# Ditra Failure



## abacab

I recently had a flooring guy install my tile, and I had him use ditra (his first time). I used it before with no problems, and I don't think I would have had any here, but I couldn't supervise every second. From what I can tell he followed directions, and used unmodified mortar underneath. While I used modified, it was only after considerable research that I discovered this, and I don't blame him for using unmodified (it says it in huge writing on the label) I think if we had left it to dry, it would have been fine, but we were in a hurry, and it says you can go right over. As he was working, bubbles began appearing where he was working on the floor (presumedly from his knees applying pressure to the floor, and it working up) Now if it had been me, I would have stopped immediately and tore everything up, but he kept going, and I noticed it after about 1/3 of the tile was down. We had a deadline of a couple days for getting this job done for a showing, so I told him to continue (and crossed my fingers). I did have him tear up the areas that were not set and reapply modified mortar and put it back down.

My only gripe is with this stuff is that it is not idiot proof. There seems to be a thin line between getting it right and failure. Mix it too wet, and it weakens the mortar, mix it too dry and it doesn't stick. Even where it adhered good, the next day I could rip a section off with a slight flick of the wrist. I almost immediately had a cracked mortar line at the intersection of 4 tiles. I presume there was a bubble here, and the pressure of feet caused it to rock up and down. I ripped these 4 tiles up without much problem (like ripping up glued down carpet) It separated from both the floor and the ditra, but excellent adhesion of the mortar to the tile. For my floor I had 3/4 1x10 on a diagnal, and 1/2 exterior grade plywood screwed down every 4 square inches into the 1x10's beneath it only. 1x10's I screwed down.

Not sure what point I'm trying to make other than to be careful if you use this stuff. I probably won't be using it again. I don't believe there is enough initial tack to keep it down while working on it, even if I had used modified. It does not adhere like a tile does with mortar under it, it separates too easily.


----------



## angus242

abacab said:


> I recently had a flooring guy install my tile, and I had him use ditra (his first time). I used it before with no problems, and I don't think I would have had any here, but I couldn't supervise every second. From what I can tell he followed directions, and used unmodified mortar underneath. While I used modified, it was only after considerable research that I discovered this, and I don't blame him for using unmodified (it says it in huge writing on the label) I think if we had left it to dry, it would have been fine, but we were in a hurry, and it says you can go right over. As he was working, bubbles began appearing where he was working on the floor (presumedly from his knees applying pressure to the floor, and it working up) Now if it had been me, I would have stopped immediately and tore everything up, but he kept going, and I noticed it after about 1/3 of the tile was down. We had a deadline of a couple days for getting this job done for a showing, so I told him to continue (and crossed my fingers). I did have him tear up the areas that were not set and reapply modified mortar and put it back down.
> 
> My only gripe is with this stuff is that it is not idiot proof. There seems to be a thin line between getting it right and failure. Mix it too wet, and it weakens the mortar, mix it too dry and it doesn't stick. Even where it adhered good, the next day I could rip a section off with a slight flick of the wrist. I almost immediately had a cracked mortar line at the intersection of 4 tiles. I presume there was a bubble here, and the pressure of feet caused it to rock up and down. I ripped these 4 tiles up without much problem (like ripping up glued down carpet) It separated from both the floor and the ditra, but excellent adhesion of the mortar to the tile. For my floor I had 3/4 1x10 on a diagnal, and 1/2 exterior grade plywood screwed down every 4 square inches into the 1x10's beneath it only. 1x10's I screwed down.
> 
> Not sure what point I'm trying to make other than to be careful if you use this stuff. I probably won't be using it again. I don't believe there is enough initial tack to keep it down while working on it, even if I had used modified. It does not adhere like a tile does with mortar under it, it separates too easily.




So not a Ditra failure, but an installation mishap :thumbup:

Mixing thinset, regardless of what your using it for, needs to be correct.

You're kidding yourself if you think there's a _better _underlayment. You can quit on Ditra but instead, I'd learn how to properly mix the thinset.

