Ditra matting.

[Bri]

Ok..I've got 600sq ft of tile to put down on Ditra matting....(Different job than my mesh/scratchcoat question). Any other time I've used ditra mat, I've followed Schluters instructions, and put the mat and the tile on the same day. Has anybody ever tried putting the mat one day, and then the tile the next? Is there a reason you can't do this? It seems to me it would be easier this way.

thanks

Bri

[Sponsored Links]

[John Bridge]

Hey Bri,

I'll defer to Rob Z. on this one. He's the Ditra guy.

Maybe you'll want to get your two cents worth in on Diane's shower.

http://johnbridge.com/vbulletin/showthread.php?threadid=38


[Edited by Admin on 05-25-2001 at 09:01 PM]

[Rob Z]

Hey John and Bri,

Schluter insists that it's okay to immediately work on the Ditra-walking, kneeling, setting tile. It does seem to me that waiting a day for the bond coat to firm up would be better.

Are you using the new 1/8" Ditra? It's a lot easier to snap lines on it. If you're interested, you can use kerdi at the seams and coves and waterproof the installation.

Have you ever spoken to Peter Nielsen, technical director at Schluter? He's very helpful, and used to be a real tilesetter before working at Schluter.

Rob

[Bri]

Hi Rob
I've called the 800 number a few time and got a recorded message...but..I think you're right..it does seem easier to lay it one day and the tile the next...I'll let you know next week how it works out.

thanks

Bri

[chip]

although ditra matting is a fine product, don't get caught up in that 19" to 24" on center deal.

If you read the fine print, they say that the floor has to meet l/360.

Can you detemine l/360? Do you know what the dead load will be? How about the live load?

These are all factors in determining l/360.

If you have a substrate that meets l/360 and it is a approved substrate for ceramic tile, you can set it with thin set. You don't need ditra mat.

What do you think about that?

[Bri]

Well..the floor is 2x10 wood I-beam with 5/8th plywood subfloor...which is pretty good...but I'm joining to an existing tile floor in which Ditra was already used, so I'm going with it, to keep the same height as the other.
I-360? Isn't that the freeway going through L.A. ?!?

[Bud Cline]

Bri,

You describe your floor structure as 2" X 10" I-Joist with a 5/8" plywood underlayment surface, but actually you have left out one very critical structural factor. What is the spacing of the I-Joist? I would assume they are 16.0" O.C. (on center) but now days one never knows. They could also be 19.2" or 24.0", if the builder was taking shortcuts to save a little dinero.

The 1/360th reference refers to the floors deflection. Here's where I easily become confused, but this is to say that your floor should not deflect vertically more than one three hundred sixtieth of your spans length to be suitable for your flooring application. Anything more than 1/360th deflection would not be suitable for tile, the movement would in time destroy the components.

I've never tiled an Interstate, now that would be a fun job wouldn't it John? Probably a good solid base where deflection wouldn't be an issue.

[chip]

Most people are confused or don't know anything about l/360

the l looks like a 1 bust is actually a L.

l = length

l/360 means length devided by 360 = the allowable deflection

for example: 30 feet = 360 inches, devided by 360 = 1" of deflection allowed in that span.

deflection is up and down movement.

The rule for natural stone is l/720, twice a stringent as tile.

still confused?

[John Bridge]

Flatile,

Welcome to our illustrious group -- well, welcome to the group, anyway. The name is Art, isn't it?

L/360 has always seemed an arbitrary formula to me. Different tiles (and grouts) hold up under different conditions and degrees of deflection. And, of course, much depends on the quality and suitability of the adhesive used. Generally, I don't think the L/360 formula is stringent enough.

You used a 30 foot span for easy arithmetic, but let's take half of that -- 15 feet is more representative of what we might find in a residence. Using L/360, the floor could deflect 1/2 in. over all and still support a tile installation.

L/360 also applies to the subfloor/sheathing/decking between supports. You could have joists that are within tolerance but decking that is not. So the thickness and "stiffness" of the decking is also critical.

Getting back to the 15 foot span, I think L/360 is pushing things to the limit. And even the TCA (who came up with the formula) states that this is a "minimum" standard. A more prudent standard would be the one recommended for stone floors -- L/720 applied to the over all span and to the decking between framing members as well.

There is another thing that is seldom touched upon, and that is the "nature" of the live load on the floor. A floor where a number of people are constantly walking (maybe even jumping) will necessarily need additional shoring up, no? Can you imagine, for example, a group of kids (in a day center, maybe) doing a daily regimen of jumping up and down in unison in the middle of the floor? How long before the grout comes popping out?

