Thinset dry time [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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04-08-2011, 11:22 AM
We just laid 12x12 travertine over existing ceramic tile in a small bathroom and have a houseful of people coming over in two days...
We used Custom Building Products PremiumPlus® Standard Thin-Set Mortar - which has a recommended dry time of 24 hours minimum before grouting. Does the thinset need longer to cure because it's over ceramic tile? Thanks!

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04-08-2011, 11:28 AM
After 12-24 hours you should be okay for light traffic and grouting; but that grout will also need to set 12-24 hours; and preferably should be sealed before you start having major foot traffic/parties; you can probably _just_ eek by getting it grouted, but your thinset wont have full strength and you're potentially risking your installation IMO.

generally speaking haste makes waste, I wouldn't rush it and I'd keep people off the floor if at all possible.

04-08-2011, 12:07 PM
Welcome Heather, :)

So, you laid new travertine over existing ceramic tile with Premium Plus mortar? If so, cure time is the least of your worries I'm very sorry to say. :nod:

Verify that you did use Premium Plus and if so, I'd probably start taking up those tiles sooner rather than later. For new tile to bond to existing tile, a modified mortar is needed. With Premium Plus, it's just a matter of time, probably not long, till the new ones start to come loose, grout starts cracking, etc... sorry.

...there may be one saving grace. Did you mix with water or admix?

from the PP specs:
Mix with Thin-Set Mortar Admix — ANSI A118.4
and A118.11 Specifications:
Interior and exterior floors, walls, countertops
Areas subject to freeze-thaw cycles
Exterior grade plywood (interior residential and light
commercial dry areas)
Existing ceramic tile

04-08-2011, 12:31 PM
Welcome, Heather. :)

While most folks would recommend a modified thinset mortar for your application, as Dana is hinting I believe, a whole lotta stone was set successfully for a whole lotta years before the advent of modified thinset mortar. Before the advent of any thinset mortar, matter of fact.

If your previous tile surface was properly prepared, and if mortar was properly keyed into both surfaces, your new tiles should be adequately bonded.

Now, that's not to say there might not be some structural issues at play, here, but that mortar shouldn't be a big problem. :)


Ah, now I see Dana has added some clarification to his post and his concern was as I expected. While Premium Plus may not have been my first choice of dry-set mortar, I'm still thinking it'll do OK if it was properly installed.

Do tell us how the old surface was prepared and how the mortar was applied.

And the 24 hours should be an adequate wait before grouting.

My opinion; worth price charged.

04-08-2011, 05:16 PM
FWIW, thinset doesn't really dry, it cures...this is a chemical reaction, and will occur without exposure to ANY air at all. Now, a modified thinset needs to do both dry and cure. You can't really speed up the chemical reaction much (it is a little faster in hotter temps, but not all that much).