All problems solved then! :thumbsup:


----------



## MAD Renovations

angus242 said:


> So not a Ditra failure, but an installation mishap :thumbup:
> 
> Mixing thinset, regardless of what your using it for, needs to be correct.
> 
> You're kidding yourself if you think there's a _better _underlayment. You can quit on Ditra but instead, I'd learn how to properly mix the thinset.
> 
> All problems solved then! :thumbsup:


 
Angus is bang on the money here.... You really can not blame the failure of the product if the installer does not know how to install it properly.


----------



## ApgarNJ

I was reading the package of ditra the other day. from my memory, and you guys tell me if i'm wrong here. for use over concrete floors, it says to put the ditra down with UNmodified thinset, then used unmodified to put the tile down as well. 
now for use of ditra over plywood subfloor, it says on the package to use MODIFIED thinset to put the ditra down to the plywood and unmodified to put the tile down. I think this is because the modified will help bond the ditra to the wood and is not necessary for use over plywood

now if you got to Schluter website, it say don't use modified and never states what I have read on the Ditra installation instruction right on the package.

i want to try this out but i'm worried about making a mistake the first time I use it. I have never had a tile crack or grout crack when using hardie backer with thinset underneath and screwed down. i know it may not be WATER proof but come on, who fills their bathroom with water. the little bit of water that splashes from a tub when taking a bath is not going to flood a room so bad that it leaks down through sealed grout through the tile backer, through the subfloor, and into the ceiling below to actually do any damage if it ever even reaches that point.

for a european shower with curbless designs, then I think schluter ditra and kerdi all the way. i'm just not sold that all tile floors have to have ditra on them. if the subfloor and joists are secure and strong. i see nothing wrong with hardiebacker. i don't use durrock. 

i just did my own bathroom floor tile yesterday and chose to use hardie. i though about ditra but for 15 bucks i got two sheets of hardie and for 90 bucks i would have had to buy a whole roll of ditra. i'm not out to say it's garbage. i think it does what it's supposed to do, i just don't think it's the only way to install tile.


----------



## ApgarNJ

"Using a thin-set mortar that is suitable for the substrate, apply the thin-set mortar (mixed to a fairly fluid consistency, but still able to hold a notch) using a 1/4" x 3/16" (6 mm x 5 mm) or 5/16" x 5/16" (8 mm x 8 mm) V-notched trowel."

this is off the schluter install sheet on their website. this is for putting the DITRA down to the substrate. so it's not specifically saying use unmodified for all applications, guys have to know what to use for what they are going over. 

then for installing the tiles to the ditra, it's always unmodified.


----------



## Anderson

You got it in one there ApgarNJ, the only time Schluter recommends modified is when laying ditra over a wood sub strata. Suprised Angus didn't pick up on that.


----------



## angus242

ApgarNJ said:


> I was reading the package of ditra the other day. from my memory, and you guys tell me if i'm wrong here. for use over concrete floors, it says to put the ditra down with UNmodified thinset, then used unmodified to put the tile down as well.
> now for use of ditra over plywood subfloor, it says on the package to use MODIFIED thinset to put the ditra down to the plywood and unmodified to put the tile down. I think this is because the modified will help bond the ditra to the wood and is not necessary for use over plywood
> 
> now if you got to Schluter website, it say don't use modified and never states what I have read on the Ditra installation instruction right on the package.
> 
> i want to try this out but i'm worried about making a mistake the first time I use it. I have never had a tile crack or grout crack when using hardie backer with thinset underneath and screwed down. i know it may not be WATER proof but come on, who fills their bathroom with water. the little bit of water that splashes from a tub when taking a bath is not going to flood a room so bad that it leaks down through sealed grout through the tile backer, through the subfloor, and into the ceiling below to actually do any damage if it ever even reaches that point.
> 
> for a european shower with curbless designs, then I think schluter ditra and kerdi all the way. i'm just not sold that all tile floors have to have ditra on them. if the subfloor and joists are secure and strong. i see nothing wrong with hardiebacker. i don't use durrock.
> 
> i just did my own bathroom floor tile yesterday and chose to use hardie. i though about ditra but for 15 bucks i got two sheets of hardie and for 90 bucks i would have had to buy a whole roll of ditra. i'm not out to say it's garbage. i think it does what it's supposed to do, i just don't think it's the only way to install tile.


Dan, you are correct:

Ditra over concrete: installed w/non-modified
Ditra over wood: installed w/modified
Tile over Ditra: non-modified always.