Anyway, you say that if a floor meets the L/360 standard, it can be tiled without any additional consideration. And then you say, "What do you think of that?"

Well, I think we all need to think a little bit further.

How are things in Sunny Florida these days? I hear Janet Reno is going to be your next governor.

And I wouldn't want to tile the freeways around here. We have plenty of deflection. We are afloat on a sea of mud here. I've got my house chained to a tree to keep it from floating off toward the Gulf of Mexico.

[Edited by Admin on 05-26-2001 at 07:22 PM]

[Bud Cline]

I don't know that I have ever seen a 30ft span that deflected 1 inch, or a 15ft span that deflected 1/2 inch. This is why I have always had a problem with that formula. Surely building codes must be more stringent than that.

I know boxing and wrestling rings have a great deflection, they are designed that way to break falls. A trampoline is the only thing I can think.....oh well never mind.

And isn't L/360 another way of saying 1/360th?

[Harry]

1/2" over a 15' span to me would well exceed anything I would (knowingly) allow. That seems like a lot, if I see any flex whatsoever I get a little nervous.

[kalford]

Does deflection make me uneasy!? Let me tell you what I did in my 30sq.ft. bathroom.

The old linoleum was torn to pieces and the wood was rotten including the subfloor.I tore it ALL out down to the floor-joists.They were on 16" center, 2"x8", running the length of the bath(door to back wall.I added five pillars of concrete blocks.One on each side of the toilet,one at the doorway and two between the door and the tub.I then added 2"x8" braces crossways between the floor joists also on 16" centers, so the joists looked like a 16"x16" grid.
I put 5/8" plywood on top and srewed it in place with 2" decking screws.I put another layer of 5/8" plywood(in opposite direction)on top of that and screwed it down also.Then I put down 1/4" Durock and screwed it with 1 1/4" backerboard screws every six inches.I set the 12"x12" tile in C-cure Multi-Flex Strata latex modified thinset and grouted.
Over-kill? Absolutely!! And I sleep like a baby!

[chip]

Yes the l/360 is the minimum and the live load is a very subjective issue.
How about the last minute decision to add granite counter tops and that impulsive decision to buy a piano.(dead load)
Then you decide to show it all off with a big party, with say 25 to 100 hundred of your closest friends.(live load)
If your architect or engineer didn't plan for this impulsiveness of yours, look out.
The average tile contractor, let alone do-it yourselfer, isn't qualified to make these derterminations. And certainly not any manufacturers Rep's that I know.
So when a manufacturer such as TEC and Schluter, make claims of there products working over 19" and 24" on center installations. It drives me crazy, that they think they have re-invented the way you can install ceramic tile. Even as they hide behind the cloak of the l/360.
I will say it once again if you can assure your self that you are installing tile on a substrate that meets the l/360
requirements, you can use thin set or medium bed mortar depending on the size of tile.
These company's offer fine products, it's there marketing people who need to go back to the drawing board and learn some ethics.

[John Bridge]

Keith,

Sounds like a bullet-proof bath floor all right. Gonna hold a party in there?

Art,

I think you're a man after my heart after all. Why don't you tell us who you work for? Go ahead and list the site if you want to.

[Rob Z]

Art

I agree with many of the things that you have pointed out so far on the Forum. I agree that there are MANY people in the tile business (installers, reps, sales, tech support, etc) that don't have a clue what's going on. And, this situation is not confined to the tile trade. I encounter the same things in other aspects of my remodeling work-plumbing, paint, carpentry, and so forth. That's why I stick with a small group of suppliers and products. Over the years, I have weeded out a lot of the people and products that don't help the job go foward successfully.

In the tile business, the few product reps that I rely heavily upon were all tile setters or other tradesman before working at their respective companies. It doesn't take long to determine whether they know what they are talking about from an installation standpoint. I think it's good to know that they are there after a successful carreer in the trade, not because they couldn't cut it as an installer.

On the issue of using Ditra: About a year ago, I read a technical paper about Ditra that was written by an engineering professor and the technical director at Schluter. It had been many years since my academic days, so some of it was over my head. For all I know, all the data and results are fabricated. But I do know that Schluter Ditra offers a better warranty most other manufacturers of tile products. Ditra installations are covered by a five year full warranty-labor and materials, plus tear out of the failed installation. I have to assume that Schluter has tested the heck out of this product to be confident enough to offer such a warranty.

I think it's over simplifying things to conclude that a substrate that meets L/360 is then ready for tile set with thinset. Ditra offers benefits other than just being a direct substitue for cement board. I think the greater speed and ease of installation as compared to cement board is reason enough to use it. Reducing the weight of underlayment (Ditra vs cement board) is going to help with deflection issues.

