Mapeii does not reccomend on Ditra !

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Mapeii does not reccomend on Ditra !

Discuss Mapeii does not reccomend on Ditra ! in the Canada Tile Advice area at TilersForums.com.

C

Concrete guy

I'm not a huge fan of Ditra matting. My distrust of this product though stems back 20 years when it was completely and entirely misunderstood.

Shops were selling it as some form of super replacements for all sorts of solid substrate suggesting you could use this stuff to tile straight on floorboards, floating floors the lot. I had to correct so many failures.

So rather than become misinformed I spent a long time on the phone (at the time) with Schluter technical. Fortunately now much of this information is available in easy downloads - here's a great info sheet:-

http://www.schluter.com/media/DITRAHandbook-ENG-2013.pdf?v=201306080603

If you look through you will see without exception that the tile is fitted over the Ditra with unmodified thin set mortar. That means no polymer additives at all to comply with the correct installation guides of Schluter.

Things have developed a lot since I stopped fixing but certain constants remains, if I understand this correctly, once you used a polymer modified adhesive on top of Ditra matting the uncoupling mechanism ceases to work or is reduced in efficacy substantially. In so much as it's no longer truly operating as a decoupling membrane.

How does this then dovetail with the BS standards requiring polymer modified adhesives to be used in these situations particularly with UFH?
 
R

Rizzle from the Portizzle

ATSDiamondTools said:
I'm not a huge fan of Ditra matting. My distrust of this product though stems back 20 years when it was completely and entirely misunderstood.

Shops were selling it as some form of super replacements for all sorts of solid substrate suggesting you could use this stuff to tile straight on floorboards, floating floors the lot. I had to correct so many failures.

So rather than become misinformed I spent a long time on the phone (at the time) with Schluter technical. Fortunately now much of this information is available in easy downloads - here's a great info sheet:-

http://www.schluter.com/media/DITRAHandbook-ENG-2013.pdf?v=201306080603

If you look through you will see without exception that the tile is fitted over the Ditra with unmodified thin set mortar. That means no polymer additives at all to comply with the correct installation guides of Schluter.

Things have developed a lot since I stopped fixing but certain constants remains, if I understand this correctly, once you used a polymer modified adhesive on top of Ditra matting the uncoupling mechanism ceases to work or is reduced in efficacy substantially. In so much as it's no longer truly operating as a decoupling membrane.

How does this then dovetail with the BS standards requiring polymer modified adhesives to be used in these situations particularly with UFH?
Click to expand...
would a polymer modified adhesive be your avarage porcelain adhesive
 
M

m3fitter

well.. it does not.. ! so Ardex x7R is totally a different item, I think not.... I only checked this, as the client is a Techi, and has "RESEARCHED" on the internet, and has asked me to clarify and guarantee my products that I am supplying.. as if trying to catch me out.. hahhaa, the ufh is under, anhydrate screed, the tile is 20mm 900x600x20 dense limestone... back in the day, I would have just used flex rapid full stop.. these days, its all about accountability and technicality..based upon info the client is reading..
 
C

Concrete guy

Peter said:
Schluter UK and Schluter USA give quite different advice which is odd. Modified in the UK and unmodified in America if I recall correctly.
Click to expand...

Please bear in mind I'm now talking about conversations that took place nearly two decades ago. Also the last time I used Ditra it looked like a corrugated sheet not lots of little squares stamped into a sheet.

The explanation I was given by Schluter at the time was that the polymer additive in the adhesive improved bonding to a degree that it bonded completely to the matting thereby negating (or at least substantially reducing) it's decoupling performance.

The mechanism by which the decoupler works is the unmodified cement adhesive sets in a perfect match to the form of the matting, think of it like a perfect bed of adhesive shaped exactly to fit the matting itself and it locks in like a key - perfectly. But it doesn't bond completely to the Ditra.

The shear movement is allowed because the bond isn't complete - the mat can move very slightly without pulling the adhesive (and therefore tile) with it.

Once you introduce enhanced adhesion (polymer additives) the adhesive sticks to the mat like poo to a blanket and it's no longer really decoupled.

Has anything changed in the last 15 to 20 years to alter this?
 
C

Concrete guy

Here is Schluters explanation of how Ditra works:-

Uncoupling Membranes - Uncoupling Theory Part 2 - Schlüter-Systems

Here's the UK spec sheet:-

Broken Link Removed

On page 5 of that document it states:-

6.Immediately after the Schlüter®-DITRA 25
matting is installed, the tiles can be set
using the thin-bed method and using a
bonding tile adhesive that matches the
requirements of the covering.

So it doesn't state if polymer modified is or isn't an issue.

It's interesting how there seem to be different specs between UK and USA as Peter mentioned earlier.

