Tiling over cutback help [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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04-27-2008, 03:10 PM
I am currently tiling over old cutback with 18x18 ceramic tiles. I was advised to use Versabond, but it did not adhere to the cutback. Then, I was advised to use UltraFlex 2......"guaranteed to bond to the cutback"......with no success. My tiles, especially in high traffic areas are hollow and pop up with minimal effort. I was advised to prep my cutback floor two different ways:
1. scrape as much off as possible, mop with TSP and rinse
2. do not scrape, mop with TSP and rinse
I tried both methods in different areas of my floor, but got the same result as stated above.

Had two professional installers come out and received two different problem solving methods:
Installer 1. Using the same UltraFlex 2, do a skim coat over the cutback. Then proceed laying tile as normal.
Installer 2. Skim coat the entire surface with an elastomeric ISO product. This product will bond to the cutback and the thin set will bond to it.

The only product I have found that I thought might work is Redguard. Will the RedGuard adhere to the cutback? Has anyone used this product to skim coat over cutback?

Also, I have noticed that when I pop up a tile, they tile pops off the mortar with minimal effort. Seems like there should be a better bond there. Any advice on that front? How strong is a normal mortar to tile bond?

Thanks so much for your help!!!

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04-27-2008, 04:01 PM
Somethings not right. Those products should be working, Boogs.

I'm curious, how long are you waiting to check for a bond? More than just a day or two I hope. With a slab pretty well sealed up with cutback adhesive along with 18" tiles, maybe porcelain even, any modified mortar you use is going to take some time to dry out and develop a good bond.


04-27-2008, 04:41 PM
The hollowing of the tiles has been progressive....over several weeks/months.

Is there something I could be doing wrong with the mortar? It seems fairly straight forward......

04-27-2008, 05:25 PM
Yes, it should have worked. Sometimes, I'll mix up a slurry of Versabond....REAL LOOSE and flat trowel it onto the floor. Let it dry and it gives the final morter something to "bite" to. The Redgard should probably work, as well....

04-27-2008, 05:59 PM
Can you explain to me how the slurry.....same as a skim coat?....would adhere better to the cutback than the regular bed of mortar?

Also, when I have popped up loose tile....the mortar seems easily broken apart and is easily separated from the tile. The tile is coming up off the mortar bed in a solid piece. Is this normal?

John Bridge
04-27-2008, 06:13 PM
Hi Boogs, :) is that a nick name?

It is highly unusual for any mortar to separate from the back of the tile. Separating from the floor substrate is usually the case. So what you're saying is the thin set is bonding to the cutback but not to the backs of the tiles? I think you'll need to describe what the backs of the tiles consist of. They are porcelain tiles, I suppose, but do the backs contain quite a bit of a white substance? Is there a glare to the clay on the backs? Again, this is really strange. :)

04-27-2008, 06:30 PM
Use TEC SuperFlex when you reinstall. Works great on cutback.

John Bridge
04-27-2008, 06:45 PM
Ken, have you read this? I think it's sticking to the cutback but not the tile. Ever heard of that?

04-27-2008, 07:27 PM
I use mapei Ultracontact with success over cutback, esp. with large format because you can mix it up to be a medium bed material. It sticks like crazy and it's harder than hell.

04-27-2008, 07:30 PM
Sorry John, I actually completely miss read the entire thing it turns out :)

Either way TEC SuperFlex is a great product over cut back.

04-28-2008, 08:35 AM
The mortar is not sticking to the cutback. The mortar is sticking to the tile, but when I pop up a tile....the separation between the tile and mortar takes minimal effort. I was concerned that I am not getting a proper/normal bond between the mortar and tile. I was asking how strong that bond should be....

The tiles are ceramic, red clay color on the back with a small circular pattern. There is some white but no glare. I have been wiping the backs of each tile with a very slightly damp sponge before setting. I was told this would remove any dust particles and help it adhere.

What type of product is the TEC Superflex? Where do I get it?