[kirm]

I posted this in the contractors forum but I didn't belong there, sorry.

Anyway, copied from there:

I'm doing my kitchen with Ditra XL and have run into a little problem. It's actually pretty damned big as it means I've wasted a lot of time and have to do everything over again, most likely. The Ditra doesn't seem to be sticking to the modified thinset.

Subfloor: 1x8 diagonals, original from 1955. Screwed down to the joists 16" OC.
On top of that: 5/8 T&G exterior grade plywood screwed down to the diagonals. 4 inches on edge, 8 in the field
Thinset: Mapei Ultraflex 2 - the bag was about a year and a half old
Trowel: As recommended by Schluter without buying their overpriced one.
Method: floor dampened with a sponge. Thinset was fairly fluid but still held a ridge. XL applied, then pulled up. Sure enough it had only about 60 percent coverage so I had to put down more thinset and try again. That got pretty tiring. I seem to have to do that everytime I use Ditra.

And my reward for all that work and money? While vacuuming I notices some of the XL pulled up. I began to cut up the parts that weren't stuck.

I've talked to my supplier here and he's trying to get in touch with the Mapei rep. I'm really disappointed and a bit angry about this but what can I do? So...what can I do?

What do you guys think was the failure and, more importantly, how do I fix it?

In addition:

BTW, I've started to pull up the rest of the Ditra. Comes up easy as pie with a slight zipping sound. That thinset didn't stick to the XL fleece. I believe I could use this Ditra over again if I had to.

I'm using a putty knife to bring up this thinset now. Some peels up easy and some doesn't. Either way it wouldn't matter the fleece is simply not firmly embedded in the thinset. Still waiting to hear from Mr Mapei but who am I fooling...it will be all my fault...even if it isn't, if you get my meaning.

Right now I'd love an idea of how to get this junk off my floor. At the rate I'm going it will take days. I think I'm going to be switching to Laticrete...I have no idea why I feel that way.

 

[ktl5005]

I posted this in the contractors forum but I didn't belong there, sorry.

Anyway, copied from there:

I'm doing my kitchen with Ditra XL and have run into a little problem. It's actually pretty damned big as it means I've wasted a lot of time and have to do everything over again, most likely. The Ditra doesn't seem to be sticking to the modified thinset.

Subfloor: 1x8 diagonals, original from 1955. Screwed down to the joists 16" OC.
On top of that: 5/8 T&G exterior grade plywood screwed down to the diagonals. 4 inches on edge, 8 in the field
Thinset: Mapei Ultraflex 2 - the bag was about a year and a half old
Trowel: As recommended by Schluter without buying their overpriced one.
Method: floor dampened with a sponge. Thinset was fairly fluid but still held a ridge. XL applied, then pulled up. Sure enough it had only about 60 percent coverage so I had to put down more thinset and try again. That got pretty tiring. I seem to have to do that everytime I use Ditra.

And my reward for all that work and money? While vacuuming I notices some of the XL pulled up. I began to cut up the parts that weren't stuck.

I've talked to my supplier here and he's trying to get in touch with the Mapei rep. I'm really disappointed and a bit angry about this but what can I do? So...what can I do?

What do you guys think was the failure and, more importantly, how do I fix it?

In addition:

BTW, I've started to pull up the rest of the Ditra. Comes up easy as pie with a slight zipping sound. That thinset didn't stick to the XL fleece. I believe I could use this Ditra over again if I had to.

I'm using a putty knife to bring up this thinset now. Some peels up easy and some doesn't. Either way it wouldn't matter the fleece is simply not firmly embedded in the thinset. Still waiting to hear from Mr Mapei but who am I fooling...it will be all my fault...even if it isn't, if you get my meaning.

Right now I'd love an idea of how to get this junk off my floor. At the rate I'm going it will take days. I think I'm going to be switching to Laticrete...I have no idea why I feel that way.

That is b/c when yo read the directions of the Ditra, it requires an UN-MODIFIED thinset, NOT modified

 

[kirm]

Not according to Schluter. Modified over plywood, OSB. That was told to me in a support call directly to Schluter. In addition, the place I bought the Ditra/thinset, a pro tiler shop, told me to use modified over plywood. And finally, here's a quote from the FAQ on Schluter's site:

"The type of thin-set mortar used to install DITRA depends on the substrate material. For example, to set DITRA over plywood or OSB, a modified thin-set mortar meeting the requirements of ANSI A118.11 is used. To set DITRA over concrete or gypsum, Schluter-Systems recommends an unmodified thin-set mortar meeting the requirements of ANSI A118.1. Please consult the Schluter-DITRA Installation Handbook before beginning your tile project to confirm the proper materials selection."

 

[ktl5005]

My bad I read you wrong. You are right. Modified under DITRA, unmodified on top of DITRA to set tile.

