Virgin Thin Set User

Old 10-15-05, 12:30 PM
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Virgin Thin Set User

Classic case of father-in-law showing me the ropes, but not telling me you can't push a rope... I laid ceramic tile in my bathroom on a wood subfloor with backer board and Master Blend standard thin set. Floor spans are small but there seems to be some movement or the wrong thin set application. I know now we did a few things wrong, one of which is that that backer board was butted up tight...Get to the chase...My grout cracked after a few months and I noticed a loose tile. To my surprise I was able to pry up a full 12x12 with my fingers, no adhearance of the thin set to the tile at all! Sadly I continued to be able to do this tile over tile. Couple of questions:

1. How do I get the old thin set off the backer board without destroying the backer board?

2. Should I have added a flex additive to the thin set?

My ingnorance abbounds on this subject, I'd really appreciate any assistance. I've read quite a few of the responses on other issues and have learned a lot already.

Waiting with bated breath...
Old 10-15-05, 04:10 PM
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You used a good thinset.

Were the CBU panels set in thinset before fastened to the floor?

Size, span and spacing of floor joists?
Old 10-16-05, 03:23 PM
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WHat size trowel did you use? I would think that with larger tile, you may need to use the 1/2 inch notches to lay the thinset, so that there is good surface to thinset adhesion.

Blessings - and Don't give up!
Old 10-16-05, 05:29 PM
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Masterblend is cheap unmodified thinset, what type of tile was it, ceramic, stone, porcelain?, what subfloor is under the CBU, what size trowel did you use?.

No easy way to get up the thinset, grind it, chip it, whatever.

Masterblend can work without an additive over concrete, I always use modified thinset, it could have skimmed over while setting and also sounds like bad coverage as well.
Old 10-16-05, 07:47 PM
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Sleepless in Ceramic...

Thanks Tileman, Debbie and Daniel.

It was ceramic tile put down with a 1/4" trowel. I did NOT use thin set under the CBU under the direction of others? The floor joists are stout 2x10s on 16" centers and I believe the deck is 3/4" plywood.

Looks to be good coverage on the thinset and the tiles were completely coated, but when they came up, there was only minor dusting of thin set left on the tiles.

It looks like I put bloody Pam on the backs of the tiles before I put them down! I'm considering using the back side of the forsaken tiles as cookie sheets and frying pans due to their ability to repel anything they touch!

I did notice a crack in the thin set under a few of the removed tiles, but I would have expected the tiles to stress, not just break completely free of the thinset.

Coming to grips with doing the job again is painful enough, I just don't want to make the same mistake twice...Thanks in advance for any more insights...

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