Large format tile using Ditra

[Haruki]

First time posting to this forum. I have perused several threads, but didn't find exactly what I was looking for. That said, I saw really helpful answers, so thought I would give this a try.

Here are my questions:

1. I am laying Ditra over 3/4 T&G plywood with exterior grade glue over 100 year old 2 x 10 joists 16" O.C. I plan to use modified thinset for this application (something like Laticrete 253 Gold, or Mapei UltraFlex2, whichever I can find in these strange times). The tile I am laying is 15" x 30" porcelain, and as I understand the Schluter install manual calls for unmodifed thinset. Problem I have is I have read that unmodified isn't great for porcelain, and I am having trouble following the specifications of thinset (using water meets ANSI X or using admixture meets ANSI Y, etc). So the question: I am looking for a recommendation of a thinset for this application of porcelain LHT over Ditra.

2. for one shower wall, my wife chose some 3 x 12 opaque glass tile. I planned on placing it on Kerdi board as I had done on a past project with ceramic tile, but I now see that can be an issue. The tile is recommended for showers. As with question 1, what thinset might work well for this opaque glass tile over Kerdi?

3. When laying the glass tile on drywall in a dry area of the bathroom, can I simply use Type 1 Mapei tile adhesive, or is there a trick to this as well?

Thank you for the advice, and apologies if this is covered elsewhere within the forum.

[smifwal]

I am not familiar with laticrete's 253 but Mapie's ultra flex 2 is not sufficient for the 15x30 that you reference. You shouldn't set glass with mastic,it will never dry. I am a fan of Ardex products, do you have access to them?

Maple lft would be good for you 15x30 and any glass tile mortar is what you should be using for your glass

Ardex X5 would cover all your needs

[CaliGrown]

Shawn 253 = A creamier Versabond.
From Laticrete: 253 will work, an LFT formulated mortar may be what you want depending on the properties you’re expecting from the mud. Tri-Lite is a good mud for large stuff, also LHT/LHT plus and 4XLT are good ones too. 257 is and 255 are out of this world products.

From Mapei: Ultrafloor Plus is good stuff, one of my new found lovers!

[John Bridge]

Welcome aboard, Brian.

If you are worried about product warranties, use Schluter thin set for everything. On the other hand, I used Custom's VersaBond thin set over Schluter products for years without problems. For large format tiles you could use VersaBond LFT. Both products cure well over Ditra and Kerdi.

For the glass tile, check with the supplier as to which installation products to use.

[Haruki]

Shawn & Christopher:

thank you both for your rapid responses. Rereading, I see that I have could have been more clear regarding my questions, to clarify:

1. Thinset #1 for use between plywood and Ditra (unless people talk me into a different membrane) was to be Laticrete 253 or some other similar product.

2. Thinset #2 for use between Ditra and 15" x 30" porcelain tile


3. Thinset #3 for glass tile 3" x 12" in shower wall on Kerdi board.

4. Thinset #4 for same glass tile on drywall in dry area.


If I follow both of you, I takeaway:

• Polymer modified thinset is okay over Ditra despite Schluter's installation instructions for Ditra.
  
• Candidates for thinset #2 include: Mapei LFT, Mapei Ultraflex Plus; Ardex X5, Laticrete Tri-Lite; LHT/LHT Plus; 4XLT; 255; 257
  
• Candidates for thinset #3 & #4 include: "any glass tile mortar," and Ardex X5.
  
• Ardex X5 would work for all four applications.

Having looked at the specs for Laticrete and Ardex, I see now there are tons of options. So I am going to ask a follow up and hope I don't get too many slings and arrows or radio silence:

Since polymer modified thinsets above Ditra are okay, is there a polymer modified thinset that would work well for Thinset #1 and #2. From Shawn, I gather Ardex X5 could be one example.

