# Subfloor/Tile help.



## Tank (Jan 29, 2011)

Good day everybody.

Well, I find myself in the situation of doing a floor for someone, well, rather, half of the floor. I know absolutely nothing about floors, I focus on fencing, shelters and outdoor structures. 

The skinny of it is a friend of mine ripped up there old flooring, which needless to say was glued down like a bugger. Then, they DID NOT lay down Ditra or anything of the sort, they put down tile, straight to the sub-floor plywood. The grouting in between the tiles has cracked after only one month of the floor being in there. Now, the gaps between the tiles are big, about 1/4'' inch, and they used a non sanded grout. I thought non sanded grout was for 1/8'' inch spacings?

I smashed out all the old tile today and am back to the sub-floor. I was going to beef it up with a second layer of plywood, but I discovered someone else had already done this, and there is in fact over 1 inch of plywood on the floor, and it is pretty darn solid. My concern is the floor is obviously covered in the old mortar, and the old glue from the floor before. It's fairly smooth, but do I need to worry about sanding this down before laying my Ditra?

It is a very small bathroom. The new tiles going in are 13x13, and porcelain material. In all, it will only take about 15 tiles to do the entire floor, as I said, a very small bathroom. 

Given this tile size and material type, what is the best trowel to use when laying down the thinset for the Ditra? I am only laying the Ditra, another friend they know is laying the tiles. 

Looking for any information that will help me along with this. As I said, I have never done this kind of thing before, and I want to be sure I have the Ditra installed correctly. Tearing up 2 layers of sub-flooring isn't an option, especially when the plywood is in great shape. 

Thank you!


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## angus242 (Oct 20, 2007)

You do want to grind off as much of the old thinset as possible. If you don't, you might leave small ridges that will not allow the Ditra fleece to fully adhere to the plywood.

Clean the floor very well after grinding. Wash it down with a damp rag/sponge just before installing Ditra.

Spread the *modified* thinset over the floor before troweling the ridges out. Don't skimp on the thinset. Use a quality modified mortar. 

Use around a 5/16" v notched trowel. I have a 11/64" square notch that I use but they're hard to find.


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## Tank (Jan 29, 2011)

What do you suppose the best way is to clean up the sub-floor? There isn't very much wood visible, it looks more white from all the old thinset on it. 

Any suggestions on name brand of thinset? I have never mixed thinset before so I don't have a clue what's what with this stuff.

Thank you for the reply!


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## TheItalian204 (Jun 1, 2011)

Tank said:


> What do you suppose the best way is to clean up the sub-floor? There isn't very much wood visible, it looks more white from all the old thinset on it.
> 
> 
> 
> !


I think Angus meant grinding off just ridges and not whole floor.

Take a vacuum to the floor right after (One in HD,Ridgid one is for sale right now for 65$)

You can try easy acid(weaker version of muratic) dissolving it 15 to 1.

Maybe even vinegar 10 to 1 with water.

I would suggest trying to take palm sander with really coarse sanding paper to the floor,that might help especially if its cheap(ER) thinset.

For this kind of project I would advice you buy regular pre-mix stuff that has adhesive added to it(already)


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## angus242 (Oct 20, 2007)

You can start with a scraper. Grinder will probably work. Belt sander too. Specialty tools help but you might not have access to them. I use one of these. Eats up the old thinset like nothing:


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## angus242 (Oct 20, 2007)

Do not use any acids of any kind. They can be absorbed in the ply and affect the adhesion with the new thinset.

I did mean grind off all the old thinset.


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## TheItalian204 (Jun 1, 2011)

angus242 said:


> Do not use any acids of any kind. They can be absorbed in the ply and affect the adhesion with the new thinset.
> 
> I did mean grind off all the old thinset.


Did you mention to him you signing him up for about 2 hours of hell without that BOSS tool of yours?


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## angus242 (Oct 20, 2007)

Tank said:


> Any suggestions on name brand of thinset? I have never mixed thinset before so I don't have a clue what's what with this stuff.


I'm a Mapei guy. I think Lowes carries that brand. I'd use Ultraflex 2.

Depends on what's available to you. Most brands will have a good, better best. Go with at least the better.

And lordly, nothing premixed :no:


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## angus242 (Oct 20, 2007)

TheItalian204 said:


> Did you mention to him you signing him up for about 2 hours of hell without that BOSS tool of yours?


Belt sander will be very messy but quick. 

I can't help the old installation went bad and now the labor to fix it will suck.


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## Tank (Jan 29, 2011)

All good information thank you.

The floor is pretty smooth considering. There is only a few places where it is just small chunks of thinset left about the size of a quarter. 

Closest thing to me for supplies is a Home Depot. They tell me they bought thinset, but I think they purchased unmodified, as they told me the packaging on the Ditra specifically calls for a unmodified thinset.

Also, someone said use a premix, they also claim it says very specifically to never use a premix with Ditra.

I thought everyone knew you never lay tile down without a product like Ditra or at least SOMETHING over the sub-floor. Oh well, I can't fault them for trying, the tile job looked great until you seen the cracks up close!

