. If you want tech info from Noble call their 1 800 line ask for Richard or Eric - tell them John from Vancouver says Hi.

If you need help from Laticrete call Anita - she is a sweet heart and will get the right tech.

Mapei ask for Shawn.

No need to type just call. It's free and these people work for the manufactures and can advice you or anyone the proper install techniques.

Here is the contact numbers for my three favourite suppliers;

Mapei 1-800-361-9309 (Canada) or 1-800-992-6273 (U.S. and Puerto Rico)
Laticrete 1 (800) 243 - 4788
Noble Company : 1 (800) 878-5788

For proper Schluter System install instructions call;

USA 1 (800) 472-4588
Canada 1 (800) 667-8746 ask for Courtney

Online facts should always be confirmed by the manfacture. Check with your manufacture's local rep and always follow the printed instructions.


JW

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I think that John you need to go to a Schluter training session to understand their products, especially Kerdi. And go to the CTEF to see the water chest made with a cardboard box with Kerdi lining which has been going strong for about 6 years as an ice chest. Thickness of the Kerdi has nothing to do with it's waterproofing capabilities.

J Whipple has good points. He makes it clear when he hammers his point home.

Over the last year I have seen John Whipple's posts honing in on several weaknesses in both Kerdi AND in the JB forum's systemic bias preventing the alternatives to Kerdi from being considered as reasonable. John Whipple is articulate.

All they do at the JB forum is to raise doubt about the alternatives to Kerdi. I find Jim Jadnashua to be a repeater for the same talk; no matter how much he may be all nice and well-intentioned, he is doing harm by defending Kerdi in multiple posts and not building one Redgard shower. not looking at the fact that there are millions of showers built with good product. The internet has places where people say the orange one is "so" good, and jadnashua is a repeater.

I saw a box made of Hardiboard. It was sealed with a glass top. It held water. The people demonstrating Hardiboard used this box to sell the idea that the Hardiboard could be used for shower walls. That was about 10 years ago. Since then I've learned not to be impressed by the water box trick. About 7 years ago in fact at the JB site, senior people wrote that the water box trick (for Hardiboard) was a sham trick. It doesn't prove watertightness, apparently, because the wicking and pressure are different when built in, not a box you carry around from one demonstration class to another.

The Hardi people never said one had to seal Hardiboard. So they implied their product was good enough for shower walls, without any membrane. Back in those days one could staple a sheet of poly to it, on the outside side. But staples = leaks. But between you and me, we all know that walls are not critical areas; floors are. But why build a box and show that water didn't evaporate through Hardibacker? Why? What they accomplished, after the initial GOOD impression, was to make me doubt them since they were implying it was waterproof. Schluter is similar: they engage in indirect marketing by hiring the JB forum to spread misinformation and fear about all their competitors' products. Bad boys. Jim Jadnashua, give this some thought. John Whipple has made good points.


Hope this helps.