A bit more detail: most of the 15" x 30" is going on the floor, but some will be laid on plaster in a dry area of the bathroom behind a freestanding tub. I had planned to rough up the plaster with a wirebrush and paint it with Mapei AquaGuard, then thinset tile to the wall (which is very flat suprisingly). Given this application, it would appear that something like Tri-Lite is optimal for the walls...but perhaps there is one that I could use for both.

I don't mind using a few different products...just want laying this large tile on the wall to be as easy as possible.

Thank you in advance!

[HS345]

Hi Brian, there are a couple of caveats for using modified mortars over Ditra and Kerdi. Number one, it would void any Schluter warranty (which most of us don't consider a problem). Number two, only certain modified mortars work well over Ditra and Kerdi. Ardex X-5 would satisfy all your needs, and, as the whirl famous John Bridge hisownself said, Versabond LFT would also work. In my professional opinion, Ardex X-5 is much easier to use for wall applications than Versabond LFT.

In regards to your question about Type 1 Mapei tile adhesive, that is a mastic, and should never be used for glass tile. The Ardex X-5 would work very well for your glass tile.

[jadnashua]

There are at least four different classes of modifiers used in thinsets...you want one that becomes stable even without drying. One that does not work prior to drying (curing is the same on all) use a synthetic latex.

Schluter does make and sell a modified thinset they will guarantee works, if you choose.

The cement grows crystals during the curing process. They can be fragile if the modifier that's coating them isn't stable and the tile moves for whatever reason (thermal, pressure, shear, etc.), messing with the bond. As long as the modifier stabilizes along with the curing, they'll work without drying.

[Haruki]

Wow again; thank you all.

I was typing up my second clarifying post while the team here was simultaneously providing more great information...the "whirl famous" John Bridge answers as well as Greg and Jim. I go out to shovel some snow here in Denver and come back to all this.

I am going to:

1. buy one of these books as a sign of my appreciation;
2. post more questions as I go; and
3. try to be a better human.

appreciate the warm welcome.

Kind regards,

[MAPEI - Technical Service]

Hey there Brian,

If you want one mortar to use on the whole project, we would recommend Ultraflex 3. If you can't find it locally, Ultraflex LFT would be a great choice for your large format tile, and Adesilex P10 (Mosaic and Glass Tile Mortar) mixed with Keraply would be the mortar of choice for your glass pieces.

[jeffnc]

Only some polymer modified thinsets are allowed over Ditra. For example, Schluter can control the formulation of their own Schluter All Set. If not using that, then use an unmodified. When they talk about modified thinsets being recommended for certain porcelain tiles, they're talking about substrates other than Ditra/Kerdi.

In practice, pretty much anything is going to work fine. But we're talking about Schluter warrantying it or recommending it, and I always follow manufacturers instructions.

If your glass tile is truly opaque, then you don't have to worry about the color behind (unless it shows through the sides of the tiles.)

[Haruki]

Happy holidays gang,

Getting closer to the job now, but first a few inspections from Denver.

My question now is: best method for ripping 15x30 tiles, and a desire to limit the purchase of expensive new tools (to an extent anyway). (And yes, I should just use a smaller tile, but that issue is behind us.)

I used a static table wet saw on 12 x 24 and the tension around the blade had me flipping them around, but it worked okay. For this 30”, short of buying a massive tile cutter, would folks use a grinder freehand with a scrap straightedge, or something like the dewalt handheld set saw?

Thanks again for all the advice.

[cx]

The only real problem I know of with the little hand-held wet saws in that application is that most do not have a base plate that allows convenient use with a straight-edge. But, if your cut edges will be hidden, you can free-hand a sufficiently straight cut with one of those saws. I have not used the DeWalt, but have a similar Felker FHS-4.

Cutting outside (they're a bit messy) in Denver this time of year might be an even greater impediment.

My opinion; worth price charged.

[jeffnc]

You could rent a larger tile saw, use a dry blade on a circular saw (ultra dusty), use an angle grinder for occasional cuts that will be hidden (equally dusty), or possibly use a tile cutter (snapper) instead.