Ditra offers crack isolation, waterproofing, vapor pressure equaliztion, movement absorbing properties, and reduces shear stresses on the tile. For example, next week I start a job over a basement slab where the vapor pressure issue issomething to consider. Ditra gives me a solution. Cement board itself doesn't help with any of these issues.

I personally almost always over engineer an installation. If the specs say a single layer of plywood is okay under Ditra or cement board, I add a second layer of T&G for increased stiffness. I also use a ultra premium thinset, not the cheap stuff.

But, if an installer wants to follow specified instructions for a product that is covered by a warranty, I don't think that is being reckless. With so many unscrupulous, unqualified, cheap installers out there to compete with, I consider myself fortunate that prospective customers will pay for the premium products that offer additional benefits over what the other guy claims "Oh, you don't need to worry about that (problem), I've been doing it this way for years with no problems...Usually, these are the same guys that follow up with a request for 75% deposit two months in advance, in cash.

Other than tile-over-drywall installations, there isn't any one installation method that I can unilaterally condemn. After 11 years of tile setting, I have seen so many installations that worked, even though they didn't meet industry accepted guidelines, that I think the much discussion is possible without any hard and fast answers or conclusions.

The fact is that much of our collective experience and conventional wisdom of "how to do it correctly" is anectodal. Sure, the TCA can conduct tests in its lab and set standards such as L/360. We can debate like crazy on the Forum and elswhere about what is "right".

BTW-I don't have any vested interest in Schluter or any other product. I do, however, have a big stack of cement board out in my garage that is marketed by your company.

Time to go clean out the van for another week of work!

Rob Z

Bri-try the 800 number again. I've never had a problem getting through.

John-I still think mud is the best. I've done quite a bit of mud this month, and have perfected my "standing around" technique, as well.

[John Bridge]

Okay, when you get the "standing around" down pat, don't forget to work on "sitting around." It's equally important.

[chip]

WOW!!

Please note that I initiated my comments on Ditra, by saying that it is a fine product and my only concerns were that their guarantee over 24" on center floor joists, is bogus.

It is commendable that you show loyalty to particular manufacturers and suppliers whose products have a track history.

Unfortunately I can't make claims of a back ground in the installation business. I've had many jobs prior to my involvement with the floor covering industry most directly with ceramic tile.

What I've done is listen and ask questions, until I'm satisfied that I have a understanding of the situation and can talk intelligently about it.

After 7+ years of doing such, my wife and I have transferred with the company I represented independantly in Michigan, Ohio, Pennsylvania & Western New York. I have taken a full time position with them in South Florida.

I thought I had a pretty good grasp on how tile was set. Boy was I shocked with all the wicking paper and floor thin set being used.

I'm all ears, which is why I have joined this forum and will not always make the proper statements and or suggestions but I will look forward to being corrected by the masters of the trade who also subscribe.

John,

Thank you for your kind comments and the name of the company I represent is one that no doubt will be unfamilliar to you, since we don't distribute into Texas.

The company is the W.R. Bonsal Co.
Their web site is http://www.bonsal.com

We look forward to all of you exploring our web site and take a look at the Pro-Form section in particular. These products are new to the industry.

I promised no advertising and to keep my comments generic and I appologize for the previous comments, but you asked.

[Bri]

Hi Everyone
Great debate here!...now..what was my original question? Oh yeah..putting down Ditra the day before..I think we all agree that a start from scratch mud job is the best way to go...unfortunatley..You can't always do that, and you have to go to the next best alternative. It would be nice to turn down work and stick to your guns about installation methods, but I've got bills to pay. As far as shoddy work goes, I guarantee my work forever, so I have to make sure it lasts. But I also think that new products have to be tried and tested..before we condemn them. I've used ditra quite a few times, but mostly in small areas. It seems to do what they say...no problems yet. In a larger area,I wasn't sure...that's why I asked the original question. I appreciate all the feed back though!

thanks everyone

Bri

[Bud Cline]

My DITRA experience is limited at this point because most of my work comes from retailers and they are reluctant to try new products. Makes no sense to me. I have always installed DITRA one day then returned the next to do the tile. It is said the DITRA can be installed and you can then get right back on it to begin the tile but frankly that worries me a little. I just felt as if movement on freshly installed DITRA would cause unnecessary displacement of the thinset and I don't know what else. I'm just not comfortable doing it.