Personally, I just think it's confusing to someone who has never used it before because they're afraid to make any errors. In each roll of Ditra is an installation handbook. If you read and follow their instructions, you cannot screw it up....really. It is not hard.

I can see someone not wanting to use Ditra for a small project, especially if they don't tile often. I have over 450 sq ft of Ditra in stock. I get it substantially cheaper per sq ft by purchasing larger rolls and NOT buying it from HD. 

Are there other products used for underlayment? Yep.
Are there better products for underlayment? Nope.
Are there easier products to install? Nope.


----------



## PrecisionFloors

Modified over plywood/osb, Dryset over slab. Mix runny enough to embed the fleece with full coverage yet still hold a ridge. Pretty easy really. If you use too big of a notch, you will have the problems you saw with kneeling on it. Too small of a notch and you will not get enough coverage. Schluter sells trowels for Ditra and Kerdi installation, but they are not necessary....after your first 20sf you should be able to figure out the consistency and notch size, if you pay attention.


----------



## ApgarNJ

thanks, i'm glad i got it right. 
i have a few jobs coming up this summer and fall that are larger tile floors for kitchens. over plywood. so i'm going to use it then.


----------



## PrecisionFloors

Angus beat me to the punch...AGAIN :lol:


----------



## ApgarNJ

PrecisionFloors said:


> Modified over plywood/osb, Dryset over slab. Mix runny enough to embed the fleece with full coverage yet still hold a ridge. Pretty easy really. If you use too big of a notch, you will have the problems you saw with kneeling on it. Too small of a notch and you will not get enough coverage. Schluter sells trowels for Ditra and Kerdi installation, but they are not necessary....after your first 20sf you should be able to figure out the consistency and notch size, if you pay attention.


1/4x1/4 right?


----------



## PrecisionFloors

ApgarNJ said:


> 1/4x1/4 right?


Yep:thumbsup:


----------



## angus242

Anderson said:


> You got it in one there ApgarNJ, the only time Schluter recommends modified is when laying ditra over a wood sub strata. Suprised Angus didn't pick up on that.


The OP never said what the substrate was. Couldn't say what was supposed to be used in his situation.

Dan, I hate to disagree....but I disagree :laughing:

Here are two pics from the Ditra Handbook. Can't get a more simple instruction than a picture.


----------



## Anderson

I don't remember exactly but I think the XL was developed to do with the deflection in wood sub strata.


----------



## Anderson

You da man Angus 
but he did say
For my floor I had 3/4 1x10 on a diagnal, and 1/2 exterior grade plywood screwed down every 4 square inches into the 1x10's beneath it only. 1x10's I screwed down.


----------



## ApgarNJ

angus242 said:


> The OP never said what the substrate was. Couldn't say what was supposed to be used in his situation.
> 
> Dan, I hate to disagree....but I disagree :laughing:
> 
> Here are two pics from the Ditra Handbook. Can't get a more simple instruction than a picture.


Angus, I know it says that in the install handbook with DITRA, but if you go to their website, they have a THINSET FACTs page. and if you read that, you come away with the feeling that they don't want you using modified at all for ditra.

but yes, if guys read the instructions, it doesn't look to be that hard. i guess because it's new to me and I don't tile every single day, that it's intimidating.


----------



## ApgarNJ

Anderson said:


> I don't remember exactly but I think the XL was developed to do with the deflection in wood sub strata.


I think XL is for coming up to 3/4 hardwood flooring where maybe with thinner tiles you might be lower with normal ditra? 

angus will know.


----------



## angus242

Anderson said:


> I don't remember exactly but I think the XL was developed to do with the deflection in wood sub strata.


Ditra XL is actually designed to address the difference in adjoining floor heights. Seeing as regular Ditra is only 1/8" thick, sometimes you need a bit taller underlayment. However, technically, it does have better deflection properties which is shown with the minimum requires for installing Ditra XL over framing. But sorry, I am NOT installing tile over 24"OC with 3/4" ply :blink:

I use a 11/64" x 11/64" square trowel. I feel like going to 1/4" is just putting too much thinset down. Maybe I mix mine a bit thicker????


