Layout lines on Ditra

[Jadnashua]

The ones which require ONLY NON MODIFIED.

And, as you know, if you really want to use a modified, Schluter will allow you to with prior approval and IF you use a rapid set mortar. A rapid set mortar does not use latex type modifiers that need to dry, so in that case, cures in a known, reliable timeframe.

There are valid technical reasons to avoid a modified thinset over any waterproof surface bonded membrane - drying time, as recognized in the TCNA handbook says, and I quote:

When latex/polymer modified Portland cement mortar is used to install ceramic, glass, and natural stone tile in an area that my not thoroughly dry out in use (e.g., swimming pools and gang shower, etc.) or where initial drying is inhibited (between tile and an impervious substrates), it is recommended that installation be allowed to dry out thoroughly before exposure to water. This drying period can range from 14 to more than 60-days depending upon the temperature and humidity and other climatic conditions, and whether the installation is interior or exterior...​

Schluter, being conservative, specs an unmodified, that they know will reach maximum strength in a known timeframe. When I lived in Jordan, I was able to tour some ruins from BC Roman structures that had sections of floor installed with some glass that were still intact...no modified thinset around then...between a waterproof membrane and an impervious tile is the best possible bond for those types of tile and a dryset mortar. Now, if you can afford to wait, and want to follow the guidelines, do you really want to tell the customer - hey, the shower is finished, but you shouldn't use it for two months!

Will a failure occur, probably not. Will it be as strong as it should be? Not if you don't let the modifiers dry out first. Will you have a failure, probably not. The stuff is just that much overkill. Might you have problems trying the same thing over something like cbu? Yes - modified has its place, and bonding high density tile to a rigid surface or wood is the best use of the stuff.

So, the guideline is not a Schluter thing...it is a TCNA guidelines thing and experience over lots of years and research of the product - a dryset is a known entity...a modified throws you a curve. It's not that the other membranes are really different, it is the intolerance for potential failure and knowing your product and standing up for it in the face of opposition.

Just how long do you think a monster tile like a 48x48 on an accessible shower with a linear shower drain over a waterproof membrane will take to dry out the modifiers? probably a lot longer than the time listed above. And, some of them are barely 1/8" thick...with soft mortar underneath for several months...

 

[Eurob]

And, as you know, if you really want to use a modified, Schluter will allow you to with prior approval and IF you use a rapid set mortar. A rapid set mortar does not use Portland cement.



Just how long do you think a monster tile like a 48x48 on an accessible shower with a linear shower drain over a waterproof membrane will take to dry out the modifiers? probably a lot longer than the time listed above. And, some of them are barely 1/8" thick...with soft mortar underneath for several months...

A rapid set mortar does not use Portland cement.

You definitely didn't read a material data sheet or just do not have a clue . And I am pretty sure those instructors -- ''S'' -- didn't tell you that either .

You should probably stop giving advice beyond a certain point .



Just how long do you think a monster tile like a 48x48 on an accessible shower with a linear shower drain over a waterproof membrane will take to dry out the modifiers?


Use Ardex or Basf products -- no need of presence of air to cure -- . And they have rapid setting mortars too , cementitious high performance adhesive .

 

[Sponsor]

 

[Jadnashua]

Okay, I stand corrected, not the first, and won't be the last, it is still listed as Portland cement...the main issue, though, is that it is configured to produce a reliable bond without requiring it to dry in hours, rather than days to months when using a conventional latex-modified mortar under the same conditions (i.e., between an impervious surface and a nearly impervious tile like porcelain, or a glass tile.

How many DIY'ers do you think can successfully use a rapid set mortar for a typical shower install, let alone trying to spread the mortar to handle a huge tile? And, still being adversarial...you can get permission to use a rapid setting mortar if you ask and maintain full warranty (but, you have to ask first). And, let's take that 48x48" tile, at say a 250psi bond with a good dryset verses a 300psi for a mid-range modified, the bond strength of the tile is about 288 TONS. Once cured, you're not going to remove it in one piece.

 

[Eurob]

So what is the big deal ? A little correction and move on , right ?