I have refused to do jobs that in my opinion weren't viewed properly and thoroughly by some hotshot inexperienced salesperson doing touch-n-goes at a prospective jobsite. I won't lie to you, it has cost me dearly from time to time. The thing is they expect me to guarantee my work so it is MY WORK that I guarantee, not someone elses. For me to guarantee my work I must do the engineering on the abnormal jobs. It's either that, or I want the specs in writing from an architect, and oh ya that's gonna happen every day.

Hey flatile, we use composeal all the time here. I have also used a product called Pro-Form but it wasn't what I saw at your website. This product was a styrofoam product used for sloping shower floors. Wierd!

[kalford]

Bonsal? I,ve used their wall grout. Fantastic product!I'm not familiar with much else they make though.I'll be sure to check out that site.

Bri,
I personally have a concern about breaking the "key" by walking/crawling on a freshly installed underlayment especially when the ONLY fastener is the thinset.One can only reap good rewards by being a little patient and allowing an appropriate curing time before subjecting the adhesive to the stresses of someone crawling around on it.

Thinset has what I call a "vulnerable" time during the curing. When you first spread the thinset it is very strong(sticky)but after a short period of time,when it has started to stiffen but is still wet, the "key" can be broken very easily.This makes me a little uneasy about sameday installation of the tile. This "vulnerable" time varies according to how the thinset is mixed,ie;thin or thick.

This vulnerable time does NOT discriminate between Latex modified or standard dry-set.

It's not as big a concern with CBU's that are srewed in place but if the floor has noticeable deflection when you walk on it prior to installing the CBU, I let it set!!

[Bri]

I totally agree....but no where on Schluters web site does it say anything about waiting a day before installing the tile....it made me think that maybe the weight of the tile held the mat down. I'll be calling schluter in the morning...during business hours that is.

thanks

Bri

[Bud Cline]

Bri,

Here's what your looking for maybe. I found this at schluters website: http:/www.schluter.com/english/products/h6.1-ditra.htm

Immediately after the DITRA matting is installed, the tiles can be set using the thin-bed method. Using a notched trowel that is matched to the type and format of the tile, apply the bonding mortar in a single process. Solidly embed the tiles in the setting material, making sure to achieve full coverage. Please observe the open time of the adhesive. Estimated thin-set coverage to bond tile to the DITRA using a 1/4” x 3/8” (6 mm x 10 mm) square- or U-notched trowel is 60 - 65 ft2 per 50-lb (22.7 kg) bag of mortar.

Still don't like the idea of working on freshly installed DITRA.

[chip]

I'm with you on the curing time of the thin set under ditra,
although their thinking may be the same as the T C A and a Product manufactured by Fin-Pan, called Util-A-Crete.

They were experiencing hairline fractures in tile installations and found that using a poly mod. or latex mod.
thin set and adhereing to the floor, they could anticipate fractures due to the movement of the plywood underlayment.

To my knowledge, Util-A-Crete is the only cement backer board that agrees with the T C A and requires dry set mortar as a leveling bed.

By using this product and method you have a life time warranty.

On second thought Schluter is recommending multi-purpose thin set under their ditra, so they want it to stick to plywood, and you being on it before it cures can cause bond failure.

[chip]

I forgot in my previous message to tell you we appreciate your business with composeal products, and that the pro form product you used was probably a product called pro slope.
Pro slope is now marketed by The Noble Co., and has white styrofoam pellets between sheets of cardboard.
This product was invented and initially marketed by a great guy from Utah, named Lonnie DeGoyer, and Lonnie if I spelled your name wrong, I appologize.

Pro-form, has no cardboard and is expanded poly styreen.

Kieth,

Thanks for the plug on the grouts. We have tremendous success with them and as you know the least expensive part of the job (grout) has a huge impact on the overall job.

[John Bridge]

I am extremely impressed with the quality of the dialog here, and for once I think I'll just keep my mouth shut (Dave G. wouldn't believe it). I will float the Bonsal url across the Internet once more, though.

http://www.bonsal.com

[Bud Cline]

Flatile,

You are correct it was Pro-Slope, I stand corrected. I don't remember the cardboard sandwich though. I used the product one time and though I am aware of no problems I just never bought any more. I did show it to local retailers but to my knowledge they chose not to even try it. Your pro-form I've not used. That type of thing usually isn't my call anyway.

[chip]

Most of you are running into shower pan liners that lay flat on the floor when you arive on the job.

If you are aware that your PVC liner should be sandwiched between to sloped mud beds, you don't or won't remove the liner installed by the plumbers.

So the mud bed is installed over the PVC liner that lays on the floor. It is "normally" sloped pretty well.

The problem with this scenario is that when the water from the showers goes through the grout joints, it doesn't have an avenue, such as the presloped PVC shower pan liner, to get to the weep holes built into the drain. And there may or may not be pea stone or chips of tile piled around the weep holes to allow the water that some how makes it's way to the weep holes to get through and down the drain.

