# Ditra Issue



## MThompson (Mar 23, 2009)

Hello, yesterday I laid about 40 square feet of ditra in a small bathroom using Mapei's Ultraflex 2 and 1/4 notched trowel on top of a plywood sub floor. My husband and I pressed the ditra into the mortar really well and let it dry over night. The mortar has bonded really well with the plywood but I pulled on a corner of the ditra and I can pull it so that it separates from the mortar. Is this normal or should the fleece have bonded completely with the mortar and not allow the product to pull up?

One more question...I am planning on setting 13" tile using Keraset (I can't find Kerbond) using 1/4 square notched trowel. Is this acceptable? 

Thanks


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## LIHR (Jan 18, 2011)

How was the thin-set mixed? should be a fairly loose mix and you should pull a section up while installing just to check for complete coverage of the Ditra. Installed correctly you should not be able to pull it up as you are experiencing.


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## acglobal (Feb 7, 2011)

iam a flooring contractor by trade. i use ditra occasionally if circumstances require it. i used a v-notched trowel to laminate ditra to plywood (per manufacturer's instructions) using a latex modified mortar. i note that u said u used a 1/4 notched trowel. if your corners are coming up apply more thinset under those corners and check to make sure the fleecing is well bonded in all other areas. when installing the tile, use a unmodified mortar found at home depot or menards or lowes. This is required by manufacturer. unmodified mortar dries faster than a latex-modified one will.


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## JazMan (Feb 17, 2007)

Hi everyone,

Pulling a corner the next day applies a gozzilion times more stress that it ever receive in use. Don't do that if you did it right the first time. It will pull up if you grab a corner and peel it. After a few days the fleece will separate from the back though. It's normal and not a problem. 

You used a decent thin set to install Ditra to plywood. The trowel was wrong, it let too much mortar is all. I recommend (next time) either use a 5/16" V or the special Ditra trowel they now make. Too $$$ for most people. 

Now....You may have mixed it too thick and let it set too long so it skinned over. Only you can tell me that. Can you tell us if there's any transfer to the fleece? How did you push or ? Ditra into the mortar? How did you get the air out? 

The HD in my area does NOT carry an unmodified thin set worth taking home. Schluter tells us to use a premium mortar. The one you mentioned is not premium. 1/4x1/4 trowel fore 13" tiles is not right either. Who have you been talking with? I hope it wasn't same fuzzy cheeked person wearing an apron. :whistling2:

Jaz


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## acglobal (Feb 7, 2011)

i did not mention trowel size for installing 13x13 tile. but 1/4 x 3/8 is sufficient for 13x13. the unmodified mortar i use is TEC or MAPEI brand. The box stores around here carry them. DAP has a good one too


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## JazMan (Feb 17, 2007)

Tec and Mapei....all of the brands really, make good stuff. Some of their products just barely meet industry spec though. So, as long as the mortar meets ANSI A118.1, it's considered an unmodified thin set. However some of the cheap mortar are just too cheap to use in my opinion. 

Schluter wants you to use premium mortar when installing tiles on Ditra or Kerdi. You can buy cheaper grade of modified for under Ditra on ply if you wanna. ($14-16 a bag around here.) But unmodified is inexpensive already, so get something decent. ($12-14 +-). Keep the $6-9 stuff on the shelf to collect dust.

Yes, of course, a 1/4x3/8x1/4 should be the best trowel for most 13" tiles. 

Jaz


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## Bud Cline (Mar 12, 2006)

DITRA works as advertised. I don't know of anywhere in the instructions where it says to install the DITRA and the next day try to pull it out. You wouldn't paint your house then the next day scrape on the paint to see if it is stuck.

Install DITRA using the proper thinset mortar, the proper thinset mortar consistency, and THE PROPER SIZE TROWEL and it will be fine. Promise!


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## MThompson (Mar 23, 2009)

Thanks for the replies everyone. The thinset was mixed pretty thick and maybe should have been a little more loose but it wasn't skinned over and there was good contact with the fleece. The ditra was pressed into the thinset the flat side of a clean trowel in a similar manner to the Schluter video on the website. 

I think there is a good bond and I shouldn't be pulling on it. I'm one of those people that tends to want to make something last a lifetime and didn't expect that I could pull up a corner like I did 

I can't seem to find a premium thinset in Austin TX and have some experts at the local tile store (not HD or Lowes) telling me to use modified and let it dry for a few days before grouting. Apparently this is the method they use and they haven't had any problems. I'm pretty much conflicted at this point...


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## Bud Cline (Mar 12, 2006)

Use a premium modified thinset mortar to install the DITRA, then use unmodified thinset to install the tile. The modied should maybe cost about $28 per bag while the unmodified would be around $8-10 per bag.

Austin Texas WILL have a premium thinset readily available, go to Dal-Tile.


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