It would be very interesting to hear Schluters clarification of this - it used to be big no no (polymer modified) when I fitted Ditra, but things change.
 
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R

Rizzle from the Portizzle

ATSDiamondTools said:
Here is Schluters explanation of how Ditra works:-

Uncoupling Membranes - Uncoupling Theory Part 2 - Schlüter-Systems

Here's the UK spec sheet:-

Broken Link Removed

On page 5 of that document it states:-

6.Immediately after the Schlüter®-DITRA 25
matting is installed, the tiles can be set
using the thin-bed method and using a
bonding tile adhesive that matches the
requirements of the covering.

So it doesn't state if polymer modified is or isn't an issue.

It's interesting how there seem to be different specs between UK and USA as Peter mentioned earlier.

It would be very interesting to hear Schluters clarification of this - it used to be big no no (polymer modified) when I fitted Ditra, but things change.
Click to expand...
its a shame they change at our cost usaly untill the real answers are found by us through trail and error
 
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B

bugs183

As ATS says Ditra has been used to overcome many things it wasn't designed for, but if used correctly it is a fantastic product, we've been using it for over 20 years (started when it was ribbed), and i've never had a failure.
Schluter have always said unmodified in the spec sheet, but how can that effect the uncoupling characteristics of Ditra? I'm no rocket scientist but that makes no sense. When it was introduced we were told that could could fix the Ditra to any substrate with a ready mix adhesive! So things have changed there!!!
So in Mapei's world if you can't use modified on top of Ditra then you can't fix porcelain, or some stone.
Bonkers.
 
Last edited by a moderator:
C

Concrete guy

bugs183 said:
Schluter have always said unmodified in the spec sheet, but how can that effect the uncoupling characteristics of Ditra? I'm no rocket scientist but that makes no sense.
Click to expand...

The explanation provided by Schluter (at the time) was that the extra polymers in modified adhesive "tack" the adhesive to the Ditra and reduce or negate the uncoupling mechanism.

I saw failure after failure with this product back in the day, I saw so many I never used it again. Since this time though the specs and design of the product seem to have changed.

I read a lot on this (and other) forums about people using this product in all sorts of situations in which it appears not to really be necessary. Quite honestly it looks like it's become the emperors new clothes.
 
B

bugs183

ATSDiamondTools said:
The explanation provided by Schluter (at the time) was that the extra polymers in modified adhesive "tack" the adhesive to the Ditra and reduce or negate the uncoupling mechanism.

I saw failure after failure with this product back in the day, I saw so many I never used it again. Since this time though the specs and design of the product seem to have changed.

I read a lot on this (and other) forums about people using this product in all sorts of situations in which it appears not to really be necessary. Quite honestly it looks like it's become the emperors new clothes.
Click to expand...


Go to be honest here ATS i have to disagree with you here. I know that using Ditra has made my jobs more reliable. I've never had a failure whilst tiling onto wood using it, yet virtually every week you see posts where a job that has been tiled to wood directly has failed, ok i never tile to poorly supported wood floors etc, but i've seen enough solid floor fails without uncoupling.
Not sure which jobs you saw all these failures on, so i can't comment on them, but to say that it being a case of emperors new clothes is in my opinion not correct.
Yep it won't replace properly prepared screeds, but it does help i many situations, especially uncoupling underfloor heated screeds.
 
S

Spud

ATSDiamondTools said:
The explanation provided by Schluter (at the time) was that the extra polymers in modified adhesive "tack" the adhesive to the Ditra and reduce or negate the uncoupling mechanism.

I saw failure after failure with this product back in the day, I saw so many I never used it again. Since this time though the specs and design of the product seem to have changed.

I read a lot on this (and other) forums about people using this product in all sorts of situations in which it appears not to really be necessary. Quite honestly it looks like it's become the emperors new clothes.
Click to expand...
Ditra is a totally different product from what it was 20 years ago Alan when it had hessian backing and had channels instead of dovetailed dimples, part of the problem back then was it was mis-sold as a magic carpet solution for floors with unsuitable substrates i saw many failures at that time too but now I am a believer and think it is a good product when used correctly, it is overly specified at times and some builders still believe it to be the magic carpet solution to badly prepared substrates
 
C

Concrete guy

garythetiler said:
Ditra is a totally different product from what it was 20 years ago Alan when it had hessian backing and had channels instead of dovetailed dimples, part of the problem back then was it was mis-sold as a magic carpet solution for floors with unsuitable substrates i saw many failures at that time too but now I am a believer and think it is a good product when used correctly, it is overly specified at times and some builders still believe it to be the magic carpet solution to badly prepared substrates
Click to expand...

That makes a lot of sense it was just an awful product way back then.
 

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