So this moisture who's only way to get out of the mud bed is evaporation back out the grout joints. But it gets re-wetted every shower.

If the shower bed was built up to the walls the walls will wick moisture 1ft. to 2ft. up the walls and the grout will not stay the same color as the rest.

For those who know about this procedure and the problems that exist, some still don't want to take the time to allow the 1st sloped bed to cure and come back the next day to put the liner in place and then build the 2nd sloped bed and allow it to cure till tommorrow, before you can tile.

That is why Lonnie invented Pro Slope and Pro-Form offers our slope. It brings it back to a job you can do today and tile tommorrow.

Boy am I getting long winded, sorry!!!

[Rob Z]

Flattile

Has the warranty for Utilicrete changed recently? My most recent Fin Pan literature lists as a warranty only the replacement cost of the cement board if it is defective, assuming it has been properly installed, etc.
The literature I have is from last Fall.

Rob Z

[chip]

The warranty hasn't changed.

Realistically warranties are worth about as much as the paper they are written on.

What we are saying is that concrete adheres to concrete, and has through the ages.

If you need water proofing, then maybe ditra is for you and your job requirements.

But if you don't, why are you using a water proof material to make your own board with multi-purpose thin set, top and bottom?

Fin-Pan originally made Wonder Board, The 2 companies split, and Util-A-Crete was born, due to the fact that Fin-Pan had the manufacturing equipment.

Util-A-Crete is what WonderBoard was originally, hard with a tight mesh. Is it heavy? yes. You want light concrete?

I'm off my soap box and off to work. Have a good one.

[Rob Z]

Flatile

Don't get me wrong-I love Utilicrete and use it exclusively when I use cement board. I have pallet of 1/2 x 3 x 5 and a pallet of 1/2 x 3x 4 Utilicrete in the garage right now. I was trying to follow up on your comment about the life time warranty of Utilicrete. Let me clarify my original question: does utilicrete have an installation warranty or not?

I don't view using Ditra as making my own cement board. If one believes and understands the engineering principles behind Ditra's design, it's offering a lot more than cement board ever can.

And even if Ditra was merely comparable to cement board, I would still prefer to use it on floors that didn't need mud. After installing 1000's of sheets of CBU on floors over the years, I'm ready to make the switch.


Well, I am off to work as well.

Rob Z

[chip]

Thank you so much for the business. I'm proud to be part of the select group that you are loyal to.

Util-A-Crete's warranty is as stated. Replacement of the product.

I agree once again that ditra is a good product.

Other than the weight differential& water proofing what is the benefit?

[kalford]

It offers a height advantage being only 1/8" to 3/16" thick.It is easy to install and saves time because there is no need for nails or screws.It offers better adhesion because of the waffle design.It acts as an uncoupling underlayment thus isolating the tile from direct stresses due to subfloor movement, which is the main objective in any installation......and it's a pretty ORANGE!!..........I'm a Tennessee fan.....imagine that!

[Bud Cline]

Keith,

I only have one thing to say to that: "GO BIG RED".
(Husker you know) :D

[chip]

hieght advantage is good, no fasteners is good, uncoupling is better.

1/4" cement backer board is close.
cement backer board set with dry set mortar is always uncoupled (as is a mud job with a slip sheet)
cement backer board costs less.
cement is heavy. You can't be everything.

[chip]

Were working on Orange and Red, but I would prefer Maroon & Gold, the colors of the chippewa's of Central Michigan Univ.

[kalford]

Yeah, I forgot about you being a Husker Bud! My second favorites are the Seminoles then the Huskers. I can't stand the gators!!

Flatile, be careful mixing them colors.You put Orange and Red together and disaster is sure to follow!LOL

Keith Alford
"Install it Right,Bet on the VOLS,Win Lots of Money"

[John Bridge]

Speaking of colors, I don't know whether you've noticed, but we've launched a brand new decorating forum. Two lovely ladies whom I work with a lot have agreed to moderate the thing.

It takes a while to get people interested in a new board, and there has been no action there as yet. It would be very nice if certain people jumped on over there and said hi to Marla and Susan. (hint, hint)

http://johnbridge.com/vbulletin/showthread.php?threadid=47

[Bri]

Hello Everyone
600 sq ft of Ditra Matting went down today....this stuff is a vacation compared to Concrete board!...never even broke a sweat today. I hope Ditra performs as well or better than the CBU's, because if it does, I'll be switching. Even though it's more expensive, it saves a lot of time and sore muscles..so it's worth it. Plus I didn't have to hear a hammer or screw gun all day...and no dust!...cut everything with an olfa knife. I've done a few bathrooms and entrances with ditra before, but they were all quite small...doing a larger area really showed me how easy it was to install. Tile tommorrow...wish me luck.

