Setting Tile over Pre-filled Ditra

[nmarolf]

I pre-filled my Ditra Heat with a modified thinset and was planning to use the same modified thinset to set my porcelain tiles (6"x24", 1/8" spacing), knowing full well that I would have to wait before grouting (planned on a week or two).

Also knowing full well Schulter recommends unmodified, or use of their own like All-set.

My question is, I now find myself in a time crunch....and I found some Schluter All-Set locally (Customer service says it sets in 24 hours under porcelain). Is there any problem using the Schulter thinset over a different brand of thinset (Versabond)? The Versabond is full cured.
Both are modified thinsets so I think i'm ok doing so, but wanted to get some more experienced opinion(s). I called Schluter customer service about this question but the person I spoke with had nothing to say except they only recommend their own thinset - (of course!).

Thanks, I appreciate any thoughts. First time posting.

- Nathan

[cx]

Welcome, Nathan.

The All-Set will work fine over the Versabond. The Versabond will work equally well and at half the cost. I would use the Versabond. See my warranty information below.

My opinion; worth price charged.

[ss3964spd]

Welcome, Nathan,

I also installed Ditra Heat. I used Versabond to adhere it to the subfloor, to pre-fill it, and to set my 12X24 tiles. Almost 1.5 years later no issues whatsoever.

But to answer your specific question, no problem using All Set over top of the Versabond. I don't imagine, however, that the All Set will cure much faster than would Versabond.

[nmarolf]

Thanks for the replies.

My main concern was curing/drying time of the modified Versabond in this situation - I need to move the vanity into the bathroom about a 8-9 days from now and didn't know if that was enough time for the Versabond to cure and for me to grout. I'd rather use the Versabond since I have it on-hand.

- Nathan

[ss3964spd]

I still don't think All Set is going to cure appreciably faster than will Versabond.

But in any case both will have cured enough after 24 hours for light foot traffic. And your grout will need the same amount of time at least if it's cement based.

[nmarolf]

Thanks Dan,

I'll stick with the Versabond. I'll give it some time before I grout and go from there.

[jadnashua]

Some modified thin sets do not become stable until they also dry, but many modern ones do, so drying isn’t a big issue. It’s just that to the unwary, it’s hard to make a distinction of which ones will work, and which ones won’t. Cement cures at about the same rate whether it also dries or not it’s just that some modifiers aren’t stable (solidified) until they first dry out. A modifier that isn’t stable can allow movement, and that can compromise the bond. There are speed set, modified thin sets that are stable in hours...most compatible, normal ones can take a day for light loads or so, and more to reach full strength (industry standard is 28-days).

[Kman]

The fact that you pre-filled will speed up the dry time vs. filling and setting up the same day.

But you'll need to key the wet mortar into the dried layer of mortar on the mat, just as if it were concrete, to get the maximum bond.