----------



## ApgarNJ

i have yet to see a residential job in my area with 24" oc joist spacing. 16 oc is everywhere. i stick build every addition we do, and it's always overbuilt. 3/4 over 24 oc, that's still asking for trouble on a tile floor.


----------



## angus242

ApgarNJ said:


> i have yet to see a residential job in my area with 24" oc joist spacing. 16 oc is everywhere. i stick build every addition we do, and it's always overbuilt. 3/4 over 24 oc, that's still asking for trouble on a tile floor.



You got that right! But I do see 19.2" OC using I-Joists.


----------



## Mike Finley

abacab said:


> My only gripe is with this stuff is that it is not idiot proof. There seems to be a thin line between getting it right and failure.


This is the nature with a lot of things in construction now a days. I talk about this very subject with all my guys all the time. Todays products are engineered within a narrow window or tolerance. With proper installations they do their job remarkably well but most highly engineered products today have a very low tolerance to any deviations. Guys who follow the "I've been doing it my way for 30 years!" are the ones who cause the most problems. Guys who think they know how to do something and refuse to take a few moments to read directions cause the most problems.

Construction science keeps moving forward producing these types of products and solutions, but they also create a greater chance of failure due to the small tolerances they have between right and wrong installations.

An easy example is something like trusses vs old school dimensional framing. Trusses solve a lot of problems, provide solutions and provide lower costs, but tolerances are much smaller between success and failure if you're not careful.

Ditra falls right into the same category as does so much of the products and materials we are using now.


----------



## PrecisionFloors

Mike Finley said:


> This is the nature with a lot of things in construction now a days. I talk about this very subject with all my guys all the time. Todays products are engineered within a narrow window or tolerance. With proper installations they do their job remarkably well but most highly engineered products today have a very low tolerance to any deviations. Guys who follow the "I've been doing it my way for 30 years!" are the ones who cause the most problems. Guys who think they know how to do something and refuse to take a few moments to read directions cause the most problems.
> 
> Construction science keeps moving forward producing these types of products and solutions, but they also create a greater chance of failure due to the small tolerances they have between right and wrong installations.
> 
> An easy example is something like trusses vs old school dimensional framing. Trusses solve a lot of problems, provide solutions and provide lower costs, but tolerances are much smaller between success and failure if you're not careful.
> 
> Ditra falls right into the same category as does so much of the products and materials we are using now.


Agreed :thumbsup:

What's worse are the guys that read the instructions (or are told the correct way) and still refuse to do it the prescribed way, with the "I've been doing it this way for 30 years" mentality. Like the manufacturer spend millions on R&D, testing, and literature writing just for the hell of it.


----------



## PrecisionFloors

angus242 said:


> I use a 11/64" x 11/64" square trowel. I feel like going to 1/4" is just putting too much thinset down. Maybe I mix mine a bit thicker????


The 1/4 x 1/4 I use is pretty worn down now that you mention it...Ditra is the only thing I use it for :laughing:

I use one these to embed it.

http://www.tools4flooring.com/crain-333-extension-wall-roller-p-774.html


----------



## Mike Finley

PrecisionFloors said:


> Agreed :thumbsup:
> 
> What's worse are the guys that read the instructions (or are told the correct way) and still refuse to do it the prescribed way, with the "I've been doing it this way for 30 years" mentality.* Like the manufacturer spend millions on R&D, testing, and literature writing just for the hell of it*.


 
Like Drywall guys putting dish washing liquid in drywall mud.:no: Cracks me up.


----------



## angus242

PrecisionFloors said:


> I use one these to embed it.
> 
> http://www.tools4flooring.com/crain-333-extension-wall-roller-p-774.html


Oh, you are fancier than me! :thumbup:

I use this:


----------



## Anderson

After I told my helper to read the back of a grout bag where it says wait 20 minutes before cleaning off, because he was trying to sponge it off right after I was putting it on. 
He replied "Instructions are for pilots"
Well I just had to laugh ;o)


----------



## angus242

Anderson said:


> He replied "Instructions are for pilots"


Or guys that want to keep their remodeling jobs :whistling


----------



## kevjob

PrecisionFloors said:


> I use one these to embed it.
> 
> http://www.tools4flooring.com/crain-333-extension-wall-roller-p-774.html


yup same here nothing better than feeling the ooze.


----------