Brian

[John Bridge]

Good luck, buddy. Did you ever tell us how you got the old mess out of the way -- the giant chicken feet, etc.?

[Bri]

"Did you ever tell us how you got the old mess out of the way"...John...what's my wife got to do with anything?...It's just a joke!...Hell..I'm not even married(Go figure)...anyway...this is a completley different job...new home...so no mess to take out on this one...the "chicken Feet" job is still to come...I might get Harry to help me on that since it's just down the road from him.(By help I mean cold beer in his Fridge)..and I'll need it after ripping out all that tile and wire lathe.


Thanks

Brian

[Rob Z]

Hey Bri

What's an "olfa" knife?

Rob

[Bri]

It's the BMW of utility knives..

http://www.olfa.com

Brian

[Rob Z]

Hi Bri

Thanks for the tip.

Rob

[Bri]

Put all of the tile down over the Ditra today...everything went according to plan... a few things I noticed...I put a skim coat over the Ditra yesterday, to fill in all the depressions in the matting...I thought it would be easier to see my chalke lines today. I did leave 2 smaller rooms as is...Well, as it turns out, it was easier to see the lines, but more difficult to level up the tile. The rooms without the skim coat, let me push the tile down into the thinset, while the skimmed section was a bit of a battle to level up. Next time I'll leave it without. Grout day tommorrow...hope it's dry enough..no place for the moisture to go, with all that pvc under the tile.

Brian

[John Bridge]

Bri,

Please tell me you had help putting down 600 feet of tile in one day -- taking time to level up individual pieces. Do you not sleep, my friend?

[Bri]

Yeah..me and another guy...no helpers though...we can put down a lot of tile in a day if we put our minds to it...but we're getting old now, so we spend a lot of time saying things like " Remember 20 years a go" or " If we were 20 years younger we'd be done by now" or" Do your knees hurt or is it just me"...you've probably heard or said them all. My favourite these days is " Did you get your ticket for the lotto tonight"?

Brian

[John Bridge]

Whew!

[Rob Z]

John

How come Bri is a "member" but I'm only a "junior member"?

Bri

The Schluter rep told me that the skim coat in the waffles was a no-no. It affects the performance of the design (he told me).

I thought I had seen it all, but today I took over a job where the previous contractor filled the trench for the groundworks in the basement slab with thinset and gravel(!)

Rob

[Bri]

Rob
I think it's based on number of posts...

Interesting about the skim coat...though I'm not too worried..filling the waffles the day before, or on the same day as the tile, is still filling the waffles, so I don't see what the big deal is...the thin set still sticks. Unless I'm missing something like shrinkage. Besides if it's a no-no they should say so on the instructions.

Brian

[John Bridge]

I had this thing professionally installed on the site, and the options were pre-set. I can change them, but I'm going slow. Some of you will remember how I used to screw up the old forum and then have to beg Dave B. to fix it.

As far as membership, one of the other sites that uses this program has people labeled as apprentices. I've got a feeling all you old pros would rather be called junior members for a while.

[Bri]

Well..just as I suspected...the tile over the Ditra wasn't cured enough to walk on....stupid weather...went down to 7 degrees C last night...and there is no heat in the house yet....so guess who's grouting on Saturday?..it's ok..I'll pay myself overtime.

[John Bridge]

A couple comments.

If it stays that cold more than one night, you'll be well into the summer finishing that job.

And, I know how to pay myself overtime, too. I go out and get another six-pack. Benefits ain't great in the world of the self-employed, but God, it's like show biz, isn't it Bri? You just can't leave it alone. Besides that, no responsible employer would have you.

[Rob Z]

Bri

I emailed Peter Nielsen, technical director at Schluter, to ask him about the skim coating question. He said it should be avoided if possible because it introduces a cold joint between the skim coat thinset and the setting bed thinset.

You need to convert to Fahrenheit for us SAE guys. What's 7 degrees C?

Rob Z

[kalford]

Too cold to lay tttttttttile.

[chip]

So if you create a cold joint with ditra, what about setting tile to a slab?

[John Bridge]

7C is about 42F. And around here if it gets down around 60F we think about taking the day off.

[Bud Cline]

Good question flatile. What about "patches" on slabs that receive tile?

Once the (first pass) thinset is locked into the mat (DITRA), how is the application of thinset for tile any different than the application of tile on concrete?