What about grout? What should be used once the tiles are in place? I don't want that grout to crack on them again. Sanded maybe?


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## angus242 (Oct 20, 2007)

Non-modified thinset goes over the Ditra when installing the tile.

Grout; anything 1/8" or larger gets sanded. You should seal the grout after installation (and proper curing).


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## Tank (Jan 29, 2011)

Ok, just checked there website, and if I got it right, it says to use a modified thinset for adhering the Ditra to the plywood sub-floor. 

Modified does not require any latex additives to make the porcelain stick, correct? 

Ah, that explains why the grout was cracking. No Ditra and they used non sanded grout for 1/4'' inch spacings.

This sounds pretty simple, hopefully not my famous last words. Good thing my first floor is a very small area!


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## JohnFRWhipple (Oct 20, 2009)

Tank said:


> Ok, just checked there website, and if I got it right, it says to use a modified thinset for adhering the Ditra to the plywood sub-floor.
> 
> Modified does not require any latex additives to make the porcelain stick, correct?
> 
> ...


Tank if your subfloor is flexing Ditra is not going to help you.

You mentioned Glue in an earlier post. Was it ready made thin set that was used to set the first tiles? That could be the problem there.

Can you see the framing from below? I would suggest you look for compromised joist.

Good Luck.


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## SSC (Feb 8, 2011)

JohnFRWhipple said:


> Tank if your subfloor is flexing Ditra is not going to help you.
> 
> You mentioned Glue in an earlier post. Was it ready made thin set that was used to set the first tiles? That could be the problem there.
> 
> ...


I'm with John on this. If there is over an inch of subfloor and it was fastened correctly and it was in good condition as you say with thinset it should of held. If they used mastic then thats where the movement is coming from. Check the structure maybe 24" O.C. spacing and too long of a span.

Instead of grinding i would prefer to pull the top layer of ply and replace it with some heavy duty 3/4" then ditra or the like


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## CO762 (Feb 22, 2010)

Tank,
What does the transition look like from the bathroom to the ajoining room/hallway?


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## Tank (Jan 29, 2011)

Transition isn't to bad. There is linoleum (if I remember correctly) in the hall way. It will need a trim piece for sure to make it look nice.

The glue on the floor was from the linoleum that was pulled up some months ago in the bathroom. After they pulled that up, they cleaned it as best they could, and then laid down ceramic tiles, right onto the plywood. 

The tiles themselves did not crack. There was merely a few hairline cracks in the grout work. The spaces between the tiles are quiet large, and they used non sanded grout, which would explain the grout cracking, not? They admitted to me yesterday that they did not follow the instructions on the box for the grouting, and simply went with what they thought was better. 

I am going back today to do some further investigating into the structure. It is a one level home so there is a crawl space, but from what they have told me, it is a nasty one. 

I will try and take some photos and post them here.


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## Tank (Jan 29, 2011)

Here are the photo's. Don't mind the tiles laid out by the door, the owners were just seeing how it would match up.


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## Tech Dawg (Dec 13, 2010)

It looks like the tiles were just backbuttered and stuck to ply... it was probably a bond breaker and not a structure issue + it doesn't help if the old vinyl glue wasn't cleaned up properly.
Belt sand that mother down and set the Ditra :clap:


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## aptpupil (Jun 12, 2010)

that's not how the tiles are going to be laid out, right?
other than that, looks like you're on the right track.


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## Tank (Jan 29, 2011)

aptpupil said:


> that's not how the tiles are going to be laid out, right?
> other than that, looks like you're on the right track.


That's how they say they want to lay them, in that pattern. What's the best way?

Also as I asked before, what is the best trowel for this size and type of tile?


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## Tech Dawg (Dec 13, 2010)

Use a minimum of 1/4"x3/8" notch or 1/2x1/2.

Its a small room and strange layout so you may want to do a diamond or brick lay pattern...


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## CO762 (Feb 22, 2010)

The paint job looks great and nice corners on the drywall. Get a good transition and have at it.


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## Tank (Jan 29, 2011)

They have purchased Versabond modified thinset, and unmodified for the project.

Is this modified thinset ok for using to lay the ditra to the plywood? Do I need to only add water, or do I need to purchase the latex additive as well?

http://www.homedepot.com/buy/floori...tified-thin-set-mortar-white-50-lb-50340.html


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## Tech Dawg (Dec 13, 2010)

I wouldn't use that to set it to ply, but that's me...


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## Anderson (Sep 7, 2009)

The versa bond from depot is about the same price as I pay for Laticrete


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## Tank (Jan 29, 2011)

Tech Dawg said:


> I wouldn't use that to set it to ply, but that's me...


Well, if I shouldn't be using that, could you please tell me what to look for?

I need this in laymens terms here guys. I need to know exactly what to buy, what it is called, how to mix it, I need all that information. I know nothing about flooring, not a single thing, I am in the dark on this one.

My only resource is Home Depot, I have nowhere else to get the supplies from.


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## Tech Dawg (Dec 13, 2010)

I'm not totally edjucated on the CBP line but id look into using the Flexbond to set the Ditra to ply and the Versabond should be ok to set the tile with


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## CO762 (Feb 22, 2010)

Tank said:


> Is this modified thinset ok for using to lay the ditra to the plywood? Do I need to only add water, or do I need to purchase the latex additive as well?


