Ditra tile floor installation, newbiem questions about thinset [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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03-06-2007, 01:47 PM
Hi all!

My name is John. I'm already midstream into a bathroom floor and tub surround tiling project. Thus far, I've already cut the Ditra to the right sizes for the floor. I've also hung Hardi-backer on a 20" vertical tub surround (half wall).

I actually mixed my first batch of PC thinset (Versabond Foritified) and secured about 30% of my Ditra to the plywood floor. I used regular ole' water to mix the PC thinset. I hope I wasn't supposed to add a latex additive. So that's my first question: should I have? The portions I have put down seem nice and snug to the floor.

Second question: I got a surprise call today. My tile showed up much earlier than I expected. So I ran to the Depot to purchase the unmodified thinset. The only one they stock there is "CustomBlend" unmodified. So I bought that. So really my second question is two-tiered: Is this a good unmodified to use for securing the tile to the Ditra? And given the plasticky nature of the Ditra, should I use plain water again for the tiling part? Or should I drop the $20 on the additives (Admix)?

I will post up some pictures asap of my ongoing project. I'll probably be posting up a lot soon :)

Thanks in advance for any advice -

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Brian in San Diego
03-06-2007, 01:58 PM

Versabond is an acceptable thinset for securing ditra to plywood subfloors. The polymers are already in the powder, no admix is necessary. I wouldn't recommend the CustomBlend for your installation. I think you'd want to go with PremiumPlus and at the very least MasterBlend. You don't want to use those "economical" mortars because they're...well...cheap. You do want to use an unmodified or dryset mortar and there are many choices, but I think you should take the CustomBlend back and getting a thinset of higher quality. No additives to whatever thinset you use. Unmodified thinset dries by a chemical reaction. Modified needs air to dry. Between the ditra ans the tile not much air is getting in, hence the unmodified thinset.


03-06-2007, 02:03 PM
I used the same versabond fortified thinset to put down my ditra in my bathroom... I believe that it is a modified thinset already so no need for the additives....

I also used the customblend unmodified and it worked great for my ceramic tile.... I know you dont want to use the additives on top of the ditra per their website. Use only the unmodified with water....

If your tile is porcelain though I read somewhere on this board that there were some sort of problems with the tile sticking down to the ditra ?????

We'll have to have help from one of the professionals on that one i guess......

Good luck,


03-06-2007, 02:06 PM
Welcome, John. :)

What Brian said.

My opinion; worth price charged.

03-06-2007, 02:08 PM
Thank you Brian. Edit: Thank you ALL! You're quite fast at the replies. ;)

I'll take a look at Lowes to see if they stock any other varieties of the unmodified thinset. I'm glad I asked!

I might as well take the time to ask another question.

I cut a circle in the Ditra to go around the classic "blue" toilet flange. When I tore up the linoleum sheet, the linoleum was UNDER the flange. I unscrewed the flange from the floor to raise it up a hair and ripped out the linoleum pieces. I then used new zinc coated screws to resecure the blue metal flange to the plywood floor. And like I said, I used a piece of Ditra with a hole cut just to size to surround that flange. Is this the proper way? I'll obviously be tiling around the flange. The flange may end up being around a quarter inch below the tile surface and I have a spacer to add if the distance is an issue (although I doubt it.)

The flange is secured properly, right? Or is it supposed to sit on top of the installed tile??
Thanks again!

Brian in San Diego
03-06-2007, 02:46 PM

The flange is properly installed. After you add ditra/thinset/tile you may need at least a 1/4" spacer.


03-06-2007, 03:14 PM
If it's possible to raise the flange/drain, the correct place for the flange is on top of the finished floor, in your case the tile.

My opinion; worth price charged.

03-06-2007, 10:15 PM
I'll take a look at Lowes to see if they stock any other varieties of the unmodified thinset. John - Lowes carries a couple different brands. If yours has Mapei like mine pick up the Kerbond. :tup2:

03-07-2007, 07:55 AM
If it's possible to raise the flange/drain, the correct place for the flange is on top of the finished floor, in your case the tile.

I would guess this is to better protect the wood subfloor, i.e. from leaks or wax. However since my Ditra is already cut to surround the secured flange, I guess I would have to rip up the Ditra and cut a new piece with a smaller hole to fit under the flange. Hmmm...

Questions about screwing the flange to the tile...special drill bit? Anchor?

If I don't do this, is it junky? I don't like doing junkie install stuff. I'm willing to redo it if it's important.

03-07-2007, 08:14 AM
The flange should be at the finish floor for height, not on top. Add spacers under the flange and rescrew. No need to get ditra or tile under the flange.

03-07-2007, 08:27 AM
Is there such thing as a two-piece spacer? I have on hand a one piece but it's size is such that it would have to go over the existing flange. I can't really put anything under the existing flange unless it's two halves of a flange.

Interesting anyway. 2 people suggest tiling around the flange, 1 for tiling under the flange.

03-07-2007, 08:29 AM
The flange will work as you suggest, Scott, but best operating practice and the plumbing codes still call for installation of the flange on top of the finished floor. :)

My opinion; worth price charged.

Racer X
03-07-2007, 10:26 AM
If your tile is porcelain though I read somewhere on this board that there were some sort of problems with the tile sticking down to the ditra ?????

Is that right?

03-07-2007, 12:48 PM
I ran a test that I posted on another thread using Ditra, porcelain (16 x 16) and unmodified thinset. After 2 days of curing the thinset was stuck well to the Ditra but did not adhere well to the porcelain tile. I followed the advice of CX :bow: and some other folks here and ran another test. I buttered the back of the tile and let it cure longer. Much better results. The buttering and the longer cure did the trick.

Butter the back of the porcelain tile.
Use a good quality thinset mixed properly.
Let it cure.
Have a party on your new floor. :lol1:

Racer X
03-07-2007, 01:19 PM
Whew!.... I was almost ready to take my porcelain tile back. Thanks

03-07-2007, 01:20 PM
Hi Todd.

It might be a good idea for you to go back into your other thread http://johnbridge.com/vbulletin/showthread.php?t=45660&page=4&pp=15 and post the results of that second test. This is the second time today I've seen posts from members worried about using unmodified thin sets under porcelain after reading about your first test.


03-07-2007, 02:09 PM
An install over sheetroock on accounta this is a test floor. Do not try this at home. :shades:

Ditra, Laticrete 317 un-modified thinset mixed with water, porcelain tile. Removal after seven days curing.

03-07-2007, 04:18 PM
I've updated my other thread.

I did not mean to scare anyone away from Ditra and porcelain.


It works just fine. Follow the guidance of the folks here on this site. They won't let you do it wrong. :clap1:

Racer X
03-07-2007, 05:13 PM
Hey Todd,

Is that the whole link to your Ditra and porcelain thread? My confuser says "The page cannot be found". :think:

Thanks for the update.

Racer X
03-07-2007, 05:19 PM
searched around and found it... thanks again