[Bri]

At least the beer stays..well cool. I understand the concern over a cold joint using concrete or mortar..contrary to popular belief, cement doesn't stick to itself very well. But thin set IMO will stick to itself as well as to the matting, thanks to the polymer bonding agents.

[chip]

Where did the Romans get their polymer agents back then?

[chip]

By the way, don't you ever sleep man, it's 3:36 by your post man.

Or did you close some micro brew and stop for some tofu on the way home, mavbe some bean sprouts?

Just pulling your chain, I like some of the stuff too.

[Bri]

Even the Romans used a slurry to stick cement together back then...I would think...3:36? is that what time it was? I fell asleep on the sofa and woke up at 3am and could'nt get back to sleep...which was good I guess since I got to the Ditra job by 6am and was finished grouting by 10. By the way, the floor was solid as a rock...I was pretty impressed considering how thin the Ditra is.

[chip]

The slurry thing is on the right track, but the term scares me.

Slurry, being a heavily wetted material, it can cause a weakening of your cement.

But once again you are headed in the right direction.

[Rob Z]

Bud, Art, and Bri

Too much beer drinkinbg in college has made my memory recall WAY too sslow.

As I set some tile over Ditra this past few days, I remembered what the Schluter rep explained a year or so ago. Thinset on the topside of Ditra is not designed to be a bonding agent. The thinset fills the cavities, waffles, dovetails on the older style of Ditra, cures and is bonded to the tile above. The thinset is mechanically or geometrically locked into the face of the Ditra sheet.

Larry (our local rep) showed us a piece of the old style Ditra where you could slide the tile and thinset out in a direction parallel to the grooves. The dovetailed thinset was stuck to the back of the tile in perfect rows. It looked like Norm Abram's dovetail jig made the shapes. The point was that the thinset isn't intended to, nor can it, stick to plastic.

You're right, it should be listed on the package/instructions if we shouldn't do the skim coat thing. It's for people smarter than me to decide if a solid column of thinset in the waffle is stronger than two short columns that are bonded to gether to form the same height.

Hey Bri, do you get a sore palm from leaning on the ditra? I trowel with my right hand and put my left hand down on the mat. Maybe I need to start wearing one glove.

John, can you get an engineer type to join the Forum to answer these pressing scientific questions?

Rob

[Bud Cline]

Rob,

What you have explained is easy to see. Sliding the piece of tile and all that. I'll buy that, and wouldn't expect the thinset to mechanically adhere itself to the plastic DITRA.

BUT, I still think an application of thinset onto a previous application of thinset will in fact bond. I would be glad to have someone convince old stubborn me that it would not be the thing to do. Why? I'm from Missouri, SHOW ME!

>>>>>>When I get into a big job on concrete or CBU, I begin to develope the same discomfort with my left hand supporting some of my weight while spreading thinset. For many years I have done just what you suggest and wear one glove. I have the fingers cut out though. It works fine.

[Bri]

Hey Rob and Bud and everyone

Curious that you mention the sore hand from leaning on the waffles..yeah..by the end of the day it was killing me...and I was also wondering about the adhesion to the plastic and questioned (to myself) why Schluter doesn;t make the surface a little rougher(it's very smooth)since anything would help. I will do the installation the way Schluter advices(next time)..but I must admit it stuck pretty good with the skim coat...thanks by the way, for checking in with schluter for me..I never did get an answer from the Canadian 800 number.

Brian

[Bri]

I should mention that when I skimmed the ditra, I used a grout float,which filled the the waffles, but left the orange cross sections clean.

[John Bridge]

Rob,

I don't know if a self-respecting engineer would want to get mixed up with this group, but we can put out a plea.

Please! Please, Mr/Ms Engnineer! Show us the light!


What about Dave A.? Is he a real engineer?

[chip]

Now I can see the Schluter rep's concern.

With the organge screeded clean, the only bond you could achieve with your thin set would be to the thin set in the waffles, and not on the orange mat itself.

So yes you did leave a lot of cold joints.

Hopefully it will hold up, if not just blame the thin set manufacturer, everyone else does. (A new can of worms opens)

What part of Canada are you in anyway? I looked at your profile, and prviously just assumed Ontario.

Art

[Bri]

Hi Art

I sorta see your point...I think?..since the thin set doesn't stick to the plastic..then...ummm..Oh Hell...I don't know...as far as I'm concerned, the only way the tile can come loose is if the thin set comes loose from the waffles..but the thin set is stuck to the waffles...and the waffles are plastic?...but the thin set doesn't stick to the plastic?..and....AAHHHHHHHHHHHHHHHHHHHHHHHHH!