Holy Crap Tank, don't take this wrong, but you know nothing about which you are doing....or are going to do. 

This is just me....I'll help out other people in the trades sometimes, but they gotta not start at absolute zero (kelvin for those eggheads out there). They gotta put forth some effort on their own. Grrrrr........

You have the home depot mini roll of ditra there. There's directions in it.
Or here:

http://www.schluter.com/media/DitraHandbook.pdf


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## Tank (Jan 29, 2011)

I did admit, I don't have the slightest clue when it comes to flooring. It is something I have never done before or bothered to research.


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## angus242 (Oct 20, 2007)

I do agree with CO. There's a video or two on how to install Ditra on their site. It would be in your best interest to watch them. They will give you the exact methods, steps, products, etc. It's good and well that you're seeking help online but as you can see, there is mixed advice.

Follow _their_ instructions and you can't got wrong.


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## Tank (Jan 29, 2011)

Got it, thanks guys!


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## CO762 (Feb 22, 2010)

Tank said:


> I did admit, I don't have the slightest clue when it comes to flooring. It is something I have never done before or bothered to research.


I believe you're just getting into the trades--no biggie as unless someone's dad owned a trade business, we all had to go out and learn it from somewhere/someone. The trade I was taught for work was old school tile and stone. I started out there as a bucket cleaner/carrier, trash collector, broom pusher, worked my way up to a grouter (finisher) etc. and had to earn my way to a trowel--took about two years.

When I branched out into other trades, I had some training in some but a very long time ago, so before going there as "entry level", I studied everything I could, yakked with people working in that trade on whatever job I was on, studied some more, watched, and went back and asked more questions, etc. So by the time of day one in different trade X, I already was informed about the materials, the tools, the methods, etc. I respected the trade and the tradesman enough to do that. I put in the time and effort even before I went there for the chance.

Someone that showed up to do work and has "not bothered to do the research" on what they don't know, then started asking me homeowner DIY grade questions....well, I'd just turn and walk away. 
Something to think about. YMMV.


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## Tank (Jan 29, 2011)

CO762 said:


> I believe you're just getting into the trades--no biggie as unless someone's dad owned a trade business, we all had to go out and learn it from somewhere/someone. The trade I was taught for work was old school tile and stone. I started out there as a bucket cleaner/carrier, trash collector, broom pusher, worked my way up to a grouter (finisher) etc. and had to earn my way to a trowel--took about two years.
> 
> When I branched out into other trades, I had some training in some but a very long time ago, so before going there as "entry level", I studied everything I could, yakked with people working in that trade on whatever job I was on, studied some more, watched, and went back and asked more questions, etc. So by the time of day one in different trade X, I already was informed about the materials, the tools, the methods, etc. I respected the trade and the tradesman enough to do that. I put in the time and effort even before I went there for the chance.
> 
> ...



You seem to be misunderstanding.

These are just friends of mine who asked me to do this for them, knowing that I don't know how to do it, but that I can probably figure it out. This is not a professional job for someone I don't know who is paying me for my time and efforts.

I have no use for knowledge of tiling, I am not a tiling guy. I build pole barns, fences, and horse shelters, I don't do anything else but those things. I am not trying to learn anything about the trade of setting tiles, I just wanted to find out enough to get this small job done. I don't need to prove anything to anybody, nor do I owe anyone the kiss my shoes respect attitude that seems to be coming up.


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## TheItalian204 (Jun 1, 2011)

Tank said:


> someone I don't know who is paying me for my time and efforts.
> 
> I have no use for knowledge of tiling, I am not a tiling guy. I build pole barns, fences, and horse shelters, I don't do anything else but those things. I am not trying to learn anything about the trade of setting tiles, I just wanted to find out enough to get this small job done. I don't need to prove anything to anybody, nor do I owe anyone the kiss my shoes respect attitude that seems to be coming up.


My friend,you are misunderstanding what people are telling you.

Noone is telling you to kiss their shoes. However,internet is powerful tool where you can just type in "Ditra" and watch countless number of videos and entries on how to install it and what exactly to do.

I also have terrible amount of questions about tiling since I am just a mason.

However I spend every night researching project if I get one to make sure I do not **** up.

Slapping tile on is the easiest,its not ****ing other steps up that is hard.

People are aggrivated for simple fact that you should not being doin it even if those people are your friends. If you **** something up,do you think your friends are not going to hold you accountable for it?

If there is going to be tiler coming in,wth are you doing Ditra for.

As far as you not having interest in tiling trade,I would suggest you still learn how to install it unless you planning to build barns and horse shelters for rest of your life.

Dont take offence please,just trying to help out.


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## CO762 (Feb 22, 2010)

Tank said:


> ...knowing that I don't know how to do it, but that I can probably figure it out.
> ...
> I have no use for knowledge of tiling


I guess I've wasted my time and yours then.
FWIW, I think that's one of the reasons why a lot of people don't answer questions about their trade.


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