Tile not sticking [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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01-05-2003, 09:40 PM
I installed 12 x 12 tile on my bathroom floor over cement board. I used Acryl Pro Mastic glue. Out of about 60 tile I have 5 that will not stick. I have tried twice to install these but they just will not bond to the cement board. What should I do? All the other are just fine. I let them sit 48 hrs without walking on them. I also tiles aroune the tub with 4 X 4 tile and had no problems. What are my options? Thanks in advance for all your help.

the tiles were not cut so they were not wet when they were installed.

Also after pulling them up I have only about 40-60 % coverage on the backs of the tile.

If you have just a slight movement will the grout help hold these in place or will the grout crack? I am guessing that it will crack. Thanks

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01-05-2003, 10:10 PM
I think your first problem is using mastic on a floor ; the second problem is the coverage ; or lack thereof. You should be getting a minimum of 90% coverage.

Also, what did you use beneath the CBU and the subfloor? It should be modified or non-modified thinset depending on the type of CBU ; definitely not mastic.

In terms of options.... I would pull up all of the tiles ( with mastic), attempt to clean the tiles and CBU, then retile with thinset. If you did not use thinset beneath your CBU, it should come up to.

Don't worry about the mastic that has dried. Get it wet and it will re-emulsify and will come off quite easily.

Sorry for the bad news


01-05-2003, 10:11 PM
I'm not sure why those 5 tile don't want to stay down...but one thing is for sure...that mastic takes a long time to dry...especially under floor tile. It could be it wasn't dry, even after 48hrs, and then you walked on them and broke the bond. Nobody here recommends using mastic on floor tile..if you had used thin set, they would have set up overnight. Try putting them down again, and stay off even longer if you can. I'm sure you noticed that the mastic was still a little soft. even after 48 hrs..so the longer you wait the better for that stuff.:)

01-05-2003, 10:47 PM
Should I pull out the tile that have bonded to the cement board and that appear to be sticking fine? Or just the ones that are not bonding. Thanks in advance.

01-05-2003, 11:10 PM
Without seeing what you have there, that would be a hard question to answer. That mastic will stick pretty good when it has cured....but we'll need to know what trowel you used,and if possible..sending a picture would help. Is that possible?

01-06-2003, 09:03 AM
I used a 1/4 trowel. What would you like a picture of?

01-06-2003, 09:23 AM
A picture of the back of the tile and the floor where the tile is loose. Gives us an idea of what kind of contact you are getting on the tile and floor.

01-06-2003, 09:36 AM
In an effort to save some work I've made the same mistake once before. I used the same mastic for some floor tiles and a concrete slab and half of them setup in 24 hours and other half took almost a full week. I'll never do that again.

Good luck.