Wrong


You just don't get it . I am pretty sure ''Someone'' is paying you with word counters . Shame , shame , shame .


In Germany , the tile mechanic has the authority and responsibility of the installations . The law and the trade oblige him to do it right , not the manufacturer . The manufacturer is working closely with them , not the other way around . This translates in

Respect


You can dump whatever on a DIYer and still blame him at the end for '' wrong doing '' . DIYer have no arguments in depth about what works or not works , or knowledge of the range and characteristics of products .

Once cured, you're not going to remove it in one piece.

Imagine that . WOW WOW WOW

 

[ShowerDude]

When Jim gets out of the system he sells he gets out of his comfort zone.

Jim you claim to be here to help homeowners out, do you think all this long form pasting and quoting is helping ? or prolonging your fight to push orange products?

 

[Jadnashua]

The grass is sill green!

One weed in the lawn, and the grass is still green.

The point was and is, the mortar you use over any topical waterproofing membrane needs to make a 100% reliable bond.

The TCNA tells you that if you use a latex-modified mortar in those circumstances, you should not let it get wet until it has a chance to initially, fully dry. They also tell you that that can take 14 to more than 60 days. Last time I used a shower...it got wet when I used it, and most people will not wait potentially over two months to follow the guidelines, just like they don't always stop at stop signs, or they exceed the speed limits, or don't wear their seatbelts...usually, you get away with it, but not always.

Schluter tells you to use a dryset, because first, it does NOT need to dry to perform with their material (keeping it wet improves both the short-term and long-term bond strength). If you insist, they will also allow you to use a rapid setting mortar, again, because it does NOT need to dry to perform. Both of those materials also perform with a known, reliable timeframe. That the company was founded by a master tile setter, and is from an area that tends to follow the rules, Schluter's guidelines follow the rules, and to avoid those long delays, specify a mortar that has a known, reliable, bond in a timeframe that meets with people's expectations. The fact I had the exact reason why it worked wrong is not, or should not be the issue - recognize the forest from the trees...it's still a forest.

Until the 1950's, there was no modified thinset. Glass and porcelain tiles have been around for centuries (yes, today's porcelain is denser and more consistent, but the Chinese have been making porcelain for many centuries and it made it to Europe still centuries ago and has been used in tiling surfaces for that long).

The building techniques have changed when the tile industry wanted speed and to save money, those thick mudbeds moved to thinner, faster, cheaper, less skilled techniques. The mortar needed to change to remain reliable.

Somewhere in there, cbu came about. The industry changed. Thinset mortars, the industry changed. Modified thinset, the industry changed. Reliable waterproofing membranes, the industry changed. Engineered, thin, uncoupling membranes for the modern world (used for centuries), the industry changed. But, sometimes, the lessons learned get carried over for the wrong reasons.

The materials we have today are much more engineered than what may have even been available last year. But, the fact is, for the several decades Kerdi has been in use, you don't see thinset bond failures because people followed the manufacturer's instructions (assuming they used good technique). And, if your methods and technique were good when built, it is still waterproof and performing its job. Properly installed, you do have a THIN set installation. Very little moisture is accumulated in the structure, and it dries out quickly. It works. Now, don't follow the rules, and your results MAY differ...

If you focused on the message, and not the words, you'd see that.

 

[Eurob]

I find the technical aspect of this sort of stuff is interesting and challenging, which maybe a characteristic of having worked in a technical field all of my life. Having spent time fixing radars and missile launchers, plus writing system requirements and test procedures to ensure they work as designed, has honed an understanding of how all of the parts fit together, and what the ramifications are for doing things a certain way. This experience applies to many things in life. You can't make money, even in the defense industry, if you over build things...but, you certainly can't go the opposite way, either. After awhile, you learn when enough is enough, something some people have not appeared to understand. But, there will always b salesman and doom mongers and customers willing and able to spend money for multiple redundancies.

Why would you not relate your knowledge to related forums or industry -- specific to your trade -- ?

If I would have to choose between a Trabant or a Volvo .....or in between a Hyunday or a Mercedes .......why overbuild things ?

