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Mortar and grout issues - Bathroom Floor

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Posted by: from Victoria
11/12/2022 at 7:17:19 AM

We used a bit of self levelling compound for the bathroom floor and waited the specified amount of time before applying 8x8 porcelain tiles and we used 1/4 " spacers. We used premium pre-mixed mortar but found we had to build up in some areas as we didn't realize the floor was as unlevel as it turned out to be in a few spots.

The mortar didn't seem to dry for a long time especially where we built up with mortar, and we had to wait about a week for the mortar to dry (at least the tiles weren't moving and seemed dry, and then applied Mapei flex color grout and let the groat set for about 24 hours.

Several days later 2 tiles have popped up and a little of the groat is cracking. We've pulled up the 2 tiles, they were really wet underneath. I can't figure out why. They'll have to be installed.

I've had a heater going in the cool bathroom trying to dry where the tiles were taken out up after removing all the mortar wondering if it's just that the floor underneath is cold.

I see the groat is cracking in a few small spots around a couple of tiles. I thought best to wait for everything to get good and dry with a heater going in the bathroom, and then will reset using dry mortar rather than the premix stuff hoping it will dry better for the two tiles. Am I on the right track?

And should I saw out the groat where it's cracked around a few tiles and redo it? It's only been about 4 days since I did the original groating. Obviously we've gone off the rails somewheres, and I'm wondering if using premix mortar over the floor that had self levelling compound on it was the issue or if it's something to do with having a cold floor? What do we do now?

Any thoughts or ideas as to what we can do to salvage the situation would be welcome. Thanks kindly

REPLIES (2)
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Date/Time11/13/2022 at 12:47:46 PM

Hi Paula, sorry to hear that

You should had apply self levelling, Schluter Ditra with modify thinset if OSB subflooring

and for tile over ditra, unmodifiy thin set, no Modify, since the Latex-modified mortars must dry for the polymers to coalesce and form a hard film in order to gain strength. When sandwiched between two

impervious materials such as DITRA and ceramic tile, including porcelain tile, drying takes place very slowly through the open joints in the tile

covering. [According to the TCNA Handbook for Ceramic, Glass, and Stone Tile Installation, this drying period can fluctuate from 14 days to

over 60 days, depending on the geographic location, the climatic conditions, etc.].

Hopr thi help

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Date/Time11/13/2022 at 4:33:22 PM

This is a common problem if not prepped correctly. The 1st problem is using "pre-mixed mortar" that stuff is garbage, you should have used the stuff the pros use " dry hand mixed thinset for the application". Cracking should never happen if substrate done right. Floor must have a underlayment layer 1st at least 3/8'-1/2" plywood on top of the "sub-floor". If you went over vinyl or existing flooring, you did it wrong, rip out all old flooring to the sub-floor, anything else is amateur time. Floor should have been dry, level etc. and then the mortar & tile applied...wait 24 hrs. to dry then grout, wait 24 hrs. and buff, ready to use after this...the whole job should have taken 2 days max!, use a fan if very high humidity in the air but same thing 2 days. It was likely done incorrect as per stages...only solution now is tear it all out and re-do. Recommend to hire a pro this time if this was a DIY.

PS: My company is based out of Duncan and never had a issue doing tile floors professionally on the island. Prep is "everything" on any remodel project.

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