Yes Ontario...right accross the lake from Rochester NY.

Brian

[Bud Cline]

Yeah !!! Now I am going to back away from my insistance that the second coat of thinset will bond to the first. I hadn't considered the fact that the plastic (DITRA) was exposed.

My minds eye that was seeing a 100% thinset contact surface is now seeing only about a 40% contact surface. Now it's sorta scarry in my judgement. Now I see what could be considered a cohesive failure of the thinset.

[Bri]

Bud
But the plastic is always exposed? First coat? Second coat?What's the difference? The thin set doesn't stick to the plastic...but the thin set will stick to the thin set? Right? I should mention that the waffles are dove tailed so the thinset can't pull out of the depressions. and I would think the waffle coverage is more like 70%.

Brian

[Dave Ashton]

Hi John...very nice update to your forum. My ears were burning so I thought I'd drop by. Yes, its true, I am an engineer. But Im a tile setter as well. My engineering experience is basically structural stuff. But I do alot of inspection work as well. So, Im happy to answer questions as I have time to check the forum.

If you are wondering why the general post under the DITRA line, ask Rob...oh, is that why my ears were burning?!

Dave

[Bud Cline]

Bri,

I think in a first and only application of thinset onto and into the DITRA profile the thinset from the dovetail cavity to the base of the tile would be continous so to speak. Thereby less opportunity for a cohesive failure.

I can also see where an application of thinset onto and into the DITRA profile that was then skimmed but this time allowing a layer of thinset to remain atop the DITRA surface would also work. This is how I had first interpreted your statement. Thereby any subsequent application of thinset (to set tile later) would have the ability to "lock" 100% thinset to thinset. This method is what I had first visioned that would be no different than a thinset to concrete marriage.

I gotta stop now I'm getting confuseder and confuseder.

[Bri]

Me too!..but thanks!

Brian

[John Bridge]

Dave,

Welcome back. Yeah, we need an engineer, and I hope you'll stop by from time to time.

I guess you've been busy.

[Bri]

I seemed to be obsessed with underlay these days...I got a flyer from Mapie today about a new product called PRO-FLOAT. Anybody seen this stuff? It's a 16x16 inch grid that interlocks with a honeycomb pattern that you fasten to the floor, and then fill the honeycomb with some sort of screed material. Comes in 1/4 and 7/16 and is suitable over 5/8 subfloor 2x10 16" oc and has a lifetime warranty. It also bends to go up walls and can be used on shower floors. My cost was about $1.20 sq ft, not includeing the screed material. Jeeezz..I was just getting used to Ditra.

[John Bridge]

Haven't seen it, but "pro float" sounds familiar. There was a product (precursor to a bunch of others, I think) about 15 years ago. Sort of a honeycomb thing that went on the wall. Then you floated mortar on/in it. It was supposed to replace lath and mortar in showers and tub backs.

I was bumming abound a tile supply the other day, looking at the rack of Schluter nosings, and there lay a stack of video tapes on "Ditra." Picked one up. Haven't looked at it yet, but maybe "y'all" would want to round one up. I'm saving mine for Sunday afternoon.

[Bud Cline]

In this same vane. Do you guys remember a product that came out just a few years ago I think from Laticrete?

This stuff was plastic panels that would interlock into a grid system, it had holes to nail thru for attaching to a wood subfloor. It also had thousands of little plastic fingers sticking up (Astro Turf style) and you would fill (skim) these fingers (grids) with "mud" to create a uniform "mud base" for tile.

Whatever happened to that stuff I wonder???? Used it once with fair success as I remember and then it disappeared.

[John Bridge]

Hey Bud,

That sounds almost like the same stuff Brian just described. Maybe it's the same outfit.

[Bud Cline]

Yeh that's what made me think of it. Hey Bri is this Pro-Float product hairy? I could swear this other was from Laticrete but maybe not. I'm trying to time-line the stuff, must have been five or six years ago.

[Bri]

Bud
It sounds similar..but I think this is new. Mapie have a section about it on their web site..but no pictures..so I have no idea what it looks like. Even the flyer they sent me doesn't have a picture.Hmmmm?...what could they be hiding?

[Bud Cline]

Probably nothing to hide, Probably just a "rush to market". Just "smacks" of laminate flooring doesn't it?

[Rob Z]

Bud

I think you may be describing Laticrete's Quick Screed. There were failures ahoy here in the VA area a couple years ago. They reformulated it, and apparently it's okay to use now.

I haven't been brave enough to try it again.

Rob Z

[Bud Cline]

"That's it". I recognized the name the instant I saw it. Haven't seen it for a long time though.