Why have a tiled shower when you can have a plastic one ? Hmmmmmm........ Do not over build things !

The building techniques have changed when the tile industry wanted speed and to save money, those thick mudbeds moved to thinner, faster, cheaper, less skilled techniques.

You have no clue , period .

 

[Jadnashua]

Why have a tiled shower when you can have a plastic one ? Hmmmmmm........ Do not over build things !

Everything in life is a compromise. There is a cost/benefit that can be attributed to most things. At some point, increasing the cost does not increase the benefit if that means you cannot afford it. A plastic shower, if that's all you can afford has your optimum cost/benefit. You could build your house sufficient to be able t drive a Mac truck onto the middle of the floor, but if you don't have the need, why? Most people don't have unlimited funds, and like to use them to their best advantage, thus analyze their cost/benefits relationships.

If that 'benefit' is important to you, then the cost be damned, it is a requirement, not a 'benefit'. Multiple layers of waterproofing may make you feel better, but if you applied the first one properly, only adds to the cost, not the benefit. Extra layers of plywood, may be required, depending on the requirements, but not unless there's a good reason (there often is, but that's not the point). If the structure already meets guidelines, sistering the joists may not provide enough benefit for the costs. And the list could go on forever...everything you do has a cost/benefit. Flood testing for 72+hours means the project will be two days longer than necessary. Is the cost/benefit worthwhile? To some, maybe.

So, determine your cost/benefit relationships carefully. Telling someone something is required, increasing the costs, without understanding the corresponding benefits (if there are any) is sometimes just plain wrong IMHO.

 

[Jadnashua]

It seems most pros I know don't use it or don't use it the way they are suppose too.

If you want the thinnest material on the market (that I know of anyway) then I guess Kerdi is right for you. Jim has taken three workshops to understand it completely. That's like a week of training to use one system. Scary how hard it is to use. And he is an engineer - or pretends to be a retired one.

This is so misleading and biased that it is almost comical...

People complain about material thickness buildup in corners, then complain when the material is thinner to solve that problem. Based on how much product goes out the Schluter warehouse every day, I'd have to say that there are an awful lot of people using the stuff and I know of a bunch of pros that use it almost exclusively. John, never haven taken one Schluter's 2 or 2.5-day workshops, doesn't have a clue what is covered in one of them. It covers many product lines, theory and examples of how to use some of the products, with showers only being one of them, which includes hydronic heating products, uncoupling membranes, drainage systems, profiles, and many others...the price book is like 130 pages long...there's a lot of products and the class certainly can't cover all of them, but it exposes you to what's available, and you get a chance to touch and use some of them. FWIW, actual hands-on in the workshop covers installing Kerdi, Ditra, KerdiBoard, profiles, and demonstrations of some of the other products and how to use them, like some of the better ways to cut the metal and plastic profiles, and examples of them being used. And, with that line being expanded, it is prudent to go back again to be exposed to not only the new products, but to reinforce what you may have learned previously. I went this last time to see and touch Ditra Heat, which was just introduced this February, and wasn't in the previous workshop. The first one I went to was in the 1990's, and they had introduced a lot of new materials over the years, so I went again to catch up and get the latest.

So misleading, so biased, but, that's the way John Whipple does things, anything to make himself look better. This sort of behavior is partly why he is not welcomed at more than one website on the web. One tends to attract people with similar attitudes, which may be one reason why John doesn't know many people who use the products in question. And, the big chip on his shoulder got knocked off when they asked him to be careful on how he talked about the products. It's one thing to voice an opinion, it's another thing to express false or misleading information. It's the later that anyone would object to.

If you don't like it, don't use it. But, it does what it says it will...if that doesn't meet your needs, again, don't use it. Expressing why it doesn't meet your needs is fine. Expressing that your needs are everyone else's needs is just wrong.