What size trowel are you using?
What kind of time frame did you give it to cure?

 

[oh'mike]

We have at least one pro that is schooled in the use of Schluters products---
Be patient--he'll check in soon.

I did read your post at Contractor talk---there you mentioned that the powdered thinset you used was 1 1/2 years old--If I am right---that might have been the problem.

Also--If I remember correctly, Ditra and Kerdi are only warrantied when UNMODIFIED thinset is used---
Let's see what Jaz has to say.

 

[ktl5005]

Not according to Schluter. Modified over plywood, OSB. That was told to me in a support call directly to Schluter. In addition, the place I bought the Ditra/thinset, a pro tiler shop, told me to use modified over plywood. And finally, here's a quote from the FAQ on Schluter's site:

"The type of thin-set mortar used to install DITRA depends on the substrate material. For example, to set DITRA over plywood or OSB, a modified thin-set mortar meeting the requirements of ANSI A118.11 is used. To set DITRA over concrete or gypsum, Schluter-Systems recommends an unmodified thin-set mortar meeting the requirements of ANSI A118.1. Please consult the Schluter-DITRA Installation Handbook before beginning your tile project to confirm the proper materials selection."

Also, directions state if apply directly to plywood subfloor, use modified thin set. IF setting over self leveled compound floor, use un-modified thinset.

 

[oh'mike]

Thanks, I set tile, but have never used the Schluter products---Someone will be along to help soon.

 

[kirm]

We have at least one pro that is schooled in the use of Schluters products---
Be patient--he'll check in soon.

I did read your post at Contractor talk---there you mentioned that the powdered thinset you used was 1 1/2 years old--If I am right---that might have been the problem.

Also--If I remember correctly, Ditra and Kerdi are only warrantied when UNMODIFIED thinset is used---
Let's see what Jaz has to say.

Hey Mike you nailed it. They tracked the code on the bag and they phoned today. They said the best before date as May 2013. That's bad... Here's the kicker: I looked for my receipt and, Saints be praised, I found it. I purchased the bag on May 13, 2013. Hmmm, who's fault is that? It seems I was set up to fail right after buying the bag. Of course waiting 2 years didn't help, eh?

Anyway, I bought a diamond wheel cup for a 4.5 inch grinder from KMS tools and started to take down the thinset. Folks, it was not pretty. I've got a layer of dust about a sixteenth thick on everything...even after wetting down the areas and closing doors and using a fan. It's ugly.

Avoid this if you can. Check your best before date before applying thinset. What a hassle, what a waste of XL, what a waste of time and money...I'm absolutely choked. And now I get to do it all over again.:vs_mad:

Thanks all for the help! BTW, Schluter confirmed it today; use modified between the XL and plywood. Oh and here's a pro-tip, use 1/4 by 1/4 trowel for XL. That came from an install video and the tech on the phone confirmed it.

 

[JazMan]

There is NO choice, you MUST use thinset that is appropriate for the substrate you're going over. This is always true regardless if you're installing Ditra or anything else. So, plywood floor, you MUST use modified thinset as the Schluter instructions tells us.

You may have done several things wrong. Using old thinset is not a good way to save money. You say it's about 18 months old. How do you know that? Is this when you bought it? If so, I doubt it was made that morning, so it might be much older.

Sounds like you didn't apply enough thinset, probably used the wrong trowel. Even if the thinset was bad, it should have made contact with close to 100% of the Ditra's fleece when the Ditra was "beat" to the floor to remove the air bubbles. You said you had 60% thinset transfer. That tells me you didn't apply enough thinset.

I see no reason to wet the plywood with a damp sponge. I might do that if I was going over concrete backer, but not plywood. Remember you're mixing the thinset a bit thinner than normal in the first place.

Jaz

*Best before May 2013 huh. How time flies. That means it might have been made in 2011 or no later than 2012.

 

[kirm]

Thanks Jazman, I actually pulled it up to see the 60% coverage BUT, I then added more thinset and pushed it down again. When pulled up again it had 100% coverage. It didn't matter because the crap was way too old. I used the trowel Schluter recommended (5/16" x 5/16" (8 mm x 8 mm) V-notched trowel). It was only today that I found out they recommend 1/4x1/4 for XL and that makes sense now. I'm going to phone the place that sold me the stuff in spite of it being stale dated to see if they will do anything. Not holding my breath there. I wasn't trying to save money I just didn't know the stuff had such a short life. To be honest that smacks of using garbage ingredients. Portland cement lasts forever as does sand. I can't see the plastic component having a short life either. My gut is telling me that they are cheaping out on the Portland cement and hoping other ingredients cover. I won't be using Mapei again. Laticrete is hard to find here but I know a place where I can get it.