NobleTS, expressed as John's latest go-to membrane is a great product, but not if you're worried about buildup in a corner because it is over three times thicker, which does not make it any more waterproof just like a typical 1/8" window-glass is no more waterproof than the 1/2" plate glass window. Vapor-proof, yes, but that only becomes a major issue in a continuous use shower or steam room. They serve different purposes, but both keep the rain out. Choose based on your needs, accept the ramifications, understand your choices. What is best in one situation, is not necessarily best in any other.

 

[ShowerDude]

Dont forget "HL" as a budgetary replacement for the "S" profiles..... All the basic choices anyways

 

[ShowerDude]

Theres a few ways to fill the proper expansion gap, one can pinch foam strips between sheets......... backfill w/ silicone......topical tape.... Packing said gap w thinset defeats the whole point...... Apply common sense

 

[Jadnashua]

From the picture and the angle, there's no way to say what, if anything, was done to the plywood sheet gaps. FWIW, some, not all, cbu manufacturer's address protecting the gaps...they all say the floor install prep needs them during install of the subflooring, but most do not address it when installing their cbu (or, in this case Ditra). And, they offer in some cases a 25-year warranty. Thinset, as opposed to tile, tends to be pulverized in that joint, similar to what happens around the fasteners of the cbu...the ply movement tends to slightly enlarge the hole around the fastener, but the sheet remains intact.

 

[Jadnashua]

Let's take a quick survey of CBU manufacturers, and see what they say about the plywood gaps. First, all of them say that when installing the subflooring, the sheets must be installed with the panel manufacturer's design gaps, then when installing the cbu:

Require keeping the ply gaps clean: Wonderboard

Say nothing about them, and imply filling them (one actually says to do it): HardieBacker, Durock, Permabase

So, since these guys have been in business for long time, and know how their products work, one would guess they have a clue how their products perform. Wonderboard touts itself as the lightest one, and whether that means most susceptible to issue having a joint filled may be why they, knowing their product, and not wanting warranty claims, are the only one of the four that say you must leave the joints free.

So, generalities or a procedure that could work with every product could be used, but isn't needed, if you believe the people that make and warrant at least a good portion of them.

Bottom line, to work, you must follow instructions, and not all products are created equal.

 

[ShowerDude]

John, i learned from tearing our failed floors! Talking to structural engineers, working with better union journeymen in the earl 90s.... Understanding how to assess a joist system for deflection, considering the class rating of tile at hand will all tell you how to build the proper substrate. As for the silicone, i had to backfill my helpers slightly large 3/16. gaps silicone just made sense, i had previously applied that method to my denshield wall applications. Which i no loner suggest. Denshield aka plastic coated drywall!

 

[Jadnashua]

If you want to see a good discussion on the topic and some interesting industry references, check this out http://www.johnbridge.com/vbulletin/showthread.php?t=94786&highlight=Caulking+subfloor+gaps

Not all pros or the industry think like John. There are a few interesting links in the post #39.

 

[Jadnashua]

Obviously, John never read L335...the expansion joints are required to account for moisture during construction (both added like in rain, and in the panels themselves). After the panels have been acclimatized and dried out - the more typical situation of a remodel rather than new construction, here is the section of interest (to me, anyway) that disagrees with what John says and thinks:

Installing Underlayment
Install acclimatized plywood underlayment, smooth side up, immediately before laying the finish floor. For maximum stiffness and strength, place face grain across supports. Offset the end joint of underlayment two inches from joists and offset underlayment end joints at least one joist spacing from subfloor end joints. Edge joints of underlayment panels should offset by at least two inches from edge joints of subfloor panels.

Spacing of 1/32 inch at underlaymanet panel edges and ends is recommended. Edge spacing allows for panel expansion during construction and as the underlayment becomes conditioned to the temperature and humidity which will be typical in service. Edge gaps should be filled just before floor covering is installed (allowing cure time), when no movement is expected.
​

A couple of paragraphs later, it goes into more detail about filling those gaps. If they were so critical, why would they say to fill them with a hard filler? The gaps are there for during construction, when they may get rained on, and before the structure is closed in and conditioned.

 

[Jadnashua]

And, the panel gaps are there specifically for that reason...plus, a good finish installer will have a moisture meter, and refrain from installing his tile and stuff until things have dried out, and certainly won't be installing it until the roof is on and the windows in...maybe even the heating and cooling along with the plumbing and electrical work.

Once things have dried out to where you can actually finish the install, the APA, TCNA, most cbu manufacturers, most sheet membranes (as in uncoupling membranes) say nothing about retaining that panel gap. The APA represents billions of $ in panels installed every year. The TCNA represents probably as much in tiling materials manufacturers...they do not require you to keep that gap during the finished flooring install. They all call for one during initial construction because of that picture you showed...the material may get soaked. But, you cannot install tile on that until the house is closed in and dries out. Or, if you do, you better expect problems. So, John, did you continue to read that APA335 article you linked to, to try to justify your stance? It calls for filling those joints with a hard material, and a good modified, would seem to qualify. But, only after the panels have dried out and acclimated to the structure after being closed in.

 

[ShowerDude]

First off JIM who clarified this conversation relates to NEW construction? and so why start pulling specs and jargon from that scenario? is it to back peddle your in experienced way out of this?


To be sure of your above statement? are you advocating tight or cement filled butt joints at subfloor seams with ( BC exp1 rated ply in a remodel situation ??? )



And refresh our collective minds here .....you have torn out how many subfloors and tented floors in your time? and you have seen the damage seasonal expansion causes all over the US or just in your office controlled climate? You have built up subflooring on all types of Joist systems? Im pretty sure we just showed you the TCNA written specs on subfloor gaps are you saying the TCNA manual is wrong?


Its clear now Jim was indeed in the defense industry. He is always defending his manual experience, and backpedaling his way thru things just like a politician, lobbyist or say A Gov't....... All the while alinging himeself with a Giant propaganda controlled orange Corporation that wants to control the tile world with minions like Jim.

Orange and A retired defenseman. Id say a good fit for each other......lets scare everyone into a fake warranty to sell more of our corporate product. Lets lobby the TCNA and all the others to get them to also push our system. God forbid someone is smart enough to look close at the MSDS sheets and chemical makeup of said products and decide from a educated standpoint if they may or may not play nice with each other in the real world...The world Roberto talks of where things DO NOT work like in harmony unlike Jims myriad of manuals....


Its monday and Jims heading to the jobsite to drop off 20 sheets of ply and tell his client he will be back in 3 weeks when that ply acclimates to the room..........


John prepare you next Cheer for our Beloved subfloor expert...

 

[DougB]

Its clear now Jim was indeed in the defense industry.

Long time ago I worked for Raytheon - Defense. Most of your time is consumed with meetings. Sometimes you get a little something done. Many times they just scrap the project after a year or so - but it keeps everyone 'billable'. Usually there are major cost overruns - so about every two months you get a new project manager - that was the joke: "if you don't like your manager wait a month."

 

[Jadnashua]

John was the one that brought up the picture of the worksite with standing water. John is the one who says he won't install tile until the second layer of ply is installed. John is the one who linked to that APA article. John is the one who either can't read, won't read, or doesn't understand what they say, along with the TCNA, and most of the cbu manufacturers and pretty much all of the uncoupling membrane manufacturers.

And, if your primary market is remodeling...how many houses have standing water in them when you start? The panels have pretty much acclimated to the building as much as they are going to. The main reason they specify plywood for the underlayment is that it is stable, or vastly more so than the dimensional wood.

The biggest issue with gaps in the first layer of subflooring is during initial construction when the panels themselves are wetter than normal and they are open to the weather until the house is closed in...they all call for gaps there. The article addresses both that, and for the precious second layer that is sometimes nice to have, and is sometimes required, especially on a remodel when you may not know the status of the first layer or how it was installed. But, if you do, unless you're dealing with natural stone, the second layer, according to every manufacturer, is optional, in most circumstances.

So, now, not only trying to insult me, people have taken to insulting Raytheon, a $25B company, that builds things like Patriot missile system, many of the sensors that make our satellites work, many of the radars that make the weather forecasting possible, and the air traffic control in many countries around